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.
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