... ISO9001, API 5L Perennial: stainless steel plate, seamless steel pipe, thick wall steel pipe, round steel, square tube, rectangular tube.Products: pipe: (GB/T8162-2008): (GB/ ... tube: (GB/T9948-2006), hydraulic prop tube: (GB/T17396-1998), fertilizer dedicated tube: (GB/T6479-2000), drilling pipe (: GB/T9808-2008), ... 27SIMN, 37MN5, 35MN2V, 42CRMO, 40CR and other kinds of MN steel seamless steel pipe