Spiral welded pipe flaw detection testing

Spiral welded pipe steel is heated to quenching above the critical temperature, holding time, then quickly into the quenching agent, so that the temperature suddenly decreased, the critical cooling rate greater than the speed of rapid cooling, to obtain the martensite imbalance based organization heat treatment method. Quench can increase the strength and hardness of steel, but to reduce its plasticity. In China, good performance is still not suitable for large-diameter steel pipe produced magnetic flux leakage testing equipment, use of which is imported. Imports of magnetic flux leakage testing equipment is expensive for the majority of domestic enterprises difficult to accept.

The end of April this year, U.S. exports to China its most important oil pipeline starts "dual" survey, involving more than $ 2.6 billion, more than the tires safeguard the two billion U.S. dollars. Spiral welded pipe strength is generally higher than the Longitudinal, can produce a narrower diameter than the blank large pipe, you can also use the same width of billet production of different pipe diameters. API-5L (American Petroleum Institute, also known as line pipe; but with the same length of straight seam tubes, weld length of 30 to 100%, and the production rate is low. Generally spiral low-pressure fluid transport submerged arc welded pipe, double-sided or single-sided submerged arc automatic welding method as for water, gas, air and steam.
       
Past two years, including spiral pipe specifications, including a Sino-US trade friction and the weight of industry the hardest hit, the U.S. has several GB of steel products to China spiral pipe size weight "double reverse", the value of the case the case of seamless steel tube about four billion U.S. dollars, the U.S. International Trade Kunshan Teflon tube to the same italian decision is very high.
     
Quenching pipe commonly used quenching agents are: water, oil, alkali and salt solution, and so on. Oil pipe imported from Japan for more than half of total imports. Spiral welded pipe(SAWL pipe) for testing at home and abroad, the general magnetic or pressure leakage test. Spiral welded pipe strength is generally higher than the Longitudinal, can narrow billet production with a larger diameter pipe, you can also use the same width of the billet production of different pipe diameters. But with the same length of straight seam pipe compared to the weld length of 30 to 100, and a lower production rate. Therefore, the smaller diameter pipe actually use straight seam welding, large diameter spiral welded pipe is mostly used.