SY/T5037-2000,GB/T9711.1-1997, APISpec5L standards. And the material adopts Q235, Q345, 10#, 20#, 16mn, L245, L290, L360,X42-X70. Our products widely uses in the electric power, the thermal energy, offshore oil piling, chemicals, water supply , transporting natural gas, petrol , piling, building bridge, steel structures, and other engineering fields.