5. Pre-welding: make straight seam welded steel pipe seam after forming and using gas welding (MAG) for continuous welding; 6 in the welding: The tandem multi-wire submerged arc welding (up to four wire) in straight stitch inside of the pipe welding; 7. Welded: The tandem multi-wire submerged arc welding on the outside of LSAW steel pipe welding; The ultrasonic inspection Ⅰ: inside and outside of the straight seam welded steel pipe on both sides of the base metal and weld seam 100% inspection; 9.X-ray inspection Ⅰ: internal and external welds 100% inspection of X-ray television industry, the use of image processing system to ensure detection sensitivity; 10. flaring: for submerged arc welding straight seam steel pipe expanding the entire length of the steel pipe in order to improve dimensional accuracy and to improve the distribution of internal stress of the steel pipe; 11. The hydrostatic test: On pressure testing machine after expanding the steel pipe by-root test to ensure that the steel pipe to meet the standards required test pressure, the machine has an automatic recording and storage capabilities; knowledge presentation 16Mn straight seam steel clad steel seamless pipe due to low carbon content distributors, hardening tendency decreases, cold cracking tends to decrease. But as the intensity level increases, increasing the thickness of saponification seamless steel tubes, still has a certain tendency to cold cracking. When the field is often used because of cellulose electrode welding, self-shielded flux-cored wire and other high hydrogen content of welding consumables, line energy is small, fast cooling, cold cracking susceptibility increases seamless steel tubes, welded need to take the necessary measures to such as preheating before welding. HAZ embrittlement is often caused by broken straight seam steel 16Mn, induced root cause catastrophic accidents. Partial embrittlement has two main areas, namely the heat-affected zone CGHAZ embrittlement is due to over-grown grains overheated zone and the formation of undesirable tissue caused by the multi-layer welding CGHAZ another critical embrittlement acid wash treated seamless steel pipe, which CGHAZ again before the weld by heating the two-phase region caused subsequent passes. This is done by adding a certain amount in the steel Ti, Nb micro alloying elements and control weld cooling rate to get the right t8 / 5 to improve toughness. With 16Mn straight seam reduce the carbon content of steel, welding reduced sensitivity to hydrogen induced cracking, in order to avoid cracking process measures needed to reduce the extent of damage reduced performance weld heat affected zone. However, due to the welding seam steel 16Mn straight through a series of complex physical and chemical non-equilibrium processes, which may cause defects in the weld zone, or the joint performance degradation, mainly weld cracking problems and HAZ embrittlement problem. Pickling seamless steel pipe manufacturers, the virtues of Industry (certified), Laiwu seamless steel pipe industry by virtue of Liaocheng Limited. Liaocheng virtue Pipe Co., Ltd. (www.meidegc.com) (www.meidegc.com) (www.mdwfg.com) (www.mdggc.com) Shandong Liaocheng, steel leader, over the years, the company is implementing the scientific management, innovation and development, the principle of honesty and trustworthiness, and satisfy customer needs. Industry leaders in the United States and Germany with the staff warmly welcome all inquiries negotiations to create the virtues pipe industry a better future.