3. Standard: GB/T9711-1997, ASTM A 53, DIN, JISG APL 5L/5CT (PSL1, PSL2)  (GB/T3091, ASTM A 53, API 5L, API 5CT, DIN 1626/2-2458)

4. Grade: Q195, Q235,Q345, SS300, SS400,ST33, ST37, S235JR,A,B, X42-X70