The recent development of grade X120 high strength pipeline steel offers opportunity of reducing total cost 5%~15% to long distance gas transmission pipeline for natural gas producer and further decrease the price of transmission natural gas to the market.

The study focuses on such aspects as change of the mechanical properties of the X120 steel plate, the forming characteristics, weldability and softening of the heat af- fected zone(HAZ)of JCOE, the comparative testing with rectangular and round tensile test pieces and the influ- ences by different welding material proportions and welding thermal inp.

,pipeline steel with high deformability for unstable geological region or deep sea environment according strain design principle,the anti-erosion pipeline steel for slurry pipe line,the X100/X120 pipeline steel for long distance natural gas delivery,the new welding material and technique for X100/X120 pipeline steel welding and counte.

Experiment of Deoxidation and Desulphurization for X120 Pipeline Steel Melting by Vacuum Induction Furnace;

2—1999 are widely used by pipe manufacturer and due to the discrepancy among standards or shortage of itself,there are many problems occur such as disunity of steel grade,for hydrostatic test,testing pressure may be different for same size and steel grade,for bend test,there are many choices for module diameter and so on.