... Certificate: ISO9001, API 5L Perennial: stainless steel plate, seamless steel pipe, thick wall steel pipe, round steel, square tube, rectangular tube.Products: pipe: ... pressure alloy pipe: (GB/T5310-2008) and a series of steel products.Material: 10#, 20#, 35#, 45#, 20G, 20Gr- ... .The company in the long-term business with major steel mills to establish a long-term stable cooperative relations between ...