Spiral steel pipe manufacturing, chemical industry, construction and oil and gas electricity required for important national key project materials, especially oil thermal power construction and other industries as supporting GB spiral pipe market direct power. GB is a measure of a country can become an important symbol of steel power, is a country's comprehensive competitiveness reflected. Spiral steel pipe as one of important new material, has been listed as a national focus on the development of strategic new industries. Spiral steel pipe industry as a traditional branch, early development of spiral steel pipe is mainly to meet the required heat and oil industry, the core material, and highly professional, but the quantity demand is small, difficult to scale production resulting in low business efficiency features. However, with the upgrading of industrial structure, the downstream equipment manufacturing base material requirements for increasingly high value-added products are also increasing, spiral pipe has a broad space for development.
At present China's steel industry competitiveness compared with the international advanced level, there are still some gaps. Main features: First, the low proportion of high-end products can not meet the development needs of the national economy is still dependent on imports; Second, GB spiral steel pipe spiral steel industry and the majority of companies do not establish their own technology innovation system and mechanism, the lack of independent intellectual property rights with technology and product development capabilities. High-end equipment manufacturing, new energy, such as city gas heat pipe with spiral steel industry will be closely related to the future of the highlights spiral pipe market demand, China's equipment manufacturing industry, mainly in the core technology and components controlled by others, the development of spiral steel pipe The key is to occupy the high-end market.
The present situation, the urgent need to break the bottleneck: a, to improve product quality, promote energy conservation, pollution reduction; Second, to improve China's steel industry concentration, eliminate backward production capacity, accelerate the spiral steel pipe industry pace of technological innovation; Third, to accelerate industrial chain construction to form a complete industrial chain of steel. Aviation, and other advanced high-speed rail transportation equipment, blower equipment, metallurgical equipment, electronic equipment and so will be the highlight of the spiral steel pipe market demand, with government support efforts to increase and deepening of reform, China's steel industry will usher in spiral development.
Friday, June 28, 2013
Longitudinal piling pipe fracture encountered in production
When the temperature drops below a certain temperature value, the data will be found to brittle state, the impact absorbed energy decreased, a phenomenon known as cold brittleness, high strength metallic materials low stress brittle fracture occurs in the process, far from homogeneous isotropic organize data organization have cracks, there will be inclusions, porosity and other defects, which are a material can be seen in the micro-cracks. Therefore, the design also based on the work piling pipe straight seam to select suitably cold temperature brittle transition temperature data.
Generally data are assumed to be homogeneous isotropic continuous analysis that this approach is based on the design of safe, and sometimes accidental breakage incidents. As hot-rolled tube defects such as cracks or high-precision cold drawn tube is made after the tank, cold drawn seamless when. Breakage occurs during use, almost no plastic deformation occurs, in general are brittle fracture.
Brittle fracture caused by a variety of reasons, such as: precipitates on the grain boundaries, regardless of the intensity ratio of the matrix strength strong or weak, are all causes cracks; grain boundary segregation of inclusions also cause fracture; addition, even in far less than the yield limit alternating loads can also cause fatigue fracture phenomena.
Generally data are assumed to be homogeneous isotropic continuous analysis that this approach is based on the design of safe, and sometimes accidental breakage incidents. As hot-rolled tube defects such as cracks or high-precision cold drawn tube is made after the tank, cold drawn seamless when. Breakage occurs during use, almost no plastic deformation occurs, in general are brittle fracture.
Brittle fracture caused by a variety of reasons, such as: precipitates on the grain boundaries, regardless of the intensity ratio of the matrix strength strong or weak, are all causes cracks; grain boundary segregation of inclusions also cause fracture; addition, even in far less than the yield limit alternating loads can also cause fatigue fracture phenomena.
How to control the location of the high-frequency induction coil
Excitation frequency straight seam piling pipe in the excitation circuit capacitance, inductance is inversely proportional to the square root, or the voltage and current proportional to the square, as long as the change in the circuit capacitance, inductance, or voltage and current can change the size of the excitation frequency, so as to achieve control of welding temperature. For low carbon steel, welding temperature control in the 1250 ~ 1460 ℃, can meet the pipe wall thickness 3 ~ 5 mm penetration requirements. In addition, the soldering temperature can be achieved by adjusting the welding speed.
The two edges of tube is heated to welding temperature, oil casing in the extrusion roller extrusion, to form a common metal grain mutual penetration, crystallization, and ultimately form a solid weld. If the extrusion pressure is too small, the number of crystals formed on the small joint, weld metal strength was declining, the force will crack.
Weld by welding and extrusion welding scars will produce, need to be cleared. The removal method is on the rack cutter, pipe fast motion by the burr gelling. Pipe inside burr is generally not cleared. However, if the extrusion pressure is too large, will make the molten weld metal is extruded, not only reduces the weld strength, and will generate a lot of internal and external burrs, and even cause defects such as weld seam ride. When the heat input is low, the heated soldering temperatures reach the edge of the weld metal structure remains solid, forming incomplete fusion or penetration. Soldering temperature is mainly affected by the impact of high-frequency eddy current heating power, according to the relevant formulas can be learned, high-frequency eddy current frequency heating power is mainly affected by the impact of thermal power and eddy current excitation frequency is proportional to the square; while current excitation frequency and by the excitation voltage, current, and capacitance, inductance.
The two edges of tube is heated to welding temperature, oil casing in the extrusion roller extrusion, to form a common metal grain mutual penetration, crystallization, and ultimately form a solid weld. If the extrusion pressure is too small, the number of crystals formed on the small joint, weld metal strength was declining, the force will crack.
Weld by welding and extrusion welding scars will produce, need to be cleared. The removal method is on the rack cutter, pipe fast motion by the burr gelling. Pipe inside burr is generally not cleared. However, if the extrusion pressure is too large, will make the molten weld metal is extruded, not only reduces the weld strength, and will generate a lot of internal and external burrs, and even cause defects such as weld seam ride. When the heat input is low, the heated soldering temperatures reach the edge of the weld metal structure remains solid, forming incomplete fusion or penetration. Soldering temperature is mainly affected by the impact of high-frequency eddy current heating power, according to the relevant formulas can be learned, high-frequency eddy current frequency heating power is mainly affected by the impact of thermal power and eddy current excitation frequency is proportional to the square; while current excitation frequency and by the excitation voltage, current, and capacitance, inductance.
The high frequency welding for straight seam welded steel pipe
High-frequency welding is based on the principle of electromagnetic induction and the exchange of electric charge in a conductor skin effect, eddy current heating effect and proximity effect, so that the weld edges of the steel locally heated to a molten state, the roller of the extrusion, the crystals butt welds achieved indirectly together, so as to achieve the purpose of the welding seam high frequency induction welding is a welding (or pressure contact welding), it does not need weld filler, no welding spatter, weld heat affected zone narrow, beautiful welding molding, welding good mechanical properties etc., so in the production of steel has been widely applied.
It is the use of high-frequency welding pipe alternating the skin effect and proximity effect, steel by roll forming, the formation of a circular cross-section tube disconnected, near the induction coil inside the tube near the center of rotation of a or a group of impedance device (magnet), the impedance tube opening is formed with an electromagnetic induction loops in the skin effect and proximity effect under the action of the opening edge of the tube produces a powerful and concentrated thermal effects, the weld edge rapidly heated to the desired temperature by the pressure roller welding extrusion, the molten metal to achieve indirect co-crystal after cooling to form a strong butt weld.
It is the use of high-frequency welding pipe alternating the skin effect and proximity effect, steel by roll forming, the formation of a circular cross-section tube disconnected, near the induction coil inside the tube near the center of rotation of a or a group of impedance device (magnet), the impedance tube opening is formed with an electromagnetic induction loops in the skin effect and proximity effect under the action of the opening edge of the tube produces a powerful and concentrated thermal effects, the weld edge rapidly heated to the desired temperature by the pressure roller welding extrusion, the molten metal to achieve indirect co-crystal after cooling to form a strong butt weld.
Layered thick wall seamless steel tube defect analysis
Thick-walled seamless steel pipe mainly used for high-strength structural steel. From the hierarchical defect mechanism, the general that the non-metallic inclusions in the tube will destroy the continuity and compactness of steel, severe mixed internally or stratification of the pipe. Another thought is hydrogen induced cracking, ie from accumulation of hydrogen in the steel caused by high gas pressure inside the metal, the inner tube is formed in the white circle point in the expansion of cracking during rolling, forming layered defects. In addition, two roll rotary piercing inhomogeneous deformation plasticity resulting stress exceeds the strength can also cause delamination.
In the smelting strictly controlled circumstances, many third situation occurs, the control measures:
1, to improve toughness plastic tube
Improve steel cleanliness and reduce harmful inclusions; increase the proportion of equiaxed crystal slab to reduce center segregation and center porosity; using reasonable cooling system to avoid internal cracks occur within the slab; right off the assembly line rolling slab or billet take slow cooling process, reducing the internal stress, in order to ensure billets and finished pipe and mechanical properties to meet the technical standards.
2, the reasonable control of the heating temperature
By measuring the thermoplastic curve, choose the best heating temperature. Also note that there is sufficient heating tube holding time, to reduce the plastic deformation resistance and improved toughness.
3, lower roll speed
Speed roll piercing process is a key parameter, roll speed the process of change from low to high, there is a critical stratification began to roll speed. Roll speed is low, the tube is easy to form cavity; roll speed is high, and capillary tube is easy to form a layered defects. To and capillary tube to eliminate layered defects should roll speed is reduced to the critical stratification began to appear less roll speed.
In the smelting strictly controlled circumstances, many third situation occurs, the control measures:
1, to improve toughness plastic tube
Improve steel cleanliness and reduce harmful inclusions; increase the proportion of equiaxed crystal slab to reduce center segregation and center porosity; using reasonable cooling system to avoid internal cracks occur within the slab; right off the assembly line rolling slab or billet take slow cooling process, reducing the internal stress, in order to ensure billets and finished pipe and mechanical properties to meet the technical standards.
2, the reasonable control of the heating temperature
By measuring the thermoplastic curve, choose the best heating temperature. Also note that there is sufficient heating tube holding time, to reduce the plastic deformation resistance and improved toughness.
3, lower roll speed
Speed roll piercing process is a key parameter, roll speed the process of change from low to high, there is a critical stratification began to roll speed. Roll speed is low, the tube is easy to form cavity; roll speed is high, and capillary tube is easy to form a layered defects. To and capillary tube to eliminate layered defects should roll speed is reduced to the critical stratification began to appear less roll speed.
Thick-walled piling pipe custody and maintenance
Thick-walled piling pipe custody and maintenance of the quality of key thick steel wall thickness uniformity to the number of thick-walled steel pipe wall thickness is not controlled will directly affect the quality and usefulness of steel pipe, thick wall steel pipe, large diameter seamless steel pipe generally used in a variety of machining, thick-walled parts processing, uniform wall thick-walled steel pipe will directly affect the quality of post-processed parts, thick-walled steel pipe wall is not controlled, the overall quality of steel is not strictly . Appropriate choice of venue and warehouse storage space or warehouse thick steel, should be selected in clean, smooth drainage area, away from harmful gases or dust factories. Presence on the ground to clear the weeds and all debris, keep the thick-walled steel pipe clean. Not in a warehouse with acid, alkali, salt, cement and other thick-walled steel pipe with corrosive materials stacked together. Different varieties of thick-walled steel pipe should be stacked separately, to prevent confusion, to prevent contact corrosion. Large steel, rails, shame steel, large diameter seamless steel pipe, forgings, etc., may open air.
Small steel, wire rod, rebar, the diameter thick wall steel pipe, steel wire and wire rope, etc., can be expected in a well-ventilated storage shed, but must be on the thatch underlay. Some small thick-walled steel pipe, sheet, strip, silicon, or thin-walled small-diameter thick-walled steel pipe, a variety of cold-rolled, cold drawn thick wall steel pipe, and the price is high, corrosive metal products, can be stored in storage. Treasury should be selected according to geographical conditions, the general ordinary enclosed warehouse, ie roof with walls, doors and windows tightly with ventilation warehouse. Treasury requires attention to ventilation sunny, rainy close attention to moisture, and keep a suitable storage environment. Reasonable stacking, stacking principle advanced first put palletizing firm requirement is to ensure safe conditions, so that according to species, size stacking, different kinds of materials to be, respectively, palletizing, prevent confusion and mutual corrosion, prohibit pile position near the store have a corrosive effect on the thick-walled steel items principles open dumps steel, the following must be of stone or wood pad, stack face tilted slightly to facilitate drainage, and pay attention to materials placed flat against bending caused deformation stacking height, manual operation does not exceed 1.2m, mechanical operation does not exceed 1.5m, stack width not exceeding 2.5m. stacks and stacks should be left between a certain channel, check the road is generally O. 5m, entrances and exits, as the size of the material and transport machinery, generally 1.5 to 2. Om. Pile padded bottom, if the concrete floor warehouse of Chaoyang, booster O. 1m to; For mud, shall elevate O. 2 ~ 0.5m. For open space, concrete floor padded O · 3 ~ O · 5m, mud face booster 0.5 ~ O. 7m. Angles and channels open dumps should stoop to put that mouth down, I-beam should stand up, thick-walled steel pipe I can not groove face up, in order to avoid stagnant water rust.
Small steel, wire rod, rebar, the diameter thick wall steel pipe, steel wire and wire rope, etc., can be expected in a well-ventilated storage shed, but must be on the thatch underlay. Some small thick-walled steel pipe, sheet, strip, silicon, or thin-walled small-diameter thick-walled steel pipe, a variety of cold-rolled, cold drawn thick wall steel pipe, and the price is high, corrosive metal products, can be stored in storage. Treasury should be selected according to geographical conditions, the general ordinary enclosed warehouse, ie roof with walls, doors and windows tightly with ventilation warehouse. Treasury requires attention to ventilation sunny, rainy close attention to moisture, and keep a suitable storage environment. Reasonable stacking, stacking principle advanced first put palletizing firm requirement is to ensure safe conditions, so that according to species, size stacking, different kinds of materials to be, respectively, palletizing, prevent confusion and mutual corrosion, prohibit pile position near the store have a corrosive effect on the thick-walled steel items principles open dumps steel, the following must be of stone or wood pad, stack face tilted slightly to facilitate drainage, and pay attention to materials placed flat against bending caused deformation stacking height, manual operation does not exceed 1.2m, mechanical operation does not exceed 1.5m, stack width not exceeding 2.5m. stacks and stacks should be left between a certain channel, check the road is generally O. 5m, entrances and exits, as the size of the material and transport machinery, generally 1.5 to 2. Om. Pile padded bottom, if the concrete floor warehouse of Chaoyang, booster O. 1m to; For mud, shall elevate O. 2 ~ 0.5m. For open space, concrete floor padded O · 3 ~ O · 5m, mud face booster 0.5 ~ O. 7m. Angles and channels open dumps should stoop to put that mouth down, I-beam should stand up, thick-walled steel pipe I can not groove face up, in order to avoid stagnant water rust.
Advantages of hot-rolled large diameter seamless steel pipe
Large diameter seamless hot-rolled advantages: destroy the ingot casting organizations, grain refinement of steel and eliminate defects in the microstructure, so that the dense tissue steel, mechanical properties are improved. This improvement is mainly reflected in the rolling direction, so that the steel is no longer certain extent isotropic; pouring bubbles formed cracks and porosity, but also in under the action of high temperature and pressure welding.
Large diameter seamless steel pipe magnetic particle testing or penetrant testing can effectively find surface cracks, folds, double skin, hairline, pinholes and other surface defects. For ferromagnetic materials, magnetic particle inspection method should be preferred, because of its high detection sensitivity; For non-ferromagnetic material, such as stainless steel seamless pipe, then a penetration assay.
Reserved resection margin when both ends is small, causes the detection apparatus, both ends of the head may not be effectively detected, and ends there is most likely the site of cracks or other defects. If large-diameter seamless steel pipe ends there is a potential tendency to crack, the installation of the weld heat affected also possible to make the potential crack. Therefore, it should be noted that certain areas of the welded steel tube detection, to detect defects in steel tip extensions. Use the online austenitic seamless insulation is damaged or when rain may have infiltrated the site, should pay attention to the infiltration testing to find stress corrosion cracking or pitting corrosion and other defects.
Large diameter seamless steel pipe magnetic particle testing or penetrant testing can effectively find surface cracks, folds, double skin, hairline, pinholes and other surface defects. For ferromagnetic materials, magnetic particle inspection method should be preferred, because of its high detection sensitivity; For non-ferromagnetic material, such as stainless steel seamless pipe, then a penetration assay.
Reserved resection margin when both ends is small, causes the detection apparatus, both ends of the head may not be effectively detected, and ends there is most likely the site of cracks or other defects. If large-diameter seamless steel pipe ends there is a potential tendency to crack, the installation of the weld heat affected also possible to make the potential crack. Therefore, it should be noted that certain areas of the welded steel tube detection, to detect defects in steel tip extensions. Use the online austenitic seamless insulation is damaged or when rain may have infiltrated the site, should pay attention to the infiltration testing to find stress corrosion cracking or pitting corrosion and other defects.
Forming large size seamless pipe fittings
Large size seamless pipe fittings forming technology are: hot spinning method, hot extrusion, hot piercing rolling method, thermal expansion push the system path method. As follows:
1, hot spinning method
It is the flat blank or pre-formed blank is fixed to the rotating mandrel, spin the wheel blanks pressure while rotating wheel for axial feed, through one or more processing, to obtain a variety of thin-walled hollow rotary system the process of goods. Its advantages are high precision, good mechanical properties, wide range of sizes. Tools mold is simple, easy to replace, lower production costs than other methods. The main disadvantage is the production of long working hours, low output, the processing of the tube by the device length limit, the size is short.
2, the hot extrusion method
Required before extrusion billets were machined pretreatment, when squeezing the tube diameter less than 100mm, the equipment investment is small, less material waste, technology is more mature. But once the tube diameter size increases, the use of hot extrusion method requires large tonnage and high-power devices, the corresponding control system should be upgraded.
3, hot piercing rolling method
Hot piercing rolling the longitudinal extension and cross rolling mill extension based. Rolling and rolling extending mainly limited MPM rolling, less rack MPM tube rolling, three-roll MPM tube floating mandrel mill rolling and rolling. These methods produce high efficiency, low metal consumption, good product quality, advanced control system is widely used. Oblique Rolling rolling method with less investment, short process, suitable for low-volume, multi-species, multi-standard and high-precision production of seamless pipes and the same has been widely used.
4, the thermal expansion push the system path method
Push the system expanding device is simple, low cost, easy maintenance, economical and durable, flexible product specifications transform, if necessary, prepare a large-diameter elbow and other similar products, you only need to add some accessories to. Suitable for the production of thin-walled seamless tube diameter Heavy timber, it can not exceed the production capacity of the thick-walled steel pipe equipment.
1, hot spinning method
It is the flat blank or pre-formed blank is fixed to the rotating mandrel, spin the wheel blanks pressure while rotating wheel for axial feed, through one or more processing, to obtain a variety of thin-walled hollow rotary system the process of goods. Its advantages are high precision, good mechanical properties, wide range of sizes. Tools mold is simple, easy to replace, lower production costs than other methods. The main disadvantage is the production of long working hours, low output, the processing of the tube by the device length limit, the size is short.
2, the hot extrusion method
Required before extrusion billets were machined pretreatment, when squeezing the tube diameter less than 100mm, the equipment investment is small, less material waste, technology is more mature. But once the tube diameter size increases, the use of hot extrusion method requires large tonnage and high-power devices, the corresponding control system should be upgraded.
3, hot piercing rolling method
Hot piercing rolling the longitudinal extension and cross rolling mill extension based. Rolling and rolling extending mainly limited MPM rolling, less rack MPM tube rolling, three-roll MPM tube floating mandrel mill rolling and rolling. These methods produce high efficiency, low metal consumption, good product quality, advanced control system is widely used. Oblique Rolling rolling method with less investment, short process, suitable for low-volume, multi-species, multi-standard and high-precision production of seamless pipes and the same has been widely used.
4, the thermal expansion push the system path method
Push the system expanding device is simple, low cost, easy maintenance, economical and durable, flexible product specifications transform, if necessary, prepare a large-diameter elbow and other similar products, you only need to add some accessories to. Suitable for the production of thin-walled seamless tube diameter Heavy timber, it can not exceed the production capacity of the thick-walled steel pipe equipment.
Wednesday, June 26, 2013
Rectangular Pipe energy use in new areas
Rectangular Pipe in construction, machinery manufacturing, steel construction projects, shipbuilding, solar bracket, steel structure engineering, electrical engineering, power plants, agricultural and chemical machinery, glass curtain wall, car chassis, airports, construction piling pipe etc. are widely used.
Rectangular pipe ground source heat pump technology is the use of previously groundwater, groundwater through technology and equipment for the heat. Even rich reserves of shallow groundwater, groundwater eventually collected on the geological conditions more stringent requirements, long acquisition is likely to cause a certain area groundwater scarcity, in order to maintain constant levels of nature, with the acquisition of deep groundwater recharge techniques needed this is a must.
Rectangular Pipe heat pump technology is widely used in industrial fields, can be collected and industrial emissions, waste water, waste heat for reuse. On the one hand, heat can be reused, saving coal resources; the other hand, can greatly reduce the temperature of the exhaust gas wastewater discharges into the natural environment caused by thermal pollution, can be said to serve multiple purposes. To promote environmental protection in the modern new low-carbon energy society, reducing the energy consumption of the construction sector, but also must pay sufficient attention to.
Rectangular pipe ground source heat pump technology is the use of previously groundwater, groundwater through technology and equipment for the heat. Even rich reserves of shallow groundwater, groundwater eventually collected on the geological conditions more stringent requirements, long acquisition is likely to cause a certain area groundwater scarcity, in order to maintain constant levels of nature, with the acquisition of deep groundwater recharge techniques needed this is a must.
Rectangular Pipe heat pump technology is widely used in industrial fields, can be collected and industrial emissions, waste water, waste heat for reuse. On the one hand, heat can be reused, saving coal resources; the other hand, can greatly reduce the temperature of the exhaust gas wastewater discharges into the natural environment caused by thermal pollution, can be said to serve multiple purposes. To promote environmental protection in the modern new low-carbon energy society, reducing the energy consumption of the construction sector, but also must pay sufficient attention to.
Cleaning and use of spiral piling pipe
There is a good variety of cleaning spiral style, you can use a wire brush, which is rough sandpaper these tools to conduct an overview of the disposal of the steel, so that it can spiral before doing heavy cleaning cleaning if you can remove loose and flips oxide, rust and welding slag and other dirty tools. If you think this style fighting strength of trouble, you can choose to use two kinds of chemical and electrolytic pickling another way to deal with these two conventions are often used in the mouth, and also rough. Spiral pipeline corrosion chemical pickling is not only accepted the style of electricity connected. Chemical cleaning effect is very fast, organized well in advance as long as it will not cause any pollution. Cleaning spiral very serious altercation pace, must be detailed.
Spiral mainly used in water engineering, petrochemical industry, chemical industry, power industry, agricultural irrigation, urban construction, is the development of the 20 key products. For the transport of liquids: water supply, drainage, sewage treatment works, lose mud, sea water. For gas transportation: gas, steam, liquefied petroleum gas. For structural purposes: as piling pipe for bridges; docks, roads, building structure pipe, marine piling pipe.
Also known as spiral or helical spiral piling pipe, is a low-carbon steel or low alloy steel strip at a certain angle of the helix (called molding angle) rolled into a tube, then welded together to form the tube, it can be produced with a narrow strip of large diameter steel pipe. Spiral is mainly used for oil and gas pipelines, its diameter * thickness expressed. Spiral single-sided and double-sided welding welding, pipe should ensure that hydrostatic test, weld tensile strength and cold performance to meet the requirements.
Spiral mainly used in water engineering, petrochemical industry, chemical industry, power industry, agricultural irrigation, urban construction, is the development of the 20 key products. For the transport of liquids: water supply, drainage, sewage treatment works, lose mud, sea water. For gas transportation: gas, steam, liquefied petroleum gas. For structural purposes: as piling pipe for bridges; docks, roads, building structure pipe, marine piling pipe.
Also known as spiral or helical spiral piling pipe, is a low-carbon steel or low alloy steel strip at a certain angle of the helix (called molding angle) rolled into a tube, then welded together to form the tube, it can be produced with a narrow strip of large diameter steel pipe. Spiral is mainly used for oil and gas pipelines, its diameter * thickness expressed. Spiral single-sided and double-sided welding welding, pipe should ensure that hydrostatic test, weld tensile strength and cold performance to meet the requirements.
How to detect the hardness of high-pressure boiler tubes
High-pressure boiler tubes is to determine the hardness of the main elements of its quality, if we want to accurately detect the high-pressure boiler tubes hardness, then the first point must first understand 20G high-pressure boiler pipe mechanical properties, as this is affecting their deformation , stamping, cutting and other processing performance and quality problems. So first of its hardness testing should detect its mechanical properties. Typically using a tensile test and hardness test these two methods do testing. Tensile test refers to high-pressure boiler tube sample preparation, but also in a tensile testing machine until fracture tensile Admiral, so you can detect the high-pressure boiler tubes tensile strength, yield strength, elongation rate and section shrinkage. In metal material tensile test is the most commonly used detection method is not easy for many hardness test, the tensile test must be carried out. Relatively high hardness test method, there scarification, pressed into the method, dynamic method, etc., as compared with the tensile test, hardness test is relatively simple and more.
Glass smooth kneading agent in the production of seamless steel tubes in the use of heat
Selection of traditional steel kneading produce graphite (flake graphite and oil, such as tar or grease mixed into the paint) as a lubricant. However, the disadvantage of graphite lubricant are: ① large thermal conductivity, thermal insulation is poor, tool and die temperature, wear fast, kneading long goods difficult. ② simple cause merchandise by carbon, stainless steel simple when kneading intergranular corrosion occurs, it is necessary to remove the kneading after the carburized layer, the results of increased metal consumption. ③ often cause environmental pollution.
Comparison of glass and graphite lubricant, its strengths are: ① glass thermal conductivity, to avoid excessive cooling billet appearance together can also play the role of maintenance workers die. ② with excellent smooth function, the choice of a large and progressive than kneading kneading speed kneading machine can then be expanded scale production of goods. ③ glass Glazes good chemical stability, does not result in arrangements shortcomings. ④ can easily change the ratio of the glass lubricant to obtain a different physical features (such as softening point, viscosity, etc.) to different materials used to knead the product requirements. ⑤ When the use of glass as a lubricant can be maintained clean. I fear, glass smooth agent strengths obvious. Many foreign research results indicate, kneading steel use glass Glazes work best.
Kneading the need for a smooth tube parts are: kneading molding, kneading drum and the mandrel three parts.
(1) kneading mode Smooth: Smooth mold pressed into the glass frit used to pad the way, that is, before kneading the glass mat is placed between the mold and the billet. To ensure the continuation of glass mat can soften the appearance of conflict, the demand of glass mat shape and mold Kong imports cone and match the shape of the blank ends. Glass mat tube diameter typically smaller in diameter than the kneading 3 ~ 5mm. Glass mat is less than or equal to the diameter of the hole diameter of the die hole. The thickness of the glass mat is usually taken blank length of 4% to 8%.
(2) kneading the smooth tube and the mandrel: kneading a smooth tube and the mandrel should be used in low softening point glass frit coated small particle size within the bore of the billet and the outer appearance. In addition, it is possible to wrap wrapped with a glass cloth and the appearance of the blank of the glass cloth of the way around the mandrel.
(3) appearance of the glass film tube removed: as conching glass lubricant used, kneading the exterior appearance of the residual steel having a thickness of 20 ~ 50μm glass film, the nature of the hard and brittle, detrimental to future processing and use, it is necessary to eradicate. Eradication measures have mechanical and chemical methods. Mechanical methods are blasting, water-cooled and tensile straightening and other methods. Elimination of the use of chemical glass film, since the appearance of the pipe lubricant residue on the glass has a high chemical stability, elimination of which needs an alkali solution or acid solution used. Inadequacies of pickling of various steel materials is that the erosion of large, the appearance may happen pickling steel, especially for larger carbon steel pipe erosion, and thus the utilization was limited. Currently selected pH joint eradication method.
Comparison of glass and graphite lubricant, its strengths are: ① glass thermal conductivity, to avoid excessive cooling billet appearance together can also play the role of maintenance workers die. ② with excellent smooth function, the choice of a large and progressive than kneading kneading speed kneading machine can then be expanded scale production of goods. ③ glass Glazes good chemical stability, does not result in arrangements shortcomings. ④ can easily change the ratio of the glass lubricant to obtain a different physical features (such as softening point, viscosity, etc.) to different materials used to knead the product requirements. ⑤ When the use of glass as a lubricant can be maintained clean. I fear, glass smooth agent strengths obvious. Many foreign research results indicate, kneading steel use glass Glazes work best.
Kneading the need for a smooth tube parts are: kneading molding, kneading drum and the mandrel three parts.
(1) kneading mode Smooth: Smooth mold pressed into the glass frit used to pad the way, that is, before kneading the glass mat is placed between the mold and the billet. To ensure the continuation of glass mat can soften the appearance of conflict, the demand of glass mat shape and mold Kong imports cone and match the shape of the blank ends. Glass mat tube diameter typically smaller in diameter than the kneading 3 ~ 5mm. Glass mat is less than or equal to the diameter of the hole diameter of the die hole. The thickness of the glass mat is usually taken blank length of 4% to 8%.
(2) kneading the smooth tube and the mandrel: kneading a smooth tube and the mandrel should be used in low softening point glass frit coated small particle size within the bore of the billet and the outer appearance. In addition, it is possible to wrap wrapped with a glass cloth and the appearance of the blank of the glass cloth of the way around the mandrel.
(3) appearance of the glass film tube removed: as conching glass lubricant used, kneading the exterior appearance of the residual steel having a thickness of 20 ~ 50μm glass film, the nature of the hard and brittle, detrimental to future processing and use, it is necessary to eradicate. Eradication measures have mechanical and chemical methods. Mechanical methods are blasting, water-cooled and tensile straightening and other methods. Elimination of the use of chemical glass film, since the appearance of the pipe lubricant residue on the glass has a high chemical stability, elimination of which needs an alkali solution or acid solution used. Inadequacies of pickling of various steel materials is that the erosion of large, the appearance may happen pickling steel, especially for larger carbon steel pipe erosion, and thus the utilization was limited. Currently selected pH joint eradication method.
Chemical etching of spiral piling pipe
In nature, the material will dissolve in a solution are well known specific phenomena, such as: sugar, salt will dissolve in water, or a plurality of metal or non-metal will dissolve in hydrochloric acid. Sometimes we can take advantage of these features in the manufacturing method, for example: the use of ferric chloride to etch the copper art or circuit board. However, the use of materials in construction, most of the coil is still considered prevention of corrosion of spiral piling pipe.
In general, the metal, the solution is most likely to erode the position of the grain and grain joining the Department, which is the grain boundary, and then continued to grow, sometimes chemical corrosion or the formation of compounds with the environment changes, it may be accompanied by electrochemical etching from, of course, if this is the case, the corrosion phenomenon will become more complicated.
1. Selective filter
Some metal alloy materials under special circumstances, one or more elements which are selectively filtered easily (leach) or called corrosion, and become porous residues, thereby reducing the mechanical properties, such phenomenon called selective filter. This phenomenon, related to the nature and metal, such as zinc contained in the brass at high temperatures will be dissolved in the aqueous solution of salts, produced dezincification (dezincification) localized corrosion phenomena, and the lack of zinc position, so that yellow copper becomes porous structure and becomes very fragile.
2. Graphite corrosion
Graphite corrosion is another example of a similar selective etching, flake graphite cast iron is staggered in the iron-based organizations, if placed in water or soil, the iron will of the graphite anode compared with the more cathodic the Therefore part of the iron will corrode, and the formation of a porous appearance, the gray cast iron pipes, have a positive corrosion measures, if properly buried, prone to leakage or explosion event.
Chemical corrosion prevention and control is extremely difficult, the coating material is a way to avoid the material with the solution (especially easy to play, with pH solution) contact is another way to solve. If it must be used in an environment in solution must be considered when selecting a material resistant to chemical corrosion. For example: In order to suppress the phenomenon of dezincification brass, we can more than 15% zinc brass, add about 1% Sn Sb, in order to resist such corrosion and increases strength. Such tin-containing brass include: Navy brass (naval brass), the sea will be brass (admiralty metal) are examples of it.
In general, the metal, the solution is most likely to erode the position of the grain and grain joining the Department, which is the grain boundary, and then continued to grow, sometimes chemical corrosion or the formation of compounds with the environment changes, it may be accompanied by electrochemical etching from, of course, if this is the case, the corrosion phenomenon will become more complicated.
1. Selective filter
Some metal alloy materials under special circumstances, one or more elements which are selectively filtered easily (leach) or called corrosion, and become porous residues, thereby reducing the mechanical properties, such phenomenon called selective filter. This phenomenon, related to the nature and metal, such as zinc contained in the brass at high temperatures will be dissolved in the aqueous solution of salts, produced dezincification (dezincification) localized corrosion phenomena, and the lack of zinc position, so that yellow copper becomes porous structure and becomes very fragile.
2. Graphite corrosion
Graphite corrosion is another example of a similar selective etching, flake graphite cast iron is staggered in the iron-based organizations, if placed in water or soil, the iron will of the graphite anode compared with the more cathodic the Therefore part of the iron will corrode, and the formation of a porous appearance, the gray cast iron pipes, have a positive corrosion measures, if properly buried, prone to leakage or explosion event.
Chemical corrosion prevention and control is extremely difficult, the coating material is a way to avoid the material with the solution (especially easy to play, with pH solution) contact is another way to solve. If it must be used in an environment in solution must be considered when selecting a material resistant to chemical corrosion. For example: In order to suppress the phenomenon of dezincification brass, we can more than 15% zinc brass, add about 1% Sn Sb, in order to resist such corrosion and increases strength. Such tin-containing brass include: Navy brass (naval brass), the sea will be brass (admiralty metal) are examples of it.
New application of spiral steel pipe
Spiral steel pipe in the traditional applications based on the new application has been added, which makes the usefulness of spiral steel pipe more rich, and also reduces the cost of using the spiral pipe. Radio frequency sensors to provide 200 volts, 50 amps of current through the spiral steel pipe, experimental samples by induction heating effect. The coil itself does not get hot, but the experimental samples will be significant fever. In the heating temperature exceeds arc melting machine, radio frequency sensors will provide more control so that scientists can adjust the composition ratio of alloy detailed.
Radio frequency sensor spiral steel pipe in a matter of seconds on the experimental sample heating 800-1000 degrees Celsius, the goal of this process is below the melting point of the sample heating, the sample atoms to form a specific part of the crystal structure. This is reinforced in the crystal structure established under the dendrite breakthrough technology.
Using double-sided spiral submerged arc spiral pipe welding technology, the narrowband (board) volume continuous welded steel pipe. In our natural gas and other long-distance gas pipeline project has been widely used, is our long-distance gas pipeline project using the main tube. Spiral steel pipes are widely used in natural gas, petroleum, chemical, electric power, heat, water, steam heating, hydropower penstock, construction piling pipe, power generation, water and other long-distance pipelines and piling, dredging, bridges, steel, etc. engineering fields.
Radio frequency sensor spiral steel pipe in a matter of seconds on the experimental sample heating 800-1000 degrees Celsius, the goal of this process is below the melting point of the sample heating, the sample atoms to form a specific part of the crystal structure. This is reinforced in the crystal structure established under the dendrite breakthrough technology.
Using double-sided spiral submerged arc spiral pipe welding technology, the narrowband (board) volume continuous welded steel pipe. In our natural gas and other long-distance gas pipeline project has been widely used, is our long-distance gas pipeline project using the main tube. Spiral steel pipes are widely used in natural gas, petroleum, chemical, electric power, heat, water, steam heating, hydropower penstock, construction piling pipe, power generation, water and other long-distance pipelines and piling, dredging, bridges, steel, etc. engineering fields.
Tuesday, June 25, 2013
Straight seam steel pipe heat treatment after welding
Straight seam steel pipe weld heat treatment is a new technique to eliminate residual stress. Preheated before welding the material to a heat treatment temperature after the welding process and welding pieces of heating was continued to maintain this temperature, the soldering is completed using heat insulation cotton to its slow cooling. This method can effectively reduce residual stress and improve the stress corrosion resistance of metals.
NDT weld inside the pipe in the water supply as part of large steel works, especially the thickness t = 30mm steel tube is used as a pipe bridge, both to withstand the water pressure, but also the burden of weight and water from the pipe forming moment, so the welding quality requirements are particularly high. For pipe bridge of t = 30mm thick with a large-diameter steel pipe, the longitudinal seam and girth welds belong to a class, require 100% of X-ray film examination and 100% of the ultrasonic flaw detection; while the thickness t = 24mm buried pipe, belongs to a class of longitudinal seam welding, for 20% of the X-ray film examination and 50% of the ultrasonic flaw inspection.
Heat treatment after welding can reduce the residual stress, and heat treatment temperature is higher, the better to eliminate the residual stress. Large diameter steel pipe weld heat treatment can effectively improve the large-diameter steel pipe stress corrosion resistance, heat treatment temperature is higher, increasing resistance to stress corrosion is more significant. Diffusion of metal carbide coating technology is the workpiece on special media, the diffusion layer is formed on the surface of several microns to several tens of micrometers of the metal carbide layer. Large diameter steel pipe anti-corrosion of buried pipes and tubes inside out corrosion, are used to spiral piling pipe, spraying compressive strength of not less than 30N/mm2 cement mortar lining.
NDT weld inside the pipe in the water supply as part of large steel works, especially the thickness t = 30mm steel tube is used as a pipe bridge, both to withstand the water pressure, but also the burden of weight and water from the pipe forming moment, so the welding quality requirements are particularly high. For pipe bridge of t = 30mm thick with a large-diameter steel pipe, the longitudinal seam and girth welds belong to a class, require 100% of X-ray film examination and 100% of the ultrasonic flaw detection; while the thickness t = 24mm buried pipe, belongs to a class of longitudinal seam welding, for 20% of the X-ray film examination and 50% of the ultrasonic flaw inspection.
Heat treatment after welding can reduce the residual stress, and heat treatment temperature is higher, the better to eliminate the residual stress. Large diameter steel pipe weld heat treatment can effectively improve the large-diameter steel pipe stress corrosion resistance, heat treatment temperature is higher, increasing resistance to stress corrosion is more significant. Diffusion of metal carbide coating technology is the workpiece on special media, the diffusion layer is formed on the surface of several microns to several tens of micrometers of the metal carbide layer. Large diameter steel pipe anti-corrosion of buried pipes and tubes inside out corrosion, are used to spiral piling pipe, spraying compressive strength of not less than 30N/mm2 cement mortar lining.
Seamless steel pipe application in buried insulating pipe line
Heating pipe insulation will be taken before using the handle, which is also in the delivery of cold or hot water, steam, to reduce heat loss, in which the work will be used spiral piling pipe generally there are some projects will use seamless steel tube, which seamlessly hot and cold rolled tubes of two general I produced the heating pipe heating pipe insulation used in the work will be used seamless steel pipe, this pipe is used in the current heating project the most common pipe insulation in the production what equipment may be used: steel shot blasting machine, three PE winding equipment, PE pipe black and yellow jacket pulling machines, sand-blasting equipment, low pressure polyurethane fat Kee machine, foam platform, fiberglass winding machine, two PE coating, cement mortar spraying machines and other corrosion insulation supporting test equipment.
Anti-corrosion pipe insulation pipe deformation under external force, stability, anti-fatigue, etc. are likely to have an adverse effect on performance. In the hot-rolled steel products for processing, the pipe thickness and edge width not control this. Since the beginning of the expansion and contraction rolled out even the length, thickness are achieved and finally cooled or there will be some negative difference, this negative difference edge width is wider, thicker the performance will be more apparent. Relatively speaking GB spiral steel and seamless during transport are relatively stable, so the two steel pipe insulation work in the application of the more common tube.
Anti-corrosion pipe insulation pipe deformation under external force, stability, anti-fatigue, etc. are likely to have an adverse effect on performance. In the hot-rolled steel products for processing, the pipe thickness and edge width not control this. Since the beginning of the expansion and contraction rolled out even the length, thickness are achieved and finally cooled or there will be some negative difference, this negative difference edge width is wider, thicker the performance will be more apparent. Relatively speaking GB spiral steel and seamless during transport are relatively stable, so the two steel pipe insulation work in the application of the more common tube.
Heat shrinkable belt anti-corrosion steel pipe application in interface pipe fittings
Heat-shrinkable polyethylene heat shrink tape, polyethylene heat shrinkable tape, by radiation cross-linked polyethylene sheet material (substrate) and specialty hot melt composite made of corrosion-resistant materials, mainly for the manufacture of heat shrinkable tape anti-corrosion steel pipe. Divided into cylindrical tablets with a fixed structure (often called corrugated type or open type heat shrinkable sleeve) and band structure two kinds of commonly used styles, shrinkage ge; 15. The radiation crosslinking of modified polyethylene sheet material (substrate) and ordinary polyethylene, high mechanical strength, and long life, corrosion resistance, aging resistance, resistance to environmental stress cracking, composite heat melt adhesive has strong bonding and good sealing characteristics, is ideal for making anti-corrosion steel pipe anti-corrosion materials, anti-corrosion steel pipe is mainly used 3pe for some reason can not produce a very good substitute corrosion process or corrosion at the interface .
Mainly used in oil, gas, chemical, city oil pipeline and gas pipeline network and other anti-corrosion steel pipe mending, mending and interfaces, elbows, tees, etc. wound antiseptic; insulation pipe (stuck pipe) drainage and other engineering PE, PVC pipe joint seals fixed and so on. Different uses for the project, with a variety of specifications of specific products, divided into anticorrosion mouth, interfaces fixed, water seepage type, rust protection type, and other categories, customers can choose according to actual engineering requirements. With high mechanical strength, anti-aging ability, good sealing performance, corrosion-resistant, easy to use, save labor and many other advantages.
Shrink band width of 50mm to 600mm, heat shrinkable tape of any length, the construction site according to the diameter size, the width of cut for any size. This flexibility helps customers reduce inventory waste and construction input costs, facilitate project management.
Mainly used in oil, gas, chemical, city oil pipeline and gas pipeline network and other anti-corrosion steel pipe mending, mending and interfaces, elbows, tees, etc. wound antiseptic; insulation pipe (stuck pipe) drainage and other engineering PE, PVC pipe joint seals fixed and so on. Different uses for the project, with a variety of specifications of specific products, divided into anticorrosion mouth, interfaces fixed, water seepage type, rust protection type, and other categories, customers can choose according to actual engineering requirements. With high mechanical strength, anti-aging ability, good sealing performance, corrosion-resistant, easy to use, save labor and many other advantages.
Shrink band width of 50mm to 600mm, heat shrinkable tape of any length, the construction site according to the diameter size, the width of cut for any size. This flexibility helps customers reduce inventory waste and construction input costs, facilitate project management.
Seamless and welded pipe related problem
From the world's point of view, the past 15 years, the international industrial countries essentially no new seamless unit. In these countries, the proportion of steel pipe, seamless pipe about 30%, about 70% of pipe, welded pipe proportion is rising momentum. The number of products on our 2005 production was 15.67 million tons pipe, seamless pipe is 10.47 million tons, ranking first in the world; in product grade, high levels of seamless living, at the core, while living in the high-end pipe level, at the end edge of the core.
In OCTG, for example, continued to hold the leading position in seamless. Currently, the world production of ERW OCTG about 400 million tons, accounting for 50% of total oil casing. U.S. oil production process using ERW casing more than 50% of its total production, 76.8% of Japan's oil casing that can be used ERW pipe. At this stage, foreign ERW casing used, there has been a mature steel grade H40, J55, N89, L80, etc. In 2005, China produced about 1.8 million tons of oil well pipes, including seamless 1.62 million tons, accounting for 90%, ERW pipe 180,000 tons, accounting for 10%; and ERW pipe of steel grade is basically J55 level, great room for development .
As raw material production capacity greatly STRIP excess fierce market competition has become the impetus for innovation. High-speed broadband and domestic manufacturers are also in the pipeline, oil country tubular steel and weathering steel used in construction direction. Meanwhile, strip coil prices return to the rational, the current specifications of the same species ERW oil casing products cheaper than seamless pipe products about 800-1000 yuan per ton, profits also contributed to the spread of ERW pipe to the development of high-end products , which is bound to raise the level of technology of seamless pipes.
Seamless steel structure still dominated area, it is because the building is not only strength requirements tube, and has stiffness requirements. The advantage of having a thick-walled seamless pipe, can achieve stiffness requirements, round steel pipe To enter, they have to develop thick-walled tube. Currently, Φ114mmERW pipe wall thickness can reach the general 7mm. ERW welded pipe production rectangular tube wall thickness of less than 20mm in general, so the specifications for steel 400mm × 400mm-200mmx200mm-based, mostly as a steel rod.
In the field of boiler tubes, ERW pipe are seamless treatment process, still only restricted for low and medium pressure boiler tubes; seamless ranked high pressure boiler tube at this level, but would like the nuclear island tube, supercritical point ( such as pressure 24.2MPa, temperature 600 ℃) pipe direction. Pipe production process is "cold", and seamless production process is "thermal processing", pipe is more conducive to energy conservation and environmental protection. Hot-rolled seamless steel pipe production process 2-3 times to go through intermediate heating, a second piercing rolling, 1 and 1 finished blooming heat treatment, the process of energy consumption and environmental impact, as implemented Green metallurgical strategic objectives must address the issue. Therefore, to make seamless steel tube heat delivery technology, continuous casting round billet technology and even seamless shortened process technology research and development, independent innovation is an important issue. Only by doing so can we find significantly reduce the cost of production of seamless steel tubes, is also conducive to energy conservation and environmental protection, low-cost response to the challenges of pipe; Only by doing so can break a seamless technology with Chinese characteristics, the development of road.
In OCTG, for example, continued to hold the leading position in seamless. Currently, the world production of ERW OCTG about 400 million tons, accounting for 50% of total oil casing. U.S. oil production process using ERW casing more than 50% of its total production, 76.8% of Japan's oil casing that can be used ERW pipe. At this stage, foreign ERW casing used, there has been a mature steel grade H40, J55, N89, L80, etc. In 2005, China produced about 1.8 million tons of oil well pipes, including seamless 1.62 million tons, accounting for 90%, ERW pipe 180,000 tons, accounting for 10%; and ERW pipe of steel grade is basically J55 level, great room for development .
As raw material production capacity greatly STRIP excess fierce market competition has become the impetus for innovation. High-speed broadband and domestic manufacturers are also in the pipeline, oil country tubular steel and weathering steel used in construction direction. Meanwhile, strip coil prices return to the rational, the current specifications of the same species ERW oil casing products cheaper than seamless pipe products about 800-1000 yuan per ton, profits also contributed to the spread of ERW pipe to the development of high-end products , which is bound to raise the level of technology of seamless pipes.
Seamless steel structure still dominated area, it is because the building is not only strength requirements tube, and has stiffness requirements. The advantage of having a thick-walled seamless pipe, can achieve stiffness requirements, round steel pipe To enter, they have to develop thick-walled tube. Currently, Φ114mmERW pipe wall thickness can reach the general 7mm. ERW welded pipe production rectangular tube wall thickness of less than 20mm in general, so the specifications for steel 400mm × 400mm-200mmx200mm-based, mostly as a steel rod.
In the field of boiler tubes, ERW pipe are seamless treatment process, still only restricted for low and medium pressure boiler tubes; seamless ranked high pressure boiler tube at this level, but would like the nuclear island tube, supercritical point ( such as pressure 24.2MPa, temperature 600 ℃) pipe direction. Pipe production process is "cold", and seamless production process is "thermal processing", pipe is more conducive to energy conservation and environmental protection. Hot-rolled seamless steel pipe production process 2-3 times to go through intermediate heating, a second piercing rolling, 1 and 1 finished blooming heat treatment, the process of energy consumption and environmental impact, as implemented Green metallurgical strategic objectives must address the issue. Therefore, to make seamless steel tube heat delivery technology, continuous casting round billet technology and even seamless shortened process technology research and development, independent innovation is an important issue. Only by doing so can we find significantly reduce the cost of production of seamless steel tubes, is also conducive to energy conservation and environmental protection, low-cost response to the challenges of pipe; Only by doing so can break a seamless technology with Chinese characteristics, the development of road.
DSAW pre-welding technology
LSAW pre-welding technology in the pipeline construction, oil and gas pipelines is toward large-diameter high pressure transmission and submarine pipelines thick direction of development, a growing number of pipeline requests using DSAW steel pipe. As China's few Tachih submerged arc welded pipe production line imported production, LSAW grasp advanced welding technology is particularly important.
Pre-welding technology status
Presoldering LSAW steel pipe welding work is part of the seam along the length of it forming a "shallow weld" is LSAW pipe production is one of the special process. In the early years of LSAW pipe production is not pre-welded, welded pipe mill until the second-generation uoe began to emerge in pre-welder, but this time the pre-welded to intermittent welding, spacing of about 300mm, welded steel tube mill to uoe Development of the third generation, pre-weld has been greatly focused and development, has gradually form into another form is not at this stage of the pre-welding technology welding technology for the contemporary pre-foundation.
Pre-process welding work
Presoldering, the first steel tube for commissure, followed by another gas shielded arc welding, seam welding conditions and simultaneous welding quality monitoring and feedback. Specific work process: to accept imports of roller tube - adjust the seat tube opening - Conveying Equipment delivery tube tube leaves commissure - confirm commissure quality - preliminary welding torch landed - start tracking laser tracker - open the protective gas and the cooling water valve - start welding (welding speed tube to feed) _ - to stop the terminal arc welding - Hysteresis Shutdown Protection Gas - torch rising return - pass tube down procedure. This, a pre-weld cycle is completed. In the above process, adjust seat tube opening, refers to the openings on the seat adjusted to request seats, seat ordinary is 12 o'clock, this work can be electrically controlled system camera surveillance system. Confirm commissure quality, is on the wrong side seam of the amount recognized in the seam gaps, etc., can be confirmed as long as the tracking and weld seam. In order to ensure the welding quality of the welding starts, check the specific use of the torch, clean spatter on the torch may be appropriate to spray some anti-spatter agent. Pre-welding arcs and arc-quenching ordinary Kai Kai arc board and board for extinction. Approximately 80mm tube end forming within the scope of the pre-welding seam by hand after the end of GMAW welding.
Pre-welding technology status
Presoldering LSAW steel pipe welding work is part of the seam along the length of it forming a "shallow weld" is LSAW pipe production is one of the special process. In the early years of LSAW pipe production is not pre-welded, welded pipe mill until the second-generation uoe began to emerge in pre-welder, but this time the pre-welded to intermittent welding, spacing of about 300mm, welded steel tube mill to uoe Development of the third generation, pre-weld has been greatly focused and development, has gradually form into another form is not at this stage of the pre-welding technology welding technology for the contemporary pre-foundation.
Pre-process welding work
Presoldering, the first steel tube for commissure, followed by another gas shielded arc welding, seam welding conditions and simultaneous welding quality monitoring and feedback. Specific work process: to accept imports of roller tube - adjust the seat tube opening - Conveying Equipment delivery tube tube leaves commissure - confirm commissure quality - preliminary welding torch landed - start tracking laser tracker - open the protective gas and the cooling water valve - start welding (welding speed tube to feed) _ - to stop the terminal arc welding - Hysteresis Shutdown Protection Gas - torch rising return - pass tube down procedure. This, a pre-weld cycle is completed. In the above process, adjust seat tube opening, refers to the openings on the seat adjusted to request seats, seat ordinary is 12 o'clock, this work can be electrically controlled system camera surveillance system. Confirm commissure quality, is on the wrong side seam of the amount recognized in the seam gaps, etc., can be confirmed as long as the tracking and weld seam. In order to ensure the welding quality of the welding starts, check the specific use of the torch, clean spatter on the torch may be appropriate to spray some anti-spatter agent. Pre-welding arcs and arc-quenching ordinary Kai Kai arc board and board for extinction. Approximately 80mm tube end forming within the scope of the pre-welding seam by hand after the end of GMAW welding.
Difference between hot stretch reducing pipe and the Longitudinal seam welded pipe
Because by its manufacturing process constraints, the cost of production of seamless steel tube has been high, resulting in the gradual decline of its economic benefits. With the Chinese metallurgical industry advances in technology, new product instead of seamless steel pipe hot stretch reducing began to emerge. Here is the difference between the new product and Longitudinal:
1, seam welded directly determines the quality of the quality, but also where the biggest difference between ERW and seamless. Longitudinal high-frequency welding, seam straight sets carbon can not be eliminated, the weld interface together with the parent only, and not completely fused into one, unable to withstand the test of time and pressure. Hot stretch reducing high-frequency welded steel pipes go through the whole heating temperature of 800 degrees, the overall annealing, and then open the change process, through this series of processes, the weld performance has the same parent organization, completely fused into one , well done from a seam to the seamless transition.
2, the process resulting in a product of different quality differences, hot stretch reducing high frequency welded steel pipes in a Longitudinal also carried out after the process is not carried out, both inside and outside burr removal online. The existence glitch affects the flow of fluid inside the tube, blocking the flow of burr Neptune Casino normal flow of the body, resulting in whirlpool. According to principles of fluid mechanics, the weld must increase local compression, discontinuity of the pipe safety factor is also greatly reduced, hot stretch reducing steel production process to take full account of the risks that exist burr, burr removal to limit, thus make uniform thickness, seamless appearance with no difference. So from this point of view, hot stretch reducing pipe joints from having also completed a seamless transition to.
Hot stretch reducing pipe in Longitudinal carried out on the basis of clear internal and external burrs online, the overall heating type variable and a series of new processing technology, so that it has been a qualitative leap in the field of the widespread use of high-pressure, the Longitudinal only limited water under low pressure gas transmission.
1, seam welded directly determines the quality of the quality, but also where the biggest difference between ERW and seamless. Longitudinal high-frequency welding, seam straight sets carbon can not be eliminated, the weld interface together with the parent only, and not completely fused into one, unable to withstand the test of time and pressure. Hot stretch reducing high-frequency welded steel pipes go through the whole heating temperature of 800 degrees, the overall annealing, and then open the change process, through this series of processes, the weld performance has the same parent organization, completely fused into one , well done from a seam to the seamless transition.
2, the process resulting in a product of different quality differences, hot stretch reducing high frequency welded steel pipes in a Longitudinal also carried out after the process is not carried out, both inside and outside burr removal online. The existence glitch affects the flow of fluid inside the tube, blocking the flow of burr Neptune Casino normal flow of the body, resulting in whirlpool. According to principles of fluid mechanics, the weld must increase local compression, discontinuity of the pipe safety factor is also greatly reduced, hot stretch reducing steel production process to take full account of the risks that exist burr, burr removal to limit, thus make uniform thickness, seamless appearance with no difference. So from this point of view, hot stretch reducing pipe joints from having also completed a seamless transition to.
Hot stretch reducing pipe in Longitudinal carried out on the basis of clear internal and external burrs online, the overall heating type variable and a series of new processing technology, so that it has been a qualitative leap in the field of the widespread use of high-pressure, the Longitudinal only limited water under low pressure gas transmission.
Friday, June 21, 2013
The role of anti-corrosion paint coating steel
We all know that as long as steel or humid atmospheres contaminated by environmental impact will suffer corrosion, chalking and eventually end life. Therefore, the steel structure in the coating process, the primary consideration is the condition of its construction to ensure construction environmental norms. Steel used in the building structure more and more, many large convention centers, stadiums, airport terminals, steel tower, adopted as the main structure.
To ensure the integrity of steel buildings, steel structures show artistic influence, the use of anti-corrosion coatings for paint protection is economically feasible, the service life can reach more than 15a. If using metal thermal spray coatings and heavy duty double protection, service life can reach more than 25a.
Steel is an important structure of modern building materials, high strength, stable performance, good toughness, easy to manufacture, suitable for mass production, quality control and easy to install quickly. Coating in steel building design, not only to consider the long-term life of anti-corrosion coatings, while also taking into account environmental protection. Heavy duty coatings for steel structures to reflect the performance, aesthetics and environmental protection among the best combination.
To ensure the integrity of steel buildings, steel structures show artistic influence, the use of anti-corrosion coatings for paint protection is economically feasible, the service life can reach more than 15a. If using metal thermal spray coatings and heavy duty double protection, service life can reach more than 25a.
Steel is an important structure of modern building materials, high strength, stable performance, good toughness, easy to manufacture, suitable for mass production, quality control and easy to install quickly. Coating in steel building design, not only to consider the long-term life of anti-corrosion coatings, while also taking into account environmental protection. Heavy duty coatings for steel structures to reflect the performance, aesthetics and environmental protection among the best combination.
Limitations of spiral steel pipe
Spiral pipe also has its own shortcomings, spiral steel pipe hollow section with a large number of channels for transporting fluids, such as the transportation of oil, natural gas, coal gas, water and some solid materials, pipes and so on. Steel pipe and solid steel bar, etc. compared to the same torsional strength in bending, lighter, which is an economic cross-section steel, widely used in the manufacture of structural parts and mechanical parts, such as piling pipe, automotive drive shafts, bicycle rack and construction using steel scaffolding.
With steel pipe manufacturing annular parts, can improve material utilization, simplify the manufacturing process, saving material and machining time, such as bearing rings, jack sets, has been widely used to make steel. Steel or a variety of conventional weapons indispensable material, barrel, barrel, etc. to make steel. By cross-sectional shape of the pipe can be divided into tube and shaped tubes. Since the perimeter of equal conditions, the maximum area of a circle with a circular tube can carry more fluid. In addition, the circular cross section to withstand internal or external radial pressure, the force is uniform, so the vast majority of the pipe is pipe.
However, the tube also has some limitations, such as by plane bending conditions, the tube is not as good as square, rectangular tube bending strength, some of the farm skeleton, steel and wood furniture to common square and rectangular pipes. According to different uses should also have other cross-sectional shapes of the shaped pipe.
With steel pipe manufacturing annular parts, can improve material utilization, simplify the manufacturing process, saving material and machining time, such as bearing rings, jack sets, has been widely used to make steel. Steel or a variety of conventional weapons indispensable material, barrel, barrel, etc. to make steel. By cross-sectional shape of the pipe can be divided into tube and shaped tubes. Since the perimeter of equal conditions, the maximum area of a circle with a circular tube can carry more fluid. In addition, the circular cross section to withstand internal or external radial pressure, the force is uniform, so the vast majority of the pipe is pipe.
However, the tube also has some limitations, such as by plane bending conditions, the tube is not as good as square, rectangular tube bending strength, some of the farm skeleton, steel and wood furniture to common square and rectangular pipes. According to different uses should also have other cross-sectional shapes of the shaped pipe.
Spiral corrosion technology
Since the quality of the individual spiral welded pipe is relatively large, it must be stacked in the outdoors, but this will be difficult to avoid the sun and rain, so the rusty spiral welded piling pipe has been plagued by storage time and conditions. So we have the need for knowledge about the spiral welded pipe rust comprehensive answers.
Spiral welded wire brushes and other tools used primarily on the surface of polished steel, spiral welded pipe cleaning and preheating can remove loose or warped oxide, rust, welding slag. Hand tools rust can reach Sa2 grade, spiral power tools rust Sa3 level can be achieved, if the steel surface firmly attached to the iron skin, the effect is not ideal tools rust, anti-corrosion construction required to reach the depth of anchor pattern. Acid by solvent, emulsion cleaning fluid pressure welded steel tube (pipe) surfaces to achieve the removal of oil, grease, dust, lubricants and similar organic matter, but it can not remove the steel surface rust, oxide, flux, etc., Therefore, in the production of corrosion only as an adjunct.
Generally use two methods to do chemical and electrolytic pickling treatment, pipeline corrosion using only chemical pickling can descaling, rust, old paint, sometimes used as a sand blasting after reprocessing. Although chemical cleaning can achieve a certain surface cleanliness and roughness, but the anchor pattern shallow, and easy on the environment caused by pollution stacking spiral welded pipe. Rational use of means to clean up the rusty pipe fittings for a long time when the guarantee services in the production and create more production efficiency.
Spiral welded wire brushes and other tools used primarily on the surface of polished steel, spiral welded pipe cleaning and preheating can remove loose or warped oxide, rust, welding slag. Hand tools rust can reach Sa2 grade, spiral power tools rust Sa3 level can be achieved, if the steel surface firmly attached to the iron skin, the effect is not ideal tools rust, anti-corrosion construction required to reach the depth of anchor pattern. Acid by solvent, emulsion cleaning fluid pressure welded steel tube (pipe) surfaces to achieve the removal of oil, grease, dust, lubricants and similar organic matter, but it can not remove the steel surface rust, oxide, flux, etc., Therefore, in the production of corrosion only as an adjunct.
Generally use two methods to do chemical and electrolytic pickling treatment, pipeline corrosion using only chemical pickling can descaling, rust, old paint, sometimes used as a sand blasting after reprocessing. Although chemical cleaning can achieve a certain surface cleanliness and roughness, but the anchor pattern shallow, and easy on the environment caused by pollution stacking spiral welded pipe. Rational use of means to clean up the rusty pipe fittings for a long time when the guarantee services in the production and create more production efficiency.
Advantages and disadvantages of large diameter hot-rolled seamless steel pipe
Large-diameter rolled seamless steel tube in terms relative to the cold, cold rolling is carried out at a temperature below the recrystallization rolling, the hot rolling is carried out at a temperature above the recrystallization rolling.
Benefits:
Large-diameter hot-rolled seamless steel pipe can damage the ingot casting organizations, grain refinement of steel and eliminate defects in the microstructure, so that the dense tissue steel, mechanical properties are improved. This improvement is mainly reflected in the rolling direction, so that the steel is no longer certain extent isotropic; pouring bubbles formed cracks and porosity, but also in under the action of high temperature and pressure welding.
Disadvantages:
1 After hot rolling, the steel inside the non-metallic inclusions (mainly sulfides and oxides, and silicates) is pressed into the sheet, delamination (interlayer) phenomenon. Layered in the thickness direction of the steel in tension performance deteriorated significantly, and may occur in the weld shrinkage interlayer tear. Weld shrinkage-induced local strain reaches the yield point strain often several times larger than the strain caused by the load;
2 the residual stress caused by uneven cooling. Residual stresses in the absence of external force equilibrium of internal stress from a variety of hot-rolled steel has a cross-section of such residual stress, generally the larger beam cross-sectional size, the greater the residual stresses. Although the residual stress is self-equilibrium, but the steel members under loads or have a certain impact on the performance. Such as deformation, stability, fatigue, etc. are likely to produce adverse effects.
3 hot-rolled steel products, thickness and edge width for poor control in this regard. We are familiar with thermal expansion and contraction, since the beginning of the hot rolled out even the length, thickness are achieved and finally cooled or there will be some negative difference, this negative difference edge width is wider, thicker the performance of the more obvious. So for large steel, for steel edge width, thickness, length, angle, and no law requires very precise edges.
Benefits:
Large-diameter hot-rolled seamless steel pipe can damage the ingot casting organizations, grain refinement of steel and eliminate defects in the microstructure, so that the dense tissue steel, mechanical properties are improved. This improvement is mainly reflected in the rolling direction, so that the steel is no longer certain extent isotropic; pouring bubbles formed cracks and porosity, but also in under the action of high temperature and pressure welding.
Disadvantages:
1 After hot rolling, the steel inside the non-metallic inclusions (mainly sulfides and oxides, and silicates) is pressed into the sheet, delamination (interlayer) phenomenon. Layered in the thickness direction of the steel in tension performance deteriorated significantly, and may occur in the weld shrinkage interlayer tear. Weld shrinkage-induced local strain reaches the yield point strain often several times larger than the strain caused by the load;
2 the residual stress caused by uneven cooling. Residual stresses in the absence of external force equilibrium of internal stress from a variety of hot-rolled steel has a cross-section of such residual stress, generally the larger beam cross-sectional size, the greater the residual stresses. Although the residual stress is self-equilibrium, but the steel members under loads or have a certain impact on the performance. Such as deformation, stability, fatigue, etc. are likely to produce adverse effects.
3 hot-rolled steel products, thickness and edge width for poor control in this regard. We are familiar with thermal expansion and contraction, since the beginning of the hot rolled out even the length, thickness are achieved and finally cooled or there will be some negative difference, this negative difference edge width is wider, thicker the performance of the more obvious. So for large steel, for steel edge width, thickness, length, angle, and no law requires very precise edges.
Hot dip galvanized coil production process as well as in various industry applications
Hot-dip galvanized coil processing will be part of the lubricant remains in the inner and outer surfaces, hot dip galvanized after annealing in the formation of carbon spiral surface in 1980 has experts on the surface of carbon galvanized spiral done a lot of research, the carbon galvanized tube life will be adversely affected. Although the carbon steel pipe service life thereafter on the degree of influence as well as quantitative indicators carbon effect no final conclusions, but harmful carbon film on hot-dip galvanized coil has agreed, in order to eliminate the carbon surface of the tube, skim become hot an essential part of galvanizing process.
Sawing process for producing interrupt cutting die head, cut head and tail and local defects on the finished product. With the use of the product requirements gradually increased, the quality of some products have been speaking out sawing up to 1mm density within it. Slope of the finished cut sawing and cutting burr in the standard has a corresponding provisions should pay attention when cutting. Semi-finished products after sawing, should remain in the wall inside the sawdust to clean up.
Factors affecting the quality of hot-dip galvanizing: Operating speed: When immersed steel workpiece and personnel should ensure that the premise of safety as fast as possible, this will ensure that each part of the whole galvanized thickness of the film are the same, according to the steel lifting speed structure, material, and the use of different lengths at different speeds, in general lifting speed of 1.5 m / min can ensure better surface brightness and zinc reflux.
Tooling used: hot dip galvanized tooling for galvanizing process is very important, a good tooling can greatly improve the yield and quality, but the tooling design depends on the type of galvanized and therefore require site design, tooling design should take into account the production capacity, steel shapes, sizes and technical requirements of customers.
Cooling passivation: hot dip galvanized steel in the sink after doing the cooling process, the cooling water is usually tap water, steel zinc pot from hanging out as soon as possible after cooling, the workpiece can be maintained without distortion. Optimum temperature should be between 30 ° -70 °, can be added to the water amount of surface active agent, to improve the surface gloss of steel.
Renovation Inspection: good-plated parts in accordance with the requirements and standards (national standard GB / T 13912-2002) for thickness and appearance inspection, will be attached to the surface plating zinc ash, zinc dross and other polishing, hot dip galvanized coil meet the requirements to cross the detection plant.
Sawing process for producing interrupt cutting die head, cut head and tail and local defects on the finished product. With the use of the product requirements gradually increased, the quality of some products have been speaking out sawing up to 1mm density within it. Slope of the finished cut sawing and cutting burr in the standard has a corresponding provisions should pay attention when cutting. Semi-finished products after sawing, should remain in the wall inside the sawdust to clean up.
Factors affecting the quality of hot-dip galvanizing: Operating speed: When immersed steel workpiece and personnel should ensure that the premise of safety as fast as possible, this will ensure that each part of the whole galvanized thickness of the film are the same, according to the steel lifting speed structure, material, and the use of different lengths at different speeds, in general lifting speed of 1.5 m / min can ensure better surface brightness and zinc reflux.
Tooling used: hot dip galvanized tooling for galvanizing process is very important, a good tooling can greatly improve the yield and quality, but the tooling design depends on the type of galvanized and therefore require site design, tooling design should take into account the production capacity, steel shapes, sizes and technical requirements of customers.
Cooling passivation: hot dip galvanized steel in the sink after doing the cooling process, the cooling water is usually tap water, steel zinc pot from hanging out as soon as possible after cooling, the workpiece can be maintained without distortion. Optimum temperature should be between 30 ° -70 °, can be added to the water amount of surface active agent, to improve the surface gloss of steel.
Renovation Inspection: good-plated parts in accordance with the requirements and standards (national standard GB / T 13912-2002) for thickness and appearance inspection, will be attached to the surface plating zinc ash, zinc dross and other polishing, hot dip galvanized coil meet the requirements to cross the detection plant.
How to control the quality of spiral steel in production
The spiral pipe production process to control the quality of it is very important to the blank material abnormal perforations vary based on the temperature difference. Thermal expansion pipe but mostly in about 1200 ℃, carbon and other alloying elements to be slightly lower when the temperature is higher. Heating operation is the second key is to try to cut the number of oxide. Especially in hot kneading elbow, spiral steel pipe from stuff life expectancy and kneading surface quality of pipe left, pleading even more severe.
The spiral pipe production process, because the primary processing is carried out in a hot state, the heating operation is very important for the resolution process of the quality of products. Such as heat with the stove, according to their effect, divided into two kinds of furnaces and reheating; former for the fabric is heated from room temperature to the processing temperature; which is used during the processing of billets reheated to the required processing temperature. Heating wrong will become perhaps the inner surface of the tube outer surface showing cracks, folds and migraine pain and other scrap the reason. There are many ways the furnace, but the primary use of the annular furnace. This has an annular hearth furnace, which can slowly shift along the bottom of the blank from the entrance into the radial direction, reverse one can be used at the outlet of the heating and soaking temperature to the rules one kind of stove. This heating operation is the key to uniformly heat the billet to a temperature suitable for processing. Since a great impact on the quality piercing, that is, perforation processing temperatures are important condition affecting the quality, it is generally to processing of piercing the billet temperature control.
The spiral pipe production process, because the primary processing is carried out in a hot state, the heating operation is very important for the resolution process of the quality of products. Such as heat with the stove, according to their effect, divided into two kinds of furnaces and reheating; former for the fabric is heated from room temperature to the processing temperature; which is used during the processing of billets reheated to the required processing temperature. Heating wrong will become perhaps the inner surface of the tube outer surface showing cracks, folds and migraine pain and other scrap the reason. There are many ways the furnace, but the primary use of the annular furnace. This has an annular hearth furnace, which can slowly shift along the bottom of the blank from the entrance into the radial direction, reverse one can be used at the outlet of the heating and soaking temperature to the rules one kind of stove. This heating operation is the key to uniformly heat the billet to a temperature suitable for processing. Since a great impact on the quality piercing, that is, perforation processing temperatures are important condition affecting the quality, it is generally to processing of piercing the billet temperature control.
Spiral piling welded pipe plasma cutting
As hot-rolled coil of material performance and production technical process, the domestic manufacturers meet the standard of the manufacturer, which is less than the steel manufacturers, on the other hand their production processes and quality level of its market price is also higher than the heat rolled steel plate. This is spiral piling pipe market price higher than the Longitudinal main reason. For the composition of steel selling prices, material prices is the dominant or even the decisive factor.
Longitudinal spiral welded pipe and carefully examine the price difference, spiral welded pipe Longitudinal slightly higher price is due to production of the main material of the price difference. However, steel production, only the project of a part, if taking into account the overall project quality, project cost and other factors, spiral welded pipe still has the overall advantage.
Production cut length tube length than the usual rate of finished pipe larger decline, production companies proposed fare increase is reasonable. The rate of increase of the enterprise are not consistent, the base price is generally based on the increase of about 10%. Usual length length length should be within the scope of the requirements of the contract is a fixed length dimension. But the actual operation is definitely cut out cut lengths is unlikely, so the standard cut length requirements for the allowable positive deviation values. If the standard deviation is no double length and cutting margin requirement, by agreement between the manufacturer and indicated in the contract. Times as long as the length scale of the same length, will give producers to bring a significant reduction in finished product rate, so manufacturers proposed fare increase is justified, the increase in the rate of price increases with the length of the same length.
Plasma cutting workpiece process will produce a large number of metal vapor, ozone, nitrogen oxides, soot, will seriously pollute the surrounding environment. The key to solve the problem is how to smoke the entire plasma dust sucked into the dust removal equipment, thus preventing air pollution. For spiral welded pipe plasma cutting, dust difficulty is:
1, the plasma gun nozzle cutting the air blown simultaneously to two opposite directions, so that the smoke coming out from both ends of the spiral pipe, spiral pipe is mounted on the suction port in one direction is very difficult to recycle dust .
2, the external cold air inlet gap from outside into the suction machine and a large amount of wind, so that the spiral steel pipe smoke and dust inhalation of cold air is greater than the total amount of the effective air volume, thus cutting soot absorption becomes completely impossible.
3, due to the cutting area far from the dust intake to reach the entrance of the wind sucked hard twitching soot.
Longitudinal spiral welded pipe and carefully examine the price difference, spiral welded pipe Longitudinal slightly higher price is due to production of the main material of the price difference. However, steel production, only the project of a part, if taking into account the overall project quality, project cost and other factors, spiral welded pipe still has the overall advantage.
Production cut length tube length than the usual rate of finished pipe larger decline, production companies proposed fare increase is reasonable. The rate of increase of the enterprise are not consistent, the base price is generally based on the increase of about 10%. Usual length length length should be within the scope of the requirements of the contract is a fixed length dimension. But the actual operation is definitely cut out cut lengths is unlikely, so the standard cut length requirements for the allowable positive deviation values. If the standard deviation is no double length and cutting margin requirement, by agreement between the manufacturer and indicated in the contract. Times as long as the length scale of the same length, will give producers to bring a significant reduction in finished product rate, so manufacturers proposed fare increase is justified, the increase in the rate of price increases with the length of the same length.
Plasma cutting workpiece process will produce a large number of metal vapor, ozone, nitrogen oxides, soot, will seriously pollute the surrounding environment. The key to solve the problem is how to smoke the entire plasma dust sucked into the dust removal equipment, thus preventing air pollution. For spiral welded pipe plasma cutting, dust difficulty is:
1, the plasma gun nozzle cutting the air blown simultaneously to two opposite directions, so that the smoke coming out from both ends of the spiral pipe, spiral pipe is mounted on the suction port in one direction is very difficult to recycle dust .
2, the external cold air inlet gap from outside into the suction machine and a large amount of wind, so that the spiral steel pipe smoke and dust inhalation of cold air is greater than the total amount of the effective air volume, thus cutting soot absorption becomes completely impossible.
3, due to the cutting area far from the dust intake to reach the entrance of the wind sucked hard twitching soot.
Wednesday, June 19, 2013
Spiral pipe forming methods and causes internal stress
Spiral welded steel tube in the petrochemical, heat pipe network and urban water supply and drainage engineering and other fields have a wide range of applications, especially in the long-distance transportation of oil pipeline and natural gas pipelines and construction piling is more widely used. Oil, gas pipe spiral welded steel pipe almost all, in addition, used in building piling pipe well. With high security, durability and economic rationality. Since the diameter of the spiral welded steel sheet width generally not limited, by a variety of different specifications of the plate width coil manufacture, so no wide plate width of the plate. This gives plate manufacturing, transportation convenience, the use of flat steel strip ratio much lower price, suitable for China's actual situation. Spiral welded steel pipe there is a problem produce elastic recovery after welding steel pipe, steel pipe previously exposed to the equivalent one circumferential tensile stress, the stress will produce stress corrosion and reduced ability of the pressure tube.
Spiral welded steel pipe using a continuous forming, welding fabrication method, is now widely used within and outside deck holds two kinds of molding method.
And the inner forming roll carrier roller (or external brake rollers) is composed of a molded plate along the direction shown by the arrows into the forming device, while forming the side weld. Molding can be obtained by adjusting the different sizes of the pipe. In order to prevent excessive bending, forming rolls three points of contact with the plate height is generally not much difference, manufacturers have adopted an insufficient amount molding, pipe made within the radius of curvature is to rely on roll (or external hold rolls) formed by the radius of curvature that in within each roll (or external hold rolls) in the elastic and plastic plates are actually mixed deformation. Spiral welded steel pipe cut open along the generatrix direction, there must be a certain amount of circumferential openings, namely the existence of certain steel pipe bomb complex quantity, steel residual stress exists. Since the existence of internal stress, steel external tensile stress, so this will reduce the ability of the pressure tube, increasing the external pipe corrosion, to adversely affect the use of steel.
Spiral welded steel pipe using a continuous forming, welding fabrication method, is now widely used within and outside deck holds two kinds of molding method.
And the inner forming roll carrier roller (or external brake rollers) is composed of a molded plate along the direction shown by the arrows into the forming device, while forming the side weld. Molding can be obtained by adjusting the different sizes of the pipe. In order to prevent excessive bending, forming rolls three points of contact with the plate height is generally not much difference, manufacturers have adopted an insufficient amount molding, pipe made within the radius of curvature is to rely on roll (or external hold rolls) formed by the radius of curvature that in within each roll (or external hold rolls) in the elastic and plastic plates are actually mixed deformation. Spiral welded steel pipe cut open along the generatrix direction, there must be a certain amount of circumferential openings, namely the existence of certain steel pipe bomb complex quantity, steel residual stress exists. Since the existence of internal stress, steel external tensile stress, so this will reduce the ability of the pressure tube, increasing the external pipe corrosion, to adversely affect the use of steel.
The main large diameter welded pipe production methods
For transporting and piling of large diameter pipe, manufactured using various welding methods, such as using electric arc welding under flux layer, the contact resistance welding, flash welding and other welding and high frequency currents. Press the seam can be divided into straight seam welded and spiral welded two ways, straight seam welding production process is composed of the following main steps: forming tube within the model to make double-sided welding, welded steel tube imposed on small expanding.
The method currently used is the most complete with a huge three-step molding production press with die no longitudinal joints 12 meters long pipe, and the shape and size are very accurate. The oil pipeline is the most common method used solvent layer under the double seam welding speeds of up to 140 ^ -150 m / hour. Soldering should be repaired weld, then cut the head and pipe sizing. The modern sizing method is applied to the inner pipe hydraulic diameter to the expansion diameter of 1.5-2.5% pots, fixed length to diameter, on the other hand to improve the yield limit of about 20%.
Nickel is an excellent corrosion-resistant materials, is an important alloying element in steel. Nickel is the formation of austenite in the steel elements, but to obtain pure carbon-nickel austenitic steels, nickel volume to reach 24%; whereas only 27% of nickel when the steel corrosion in certain media Corrosion can significantly changed. So Nickel alone can not constitute a stainless steel. However, both nickel and chromium present in the stainless steel, the nickel-containing stainless steel, but has many valuable properties.
Based on the above case shows, nickel as an alloying element in stainless steel effect, is that it enables high-chromium steel tissue changes, so that the corrosion resistance of stainless steel and obtain certain improved process performance.
The method currently used is the most complete with a huge three-step molding production press with die no longitudinal joints 12 meters long pipe, and the shape and size are very accurate. The oil pipeline is the most common method used solvent layer under the double seam welding speeds of up to 140 ^ -150 m / hour. Soldering should be repaired weld, then cut the head and pipe sizing. The modern sizing method is applied to the inner pipe hydraulic diameter to the expansion diameter of 1.5-2.5% pots, fixed length to diameter, on the other hand to improve the yield limit of about 20%.
Nickel is an excellent corrosion-resistant materials, is an important alloying element in steel. Nickel is the formation of austenite in the steel elements, but to obtain pure carbon-nickel austenitic steels, nickel volume to reach 24%; whereas only 27% of nickel when the steel corrosion in certain media Corrosion can significantly changed. So Nickel alone can not constitute a stainless steel. However, both nickel and chromium present in the stainless steel, the nickel-containing stainless steel, but has many valuable properties.
Based on the above case shows, nickel as an alloying element in stainless steel effect, is that it enables high-chromium steel tissue changes, so that the corrosion resistance of stainless steel and obtain certain improved process performance.
Seamless common pitfalls magnetic particle testing or penetrant testing
Magnetic particle testing or penetrant testing can effectively find surface cracks, folds, double skin, hairline, pinholes and other surface defects. For ferromagnetic materials, magnetic particle inspection method should be preferred, because of its high detection sensitivity; For non-ferromagnetic material, such as stainless steel seamless pipe, then a penetration assay.
Reserved resection margin when both ends is small, causes the detection apparatus, both ends of the head may not be effectively detected, and ends there is most likely the site of cracks or other defects. If there is a potential end tendency to crack, the installation of the weld heat affected also possible to make the potential crack. Therefore, it should be noted that certain areas of the welded steel tube detection, to detect defects in steel tip extensions. Use the online austenitic seamless insulation is damaged or when rain may have infiltrated the site, should pay attention to the infiltration testing to find stress corrosion cracking or pitting corrosion and other defects. However, magnetic particle or penetrant testing can only detect the outer surface of the steel pipe, internal and surface defects are powerless. Inner surface of the test, especially crack class defect detection through ultrasonic testing must be carried out.
Reserved resection margin when both ends is small, causes the detection apparatus, both ends of the head may not be effectively detected, and ends there is most likely the site of cracks or other defects. If there is a potential end tendency to crack, the installation of the weld heat affected also possible to make the potential crack. Therefore, it should be noted that certain areas of the welded steel tube detection, to detect defects in steel tip extensions. Use the online austenitic seamless insulation is damaged or when rain may have infiltrated the site, should pay attention to the infiltration testing to find stress corrosion cracking or pitting corrosion and other defects. However, magnetic particle or penetrant testing can only detect the outer surface of the steel pipe, internal and surface defects are powerless. Inner surface of the test, especially crack class defect detection through ultrasonic testing must be carried out.
LSAW pipe flaring after water washing device design applications
In the process of spiral piling pipe production, internal and external surfaces of the steel pipe after expanding oil and emulsion will exist, if cleaning not clean will caused serious influence internal and external anti-corrosion of steel pipeThus, by expanding the diameter to the water after washing device for cleaning inner and outer surfaces of the steel pipe, steel pipe external corrosion to meet the process requirements. Nanjing Dragon LSAW steel pipe company production line of water flushing device used in the design of the steel inputs, outputs and internal roller flush lever is tilted 1 ° approach and flush the whole head made of stainless steel, professional cleaning nozzle using MEG nozzle, the entire flushing device used for washing room fully enclosed protection. The device has been installed with favorable results.
Water flushing device profile flared water after washing device, mainly by the steel input and output roller, and flush, external washing, water systems, washing room and other components. Rinse water pipe flushing device features basic parameters: pipe diameter 508 ~ 1 422 mm; Pipe length 8 000 ~ 12 500 mm. After expanding since the beginning of washing and rinsing outside rinse. Use only the outer rinse water, and flush with emulsion and water. Outside by an electrically controlled pneumatic flush valves for water control, and flush consists of two electrically controlled pneumatic valve and water emulsion, respectively controls the operation. In this process, the end of the intake pipe brought out. Steel roller by a separate access (position consists of sensors, switch control), open the pneumatic valve for flushing the inner steel pipe emulsion washing, pipe marching in place to stop.
Water flushing device profile flared water after washing device, mainly by the steel input and output roller, and flush, external washing, water systems, washing room and other components. Rinse water pipe flushing device features basic parameters: pipe diameter 508 ~ 1 422 mm; Pipe length 8 000 ~ 12 500 mm. After expanding since the beginning of washing and rinsing outside rinse. Use only the outer rinse water, and flush with emulsion and water. Outside by an electrically controlled pneumatic flush valves for water control, and flush consists of two electrically controlled pneumatic valve and water emulsion, respectively controls the operation. In this process, the end of the intake pipe brought out. Steel roller by a separate access (position consists of sensors, switch control), open the pneumatic valve for flushing the inner steel pipe emulsion washing, pipe marching in place to stop.
Thick-walled stainless steel pipe piling pipe surface treatment process problems and solutions
Thick wall stainless steel piling pipe surface treatment processing problems in the process of weld defect is more serious, using manual mechanical polishing treatment methods to compensate, resulting in grinding marks, resulting in uneven surface and affect appearance. Inconsistent surface passivation pickling welds only, but also caused uneven surface and affect appearance. Pickling and passivation is difficult to remove scratches whole, nor can a variety generated during processing to remove scratches, and can not remove the scratches, welding spatter adhering to the surface of stainless steel and carbon steel, splash and other impurities, resulting in a in the presence of corrosive media, chemical etching or electrochemical corrosion and rust. Polishing uneven hand polished after passivation pickling passivation treatment on larger workpieces, it is difficult to achieve uniform treatment effect, which can not be satisfactory uniform surface. And work expenses, materials costs are also higher. Limited capacity pickling pickling and passivation paste is not a panacea for plasma cutting, flame cutting and productivity and black oxide, more difficult to remove. Scratches caused by human factors more serious in the lifting, transportation and construction process, bump, drag, hammering scratches caused by human factors such as more serious, making the surface more difficult, but also the main reason for rust treatment. Equipment factors profiles, sheet roll bending, bending process, causing scratches and creases are also the main reason for rust treatment. Thick-walled stainless steel piling pipe raw materials procurement, storage process, due to lifting and transportation process produces more serious bump and scratches, but also one of the causes rust.
Thick-walled stainless steel piling pipe surface treatment should take precautionary measures, which should be special thick-walled stainless steel tube storage storage racks, storage racks should be wood or steel frame or painted surface mat with rubber pads to carbon steel and other metal material isolation. Storage, storage location should be easy lifting, and other materials storage area is relatively isolated, should protective measures to avoid dust, oil, rust on stainless steel contamination. Thick-walled stainless steel pipe lifting should use a dedicated spreader, such as lifting belts, special chucks, etc., prohibited the use of rope to avoid scratching the surface; and in the lifting and placement should be avoided shock bump caused by scratches. Thick-walled stainless steel pipe transport, the application of means of transport (such as car, car batteries, etc.), and shall be clean with isolation precautions to prevent dust, oil, rust contamination of stainless steel. Prohibited drag, avoid the bump, scratch. Thick-walled stainless steel tube cleaning polished surface treatment, if any damage should be polished, especially caused by contact with carbon steel scratch and splash, the damage caused by cutting slag must be carefully and thoroughly cleaned polished clean. Mechanical polishing using an appropriate polishing tool for polishing, request processing uniform, and to avoid over-polishing and re-scratches. Dust stainless steel parts during degreasing pickling passivation, you must remove the oil by technology, scale, dirt and other debris. Water sandblasting according to different processing requirements, use of different micro-glass beads, different process parameters, and to avoid overspray and so on. Pickling and passivation of stainless steel parts must be in strict accordance with pickling passivation passivation process requirements. After cleaning and drying pickling passivation should be in strict accordance with technical and, rinse and dry thoroughly to remove residual acid. Protected stainless steel surface treatment has been completed, should be prepared to protect and avoid touching and oil, dust and other debris secondary pollution. Prevent further processing of stainless steel surface treatment has been completed, the parts or products should be avoided reprocessed.
Thick-walled stainless steel piling pipe surface treatment should take precautionary measures, which should be special thick-walled stainless steel tube storage storage racks, storage racks should be wood or steel frame or painted surface mat with rubber pads to carbon steel and other metal material isolation. Storage, storage location should be easy lifting, and other materials storage area is relatively isolated, should protective measures to avoid dust, oil, rust on stainless steel contamination. Thick-walled stainless steel pipe lifting should use a dedicated spreader, such as lifting belts, special chucks, etc., prohibited the use of rope to avoid scratching the surface; and in the lifting and placement should be avoided shock bump caused by scratches. Thick-walled stainless steel pipe transport, the application of means of transport (such as car, car batteries, etc.), and shall be clean with isolation precautions to prevent dust, oil, rust contamination of stainless steel. Prohibited drag, avoid the bump, scratch. Thick-walled stainless steel tube cleaning polished surface treatment, if any damage should be polished, especially caused by contact with carbon steel scratch and splash, the damage caused by cutting slag must be carefully and thoroughly cleaned polished clean. Mechanical polishing using an appropriate polishing tool for polishing, request processing uniform, and to avoid over-polishing and re-scratches. Dust stainless steel parts during degreasing pickling passivation, you must remove the oil by technology, scale, dirt and other debris. Water sandblasting according to different processing requirements, use of different micro-glass beads, different process parameters, and to avoid overspray and so on. Pickling and passivation of stainless steel parts must be in strict accordance with pickling passivation passivation process requirements. After cleaning and drying pickling passivation should be in strict accordance with technical and, rinse and dry thoroughly to remove residual acid. Protected stainless steel surface treatment has been completed, should be prepared to protect and avoid touching and oil, dust and other debris secondary pollution. Prevent further processing of stainless steel surface treatment has been completed, the parts or products should be avoided reprocessed.
Tuesday, June 18, 2013
Application of coal tar epoxy in anti-corrosion pipe insulation technology
With the current domestic pipeline corrosion technology Calvary industry needs, a variety of high-performance anti-corrosion insulation technology developed which is more excellent anti-corrosion pipe insulation, such as polyethylene anti-corrosion steel, coal tar epoxy steel, epoxy powder anti-corrosion steel pipe.
Anti-corrosion pipe insulation coal tar epoxy anti corrosive steel pipe, using coal tar epoxy anti corrosive coating composition consists of two components, epoxy and coal tar. Belonging to two-component coating, which features strong adhesion, toughness, resistance to moisture, water, chemical resistance, and prevent all kinds of ions through the film's performance, while coal tar epoxy coated objects have the same common expansion and contraction characteristics, making epoxy coal tar coating does not appear because the pipe expansion or contraction caused by falling, cracking phenomenon.
Coal tar epoxy anti corrosive coating as high cost, and through engineering tests show that can be used safely for twenty years. Coal tar epoxy pipe Environment: seawater or freshwater pipe wall corrosion, underground pipeline wall corrosion, heat pipe wall, sluice anti corrosive paint and other fields have better results.
Anti-corrosion pipe insulation coal tar epoxy anti corrosive steel pipe, using coal tar epoxy anti corrosive coating composition consists of two components, epoxy and coal tar. Belonging to two-component coating, which features strong adhesion, toughness, resistance to moisture, water, chemical resistance, and prevent all kinds of ions through the film's performance, while coal tar epoxy coated objects have the same common expansion and contraction characteristics, making epoxy coal tar coating does not appear because the pipe expansion or contraction caused by falling, cracking phenomenon.
Coal tar epoxy anti corrosive coating as high cost, and through engineering tests show that can be used safely for twenty years. Coal tar epoxy pipe Environment: seawater or freshwater pipe wall corrosion, underground pipeline wall corrosion, heat pipe wall, sluice anti corrosive paint and other fields have better results.
Precision light pipe main characteristics and uses
Precision light pipe main features:
Steel outer wall precision, high-quality finish, heat-treated steel no oxide layer, the inner wall high cleanliness steel to withstand high pressure, cold deformation, flaring, flattening without cracks, steel color: white with bright, with high metal luster.
Precision light pipe usage:
Automotive, machinery parts and other precision steel pipe, finish with high mechanical requirements. And now the precision steel users not only on the accuracy, finish requirements are relatively high users, and due to high accuracy precision bright tubes, tolerances can be maintained at 2 - 8 wire, so a lot of machining users in order to save labor, materials, time loss, the seamless pipe or round bar is slowly transformed into precision light pipe. Precision seamless bright is a fine drawing or cold rolling through after a high-precision steel pipe material. Because precision light pipe outer wall oxide layer to withstand high pressure without leakage, high-precision, high-quality finish, cold deformation, flaring, flattening without cracks, etc., can be used for a variety of complex deformation and mechanical processing. Steel color: white with bright, with high metallic luster.
Precision light pipe chemical composition of carbon C, Si Si, manganese Mn, S, P P, chromium Cr. Precision light pipe technology Description: high quality carbon steel, finishing, no oxidation bright heat treatment (NBK status), nondestructive testing, pipe wall dedicated scrub and after high pressure washing equipment, anti-rust oil for rust on steel processing, both ends of the cover for dust treatment.
Precision light pipe main purposes: mainly used for the production of pneumatic or hydraulic components products, such as cylinder or cylinders, which can be seamless, there are also welded steel tube. Automotive, machinery and other accessories used for precision steel pipe, finish with high mechanical requirements. And now the precision steel users not only on the accuracy, finish high demand of users, because of precision seamless bright, high precision, tolerance can be maintained at 2 - 8 wire, so a lot of machining users in order to save labor, materials, time loss, or the seamless round is slowly transformed into precision seamless bright.
Steel outer wall precision, high-quality finish, heat-treated steel no oxide layer, the inner wall high cleanliness steel to withstand high pressure, cold deformation, flaring, flattening without cracks, steel color: white with bright, with high metal luster.
Precision light pipe usage:
Automotive, machinery parts and other precision steel pipe, finish with high mechanical requirements. And now the precision steel users not only on the accuracy, finish requirements are relatively high users, and due to high accuracy precision bright tubes, tolerances can be maintained at 2 - 8 wire, so a lot of machining users in order to save labor, materials, time loss, the seamless pipe or round bar is slowly transformed into precision light pipe. Precision seamless bright is a fine drawing or cold rolling through after a high-precision steel pipe material. Because precision light pipe outer wall oxide layer to withstand high pressure without leakage, high-precision, high-quality finish, cold deformation, flaring, flattening without cracks, etc., can be used for a variety of complex deformation and mechanical processing. Steel color: white with bright, with high metallic luster.
Precision light pipe chemical composition of carbon C, Si Si, manganese Mn, S, P P, chromium Cr. Precision light pipe technology Description: high quality carbon steel, finishing, no oxidation bright heat treatment (NBK status), nondestructive testing, pipe wall dedicated scrub and after high pressure washing equipment, anti-rust oil for rust on steel processing, both ends of the cover for dust treatment.
Precision light pipe main purposes: mainly used for the production of pneumatic or hydraulic components products, such as cylinder or cylinders, which can be seamless, there are also welded steel tube. Automotive, machinery and other accessories used for precision steel pipe, finish with high mechanical requirements. And now the precision steel users not only on the accuracy, finish high demand of users, because of precision seamless bright, high precision, tolerance can be maintained at 2 - 8 wire, so a lot of machining users in order to save labor, materials, time loss, or the seamless round is slowly transformed into precision seamless bright.
Large-diameter welded pipe production principle and purpose
Generally by high-frequency straight seam welded pipe unit will be certain specifications elongated strip and rolled into a circular tube straight seam welded steel pipe. The large-diameter welded pipe is over 1000 mm diameter straight seam steel pipe, straight seam steel pipe on the market today can reach the largest diameter 2250 mm, large-diameter straight seam double submerged arc welded steel pipe production process mainly based products by bending , commissure, internal welding, outside welding, straightening, flat top channel processes. Is a large pipeline projects, water gas engineering, construction.
The best choice for this type of use of national natural gas pipe up to 20 million tons, most of the foreign imports, competition in the market is small, demand, market prospects broad.
The shape of the straight pipe joints may be circular, square or may be profiled, depending on the sizing after welding. Large-diameter straight seam steel pipe welds with large-diameter pipe is parallel to the longitudinal steel pipe. Usually divided into metric welded steel tube, welded thin-walled tube, transformer cooling pipes and so on.
Longitudinal production process is simple, high efficiency, low cost, rapid development. Mainly used in water engineering, petrochemical industry, chemical industry, power industry, agricultural irrigation, urban construction. For the transport of liquids: water supply and drainage. For gas transportation: gas, steam, liquefied petroleum gas. For structural purposes: as piling pipe for bridges; docks, roads, buildings and other structures tube.
The best choice for this type of use of national natural gas pipe up to 20 million tons, most of the foreign imports, competition in the market is small, demand, market prospects broad.
The shape of the straight pipe joints may be circular, square or may be profiled, depending on the sizing after welding. Large-diameter straight seam steel pipe welds with large-diameter pipe is parallel to the longitudinal steel pipe. Usually divided into metric welded steel tube, welded thin-walled tube, transformer cooling pipes and so on.
Longitudinal production process is simple, high efficiency, low cost, rapid development. Mainly used in water engineering, petrochemical industry, chemical industry, power industry, agricultural irrigation, urban construction. For the transport of liquids: water supply and drainage. For gas transportation: gas, steam, liquefied petroleum gas. For structural purposes: as piling pipe for bridges; docks, roads, buildings and other structures tube.
Thursday, June 13, 2013
How to obtain seamless steel tube
Hot-rolled seamless pipe mill in general on automatically produced. Solid tube inspection and removal of surface defects, cut into desired length, end to end in the perforated tube surface-centering, and then sent to the furnace heating, punch a hole. In the hole while continuing to rotate and move forward in the roll and the role of the head, gradually formed within the tube cavity, called the capillary. And then sent to the automatic rolling machine rolling inheritance. Finally after all the whole entire wall thickness are, after sizing mill sizing, to specifications. Use of continuous production of hot-rolled seamless steel pipe mill is older than the raise method.
If you wish to get smaller and better quality seamless steel tube, must be cold-rolled, drawn or a combination of methods. Usually in the two-roll cold rolling mill for long, pipe hole in the variable section tapered slot and does not move the head of the circular hole formed in the rolling. Drawing is usually 0.5 ~ 100T single chain or double chain drawing captain proceed.
Heating tube extrusion method is about good squeeze on the closed cylinder, perforated extruded rod rod and move together, so that extrusion from the smaller hole in the extrusion die. This method can produce a smaller diameter pipe.
If you wish to get smaller and better quality seamless steel tube, must be cold-rolled, drawn or a combination of methods. Usually in the two-roll cold rolling mill for long, pipe hole in the variable section tapered slot and does not move the head of the circular hole formed in the rolling. Drawing is usually 0.5 ~ 100T single chain or double chain drawing captain proceed.
Heating tube extrusion method is about good squeeze on the closed cylinder, perforated extruded rod rod and move together, so that extrusion from the smaller hole in the extrusion die. This method can produce a smaller diameter pipe.
Large diameter spiral pipe pressure test machine works
Large diameter spiral steel pipe carrying water conservancy in the application of the time to be hydrostatically tested to ensure the quality of spiral piling pipe, usually when the test is to be tested with the test machine. Then the pressure test machine works, what is it? Here everyone to know about it!
Large diameter spiral piling pipe hydrostatic testing machine works:
Large diameter spiral piling pipe hydrostatic testing machine during the pressure test, the first sealing device right through the end of the test tube is sealed at both ends and low-pressure water injection, water injection process through the exhaust valve exhaust air in the tube, filled with water at low pressure through the booster device to the high-pressure water injection tube until the required test pressure booster.
After reaching the required test pressure holding pressure at the stipulated time, if large diameter spiral pipe in the pressure test without leakage, deformation phenomena, proceed relief. Then open end seals, low-pressure water discharge will be sent to test large diameter spiral pipe for visual inspection station to check for suspicious penetration. Pressure test according to the standard required for the pressure curve during automatic recording device records.
Large diameter spiral piling pipe hydrostatic testing machine works:
Large diameter spiral piling pipe hydrostatic testing machine during the pressure test, the first sealing device right through the end of the test tube is sealed at both ends and low-pressure water injection, water injection process through the exhaust valve exhaust air in the tube, filled with water at low pressure through the booster device to the high-pressure water injection tube until the required test pressure booster.
After reaching the required test pressure holding pressure at the stipulated time, if large diameter spiral pipe in the pressure test without leakage, deformation phenomena, proceed relief. Then open end seals, low-pressure water discharge will be sent to test large diameter spiral pipe for visual inspection station to check for suspicious penetration. Pressure test according to the standard required for the pressure curve during automatic recording device records.
The maintenance method of steel pipe
With China's sustained economic development, the state vigorously develop the energy sector, long-distance oil pipeline and gas pipeline are an important way to energy security in the oil and gas pipeline anti-corrosion construction process, the steel pipe anti-corrosion surface treatment is to determine the key factors of life First, it is the anti-corrosion layer and the tube can firmly with the premise. Verified by research institutions, in addition to the life of the coating depends on the type of coating, coating quality and construction environment and other factors, the steel surface treatment on the life of the coating of about 50%, therefore, should be strictly in accordance with the anti-corrosion layer specification steel surface, continually explore and summarize, and constantly improve steel surface treatment method.
1, the pipe by solvent cleaning, emulsion cleaning the steel surface, in order to achieve the removal of oil, grease, dust, lubricants and similar organic matter, but it can not remove the steel surface rust, oxide, flux, etc., so the production of anti-corrosion only as an adjunct.
2, the main use of tools rust steel wire brushes and other tools for steel surface sanding, you can remove loose or warped oxide, rust, welding slag. Hand tools rust can reach Sa2 grade power tools rust Sa3 level can be achieved, if the steel surface firmly attached to the iron skin, the effect is not ideal tools rust, anti-corrosion construction required to reach the depth of anchor pattern.
3, steel pickling generally use two methods to do chemical and electrolytic pickling treatment, pipeline corrosion using only chemical pickling can descaling, rust, old paint, sometimes used as a sand blasting after reprocessing . Although chemical cleaning can achieve a certain surface cleanliness and roughness, but the anchor pattern shallow, and easy on the environment caused by pollution.
1, the pipe by solvent cleaning, emulsion cleaning the steel surface, in order to achieve the removal of oil, grease, dust, lubricants and similar organic matter, but it can not remove the steel surface rust, oxide, flux, etc., so the production of anti-corrosion only as an adjunct.
2, the main use of tools rust steel wire brushes and other tools for steel surface sanding, you can remove loose or warped oxide, rust, welding slag. Hand tools rust can reach Sa2 grade power tools rust Sa3 level can be achieved, if the steel surface firmly attached to the iron skin, the effect is not ideal tools rust, anti-corrosion construction required to reach the depth of anchor pattern.
3, steel pickling generally use two methods to do chemical and electrolytic pickling treatment, pipeline corrosion using only chemical pickling can descaling, rust, old paint, sometimes used as a sand blasting after reprocessing . Although chemical cleaning can achieve a certain surface cleanliness and roughness, but the anchor pattern shallow, and easy on the environment caused by pollution.
Sunday, June 9, 2013
Spiral Pipe developments and trends
Spiral steel pipe manufacturing, chemical industry, construction and oil and gas electricity required for important national key project materials, especially oil thermal power construction and other industries as supporting GB spiral pipe market direct power. GB is a measure of a country can become an important symbol of steel power, is a country's comprehensive competitiveness reflected. Spiral steel pipe as one of important new material, has been listed as a national focus on the development of strategic new industries. Spiral steel pipe industry as a traditional branch, early development of spiral steel pipe is mainly to meet the required heat and oil industry, the core material, and highly professional, but the quantity demand is small, difficult to scale production resulting in low business efficiency features. However, with the upgrading of industrial structure, the downstream equipment manufacturing base material requirements for increasingly high value-added products are also increasing, spiral pipe has a broad space for development.
At present China's steel industry competitiveness compared with the international advanced level, there are still some gaps. Main features: First, the low proportion of high-end products can not meet the development needs of the national economy is still dependent on imports; Second, GB spiral steel pipe spiral steel industry and the majority of companies do not establish their own technology innovation system and mechanism, the lack of independent intellectual property rights with technology and product development capabilities. High-end equipment manufacturing, new energy, such as city gas heat pipe with spiral steel industry will be closely related to the future of the highlights spiral pipe market demand, China's equipment manufacturing industry, mainly in the core technology and components controlled by others, the development of spiral steel pipe The key is to occupy the high-end market.
The present situation, the urgent need to break the bottleneck: a, to improve product quality, promote energy conservation, pollution reduction; Second, to improve China's steel industry concentration, eliminate backward production capacity, accelerate the spiral steel pipe industry pace of technological innovation; Third, to accelerate industrial chain construction to form a complete industrial chain of steel. Aviation, and other advanced high-speed rail transportation equipment, blower equipment, metallurgical equipment, electronic equipment and so will be the highlight of the spiral piling pipe market demand, with government support efforts to increase and deepening of reform, China's steel industry will usher in spiral development.
At present China's steel industry competitiveness compared with the international advanced level, there are still some gaps. Main features: First, the low proportion of high-end products can not meet the development needs of the national economy is still dependent on imports; Second, GB spiral steel pipe spiral steel industry and the majority of companies do not establish their own technology innovation system and mechanism, the lack of independent intellectual property rights with technology and product development capabilities. High-end equipment manufacturing, new energy, such as city gas heat pipe with spiral steel industry will be closely related to the future of the highlights spiral pipe market demand, China's equipment manufacturing industry, mainly in the core technology and components controlled by others, the development of spiral steel pipe The key is to occupy the high-end market.
The present situation, the urgent need to break the bottleneck: a, to improve product quality, promote energy conservation, pollution reduction; Second, to improve China's steel industry concentration, eliminate backward production capacity, accelerate the spiral steel pipe industry pace of technological innovation; Third, to accelerate industrial chain construction to form a complete industrial chain of steel. Aviation, and other advanced high-speed rail transportation equipment, blower equipment, metallurgical equipment, electronic equipment and so will be the highlight of the spiral piling pipe market demand, with government support efforts to increase and deepening of reform, China's steel industry will usher in spiral development.
Development advantages of spiral submerged arc welded pipe
Spiral submerged arc welded pipe less investment in equipment, lower prices due to using narrowband (board) volume continuous production of large diameter welded (φ1016mm ~ φ2400mm) pipe, the production process is simple, low cost, low-cost operation has advantages in the medium and large caliber low pressure pipes, heat pipe and piling pipe market has a price advantage, but in the pressure pipeline projects, especially in the application of the gas pipeline should have the necessary hardware configuration, such as non-destructive testing and chemical testing facilities, enhance quality assurance.
Currently, oil and gas in our country has formed a spiral oil pipeline factory dominated system belongs to the basic pattern. Low residual stress and tube end forming machine and other advanced technology to produce flaring, and undergo a rigorous quality control spiral pipe, the quality can be comparable with the Longitudinal, in our natural gas and other long-distance gas pipeline project to get widely used, is the construction of oil and gas pipelines used in the main tube. Its current production capacity has been able to meet our long-distance gas pipeline construction needs, and has been exported. Therefore, we should focus on strengthening the technical transformation of existing units, and strictly control the construction of new capacity.
Currently, oil and gas in our country has formed a spiral oil pipeline factory dominated system belongs to the basic pattern. Low residual stress and tube end forming machine and other advanced technology to produce flaring, and undergo a rigorous quality control spiral pipe, the quality can be comparable with the Longitudinal, in our natural gas and other long-distance gas pipeline project to get widely used, is the construction of oil and gas pipelines used in the main tube. Its current production capacity has been able to meet our long-distance gas pipeline construction needs, and has been exported. Therefore, we should focus on strengthening the technical transformation of existing units, and strictly control the construction of new capacity.
Saturday, June 8, 2013
The development and main manufacturing method of spiral steel pipe
Spiral steel pipe in the proportion in recent years stabilized at 42% to 45%, the pipe on the rise. Spiral steel pipe and welded steel pipe is more variety of materials, reliability and adaptability, especially adapted to thick and steel production. The main problem is high investment, high cost, complex manufacturing process, wall thickness and ovality tolerances. The welded pipe is actually a plate of deep-processed products, the price of similar conditions, spiral steel pipe market competitiveness and improve its reliability, with the continuous improvement of the quality of steel plate and pipe technology and equipment level, part of the spiral steel occupy the market, there is the possibility of welded pipe replaced, but only very limited areas.
Spiral steel hot rolling process is the main manufacturing methods, accounting for 80% of heat production Seamless Pipe Mill production of varieties and quality levels in addition to mill their own skills, but to a large extent constrained by the smelting and casting Therefore advanced smelting process should refer to the complete process management process. International companies are mostly well-known spiral steel pipe factory, or a complete professional steel company, by outsourcing manufacturing spiral for piling( piling pipe) billet is difficult for enterprises in the fierce competition in the market share steady position. Using an electric arc furnace smelting or refining a VD of LF handle a full vacuum casting casting tube round protection of a hot strip mill (NPN, PQF) a process, is the current international advanced spiral pipe production process, using the above process can produce such as OCTG, high-pressure boiler tubes, low-alloy tubes. Tianjin Pipe Corporation, Baosteel Trading (steel) company, Anshan Iron and Steel seamless factory, Baotou seamless factory are to achieve the above process, climbed into steel seamless and Hengyang Steel Tube Company is also supporting projects to build did not pay close attention to the recent realization of the above process can be process. For the smelting equipment, electric arc furnace or converter capacity of not less than 70 a lOOt, create conditions for the ladle refining, full attention should be rolling mill line inspection tools and automatic control system, equipped with advanced detection systems for positioning and high-pressure oil pipe boiler tube production line, should be equipped with a high level of heat treatment and processing systems, the progressive realization of billet hot charging of heat delivery and on-line often, controlled rolling and air cooling and other processes.
Spiral steel hot rolling process is the main manufacturing methods, accounting for 80% of heat production Seamless Pipe Mill production of varieties and quality levels in addition to mill their own skills, but to a large extent constrained by the smelting and casting Therefore advanced smelting process should refer to the complete process management process. International companies are mostly well-known spiral steel pipe factory, or a complete professional steel company, by outsourcing manufacturing spiral for piling( piling pipe) billet is difficult for enterprises in the fierce competition in the market share steady position. Using an electric arc furnace smelting or refining a VD of LF handle a full vacuum casting casting tube round protection of a hot strip mill (NPN, PQF) a process, is the current international advanced spiral pipe production process, using the above process can produce such as OCTG, high-pressure boiler tubes, low-alloy tubes. Tianjin Pipe Corporation, Baosteel Trading (steel) company, Anshan Iron and Steel seamless factory, Baotou seamless factory are to achieve the above process, climbed into steel seamless and Hengyang Steel Tube Company is also supporting projects to build did not pay close attention to the recent realization of the above process can be process. For the smelting equipment, electric arc furnace or converter capacity of not less than 70 a lOOt, create conditions for the ladle refining, full attention should be rolling mill line inspection tools and automatic control system, equipped with advanced detection systems for positioning and high-pressure oil pipe boiler tube production line, should be equipped with a high level of heat treatment and processing systems, the progressive realization of billet hot charging of heat delivery and on-line often, controlled rolling and air cooling and other processes.
Breakout accident
Breakout accident is great danger of casting production in the production of the accident. Breakout accident, not only affects the continuous casting, serious damage to the mold, roller, increasing the amount of continuous casting equipment repair and maintenance costs, resulting in huge economic losses, but also a huge security risk. It is estimated that a "normal" breakout accident resulting directly or indirectly, the economic loss will reach $ 200,000.
To reduce the breakout occurs, it has been developing breakout prediction system. By sensors mounted on the mold, it has been able to use automated control system to effectively reduce the breakout rate.
The first breakout prediction are: (1) estimates mold water temperature; (2) detection of mold and the friction between the slab; (3) buried in the local heat flux sensor monitoring; (4) in the copper mold embedded copper thermocouples for thermal monitoring. This method is now widely used, proven to be more effective in detecting and forecasting bond breakout technology. Based on temperature detected for breakout prediction of the theory is: As the breakout is often accompanied by copper mold temperature, mounted on copper by monitoring the temperature of the thermocouple on the changes made according to certain methods to determine the breakout.
Overview of the breakout prediction based on temperature prediction methods, there are three main technical approaches. They are the logic method, neural network methods and multivariate statistical methods.
Most of the new steel mills in China in recent years on the casting machine used in breakout prediction system is based on logic approach produced steel pipe,like seamless steel tube and piling pipe for construction. Implementation of the forecasting method does not require a lot of raw data, especially for the new casting machine. But the logic to set the parameters and conditions of the type of steel, technology and the environment have a great relationship, the model has some limitations.
Neural network breakout prediction method using neural network technology to the scene of breakout data for learning, coupled with the process conditions necessary for a breakout to identify the characteristics of the thermocouple temperature curve, and then make a breakout prediction . Complete neural network system must be able to significantly increase the breakout prediction accuracy, but the neural networks that exist in the breakout prediction of its limitations. Complete neural network must be a large number of training samples, the sample will not lead to a comprehensive network of dysfunction. Second, continuous casting machines working conditions are very complex, many factors, access to sample data on serious interference, in order to be completely ruled out with a sample of the noise is almost impossible. Casting in some special circumstances, such as open water, for the final package and pouring so neural network system to become unstable; for the new continuous casting machine, neural network is not feasible, must be combined with other methods.
Multivariate statistical process control (MSPC) method is based on principal component analysis (PCA) and partial least squares (PLS) method for continuous monitoring of process control methods. In the continuous casting process, especially in the breakout prediction process, MSPC method very few applications.
To reduce the breakout occurs, it has been developing breakout prediction system. By sensors mounted on the mold, it has been able to use automated control system to effectively reduce the breakout rate.
The first breakout prediction are: (1) estimates mold water temperature; (2) detection of mold and the friction between the slab; (3) buried in the local heat flux sensor monitoring; (4) in the copper mold embedded copper thermocouples for thermal monitoring. This method is now widely used, proven to be more effective in detecting and forecasting bond breakout technology. Based on temperature detected for breakout prediction of the theory is: As the breakout is often accompanied by copper mold temperature, mounted on copper by monitoring the temperature of the thermocouple on the changes made according to certain methods to determine the breakout.
Overview of the breakout prediction based on temperature prediction methods, there are three main technical approaches. They are the logic method, neural network methods and multivariate statistical methods.
Most of the new steel mills in China in recent years on the casting machine used in breakout prediction system is based on logic approach produced steel pipe,like seamless steel tube and piling pipe for construction. Implementation of the forecasting method does not require a lot of raw data, especially for the new casting machine. But the logic to set the parameters and conditions of the type of steel, technology and the environment have a great relationship, the model has some limitations.
Neural network breakout prediction method using neural network technology to the scene of breakout data for learning, coupled with the process conditions necessary for a breakout to identify the characteristics of the thermocouple temperature curve, and then make a breakout prediction . Complete neural network system must be able to significantly increase the breakout prediction accuracy, but the neural networks that exist in the breakout prediction of its limitations. Complete neural network must be a large number of training samples, the sample will not lead to a comprehensive network of dysfunction. Second, continuous casting machines working conditions are very complex, many factors, access to sample data on serious interference, in order to be completely ruled out with a sample of the noise is almost impossible. Casting in some special circumstances, such as open water, for the final package and pouring so neural network system to become unstable; for the new continuous casting machine, neural network is not feasible, must be combined with other methods.
Multivariate statistical process control (MSPC) method is based on principal component analysis (PCA) and partial least squares (PLS) method for continuous monitoring of process control methods. In the continuous casting process, especially in the breakout prediction process, MSPC method very few applications.
Thick-walled stainless steel roll forming method
Roll forming method using thick-walled stainless steel tube rolling machine for rolling sheet metal is also available a variety of thick-walled stainless steel tube, steel pipe manufacturing process of this method is very simple, it does not require any special tooling to properly adjust the three-roll only between 678 distance, and if the diameter required for bending forming insufficient material utilization of this method to implement a high heat, but the drawback is that not only production but production of seamless steel tube joints. This gap welding to sew through follow-up, modern welding technology for welding cracks grow continuously improved, but performance is difficult to ensure the welds are consistent with the bulk properties, as well as the quality of welds, because the risk of the pipeline to withstand high-pressure fluid section a vertical cross-section, rolled steel welds and exactly vertical, so the pipe to withstand high temperature and pressure generally do not roll steel.
Thick-walled stainless piling pipe to the inventory of the market has been gradually advancing, the current gradually increased upside risks to price, do not rule out the recent correction may Steel City again, thick-walled seamless steel pipe stock price is lower than the strong spot market prices will steel will be forced to walk up. Thick-walled seamless steel pipe production capacity of the market growth is slow, once the market recovery and prosperity, few big steel mills surrounded them, China's steel industry will create a positive external environment. Adjustment disorder at home and could not ex-steel city, large enterprises are also actively involved in steel production, to reduce the homogenization of competition. Thick-walled seamless steel pipe production country backward steel production capacity of the case has not been much progress, mainly iron and steel enterprises are still operating at full capacity production. Thick-walled seamless steel prices at home and by consumer demand season, the impact of steel, at any time may be bottoming out, or even thick-walled seamless steel pipe sales rebounded strongly.
Thick-walled stainless piling pipe to the inventory of the market has been gradually advancing, the current gradually increased upside risks to price, do not rule out the recent correction may Steel City again, thick-walled seamless steel pipe stock price is lower than the strong spot market prices will steel will be forced to walk up. Thick-walled seamless steel pipe production capacity of the market growth is slow, once the market recovery and prosperity, few big steel mills surrounded them, China's steel industry will create a positive external environment. Adjustment disorder at home and could not ex-steel city, large enterprises are also actively involved in steel production, to reduce the homogenization of competition. Thick-walled seamless steel pipe production country backward steel production capacity of the case has not been much progress, mainly iron and steel enterprises are still operating at full capacity production. Thick-walled seamless steel prices at home and by consumer demand season, the impact of steel, at any time may be bottoming out, or even thick-walled seamless steel pipe sales rebounded strongly.
Tuesday, June 4, 2013
How to raise the temperature by controlling the welding seam steel pipe piling surface quality
The strip is into the welded pipe unit, the multi-channel roll rolling, gradually rolled strip steel, formed with an opening gap round tube, adjust the amount of reduction squeeze rollers, so that the weld gap control in 1 ~ 3mm, and to weld ends flush. If the gap is too large, resulting in reduced proximity effect, eddy current lack of heat, poor weld joint between grain yield incomplete fusion or cracking. If the gap is too small, causing the proximity effect increases, excessive soldering heat, causing the weld burning; or weld by extrusion, rolling to form a pit, the impact piling pipe weld surface quality.
Soldering temperature is mainly affected by the impact of high-frequency eddy current heating power, according to the relevant formula, high-frequency eddy current frequency heating power is mainly affected by the impact of thermal power and eddy current excitation frequency is proportional to the square; while current excitation frequency but also by the excitation voltage, current and capacitance, inductance. Excitation frequency formula is:
f = 1 / [2π (CL) 1/2]
The formula: f-excitation frequency (Hz); C-excitation circuit of the capacitance (F), capacitance = power / voltage; L-excitation loop, inductance = flux / current
The above formula, the excitation frequency of the excitation circuit capacitance, inductance is inversely proportional to the square root, or the voltage and current proportional to the square, as long as the change in the circuit capacitance, inductance, or voltage and current can change the size of the excitation frequency, so as to achieve control of welding temperature. For low carbon steel, welding temperature control in the 1250 ~ 1460 ℃, can meet the pipe wall thickness 3 ~ 5mm penetration requirements. In addition, the soldering temperature can be achieved by adjusting the welding speed.
Heat input is low, the heated soldering temperatures reach the edge of the weld metal structure remains solid, forming incomplete fusion or penetration; when the input hot enough, over the edge of the weld is heated soldering temperatures, resulting in over-burn or melt drops, so that the weld formation Cave.
Soldering temperature is mainly affected by the impact of high-frequency eddy current heating power, according to the relevant formula, high-frequency eddy current frequency heating power is mainly affected by the impact of thermal power and eddy current excitation frequency is proportional to the square; while current excitation frequency but also by the excitation voltage, current and capacitance, inductance. Excitation frequency formula is:
f = 1 / [2π (CL) 1/2]
The formula: f-excitation frequency (Hz); C-excitation circuit of the capacitance (F), capacitance = power / voltage; L-excitation loop, inductance = flux / current
The above formula, the excitation frequency of the excitation circuit capacitance, inductance is inversely proportional to the square root, or the voltage and current proportional to the square, as long as the change in the circuit capacitance, inductance, or voltage and current can change the size of the excitation frequency, so as to achieve control of welding temperature. For low carbon steel, welding temperature control in the 1250 ~ 1460 ℃, can meet the pipe wall thickness 3 ~ 5mm penetration requirements. In addition, the soldering temperature can be achieved by adjusting the welding speed.
Heat input is low, the heated soldering temperatures reach the edge of the weld metal structure remains solid, forming incomplete fusion or penetration; when the input hot enough, over the edge of the weld is heated soldering temperatures, resulting in over-burn or melt drops, so that the weld formation Cave.
Piling steel surface treatment process
Piling pipe uses a dual wire, double submerged arc welding under the flux layer of the method using the wire and solder layer between the flux produced by the combustion heat of the arc, the molten solder and base metal wire is formed. The main features of the product one-sided submerged arc welding, not only the deposition rate, but also has deep penetration capability; Second, the arc and the weld zone is well protected, weld quality, compact, good weld appearance and smooth, able to meet various performance requirements of the weld.
Piling steel surface treatment process:
1 steel surface treatment, piling steel pipe manufacturer in order to avoid formation of oxide scale unwinding and formation process, shall establish a board cleaning device.
2 steel edge processing, steel side piling up rust and deburring devices to reduce the porosity may occur. The location of the best cleaning device installed in edge milling machine, cutting disc, the device structure is a plane wave can adjust the position of the gap capstan, fluctuating pressure plate edges.
3 weld profile, weld factor is too small, narrow and deep weld, gas and inclusion is not easy come, easy formation porosity and slag. General weld coefficient control at 1.3 - 1.5, thick-walled pipe welding maximum, minimum, thin walls.
4. Reduce secondary magnetic field in order to reduce the impact of magnetic blow, to make the position of the workpiece welding cable connections only from the solder terminals, avoiding some welding cable to the workpiece to produce secondary magnetic fields.
Piling steel surface treatment process:
1 steel surface treatment, piling steel pipe manufacturer in order to avoid formation of oxide scale unwinding and formation process, shall establish a board cleaning device.
2 steel edge processing, steel side piling up rust and deburring devices to reduce the porosity may occur. The location of the best cleaning device installed in edge milling machine, cutting disc, the device structure is a plane wave can adjust the position of the gap capstan, fluctuating pressure plate edges.
3 weld profile, weld factor is too small, narrow and deep weld, gas and inclusion is not easy come, easy formation porosity and slag. General weld coefficient control at 1.3 - 1.5, thick-walled pipe welding maximum, minimum, thin walls.
4. Reduce secondary magnetic field in order to reduce the impact of magnetic blow, to make the position of the workpiece welding cable connections only from the solder terminals, avoiding some welding cable to the workpiece to produce secondary magnetic fields.
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