... 5)Standard: ASTM BS GB JIS APISize(O.D)Wall thickness (W.T.)15mm*15mm-600mm*600mm0.5mm-30mmLength2m ... , we have always adhered to the business policy as "Quality for Survival, Product for Development, Credibility for Cooperation and ... welded steel pipe manufacturing group. We have cooperated with Bao steel, Wu yang steel, TPCO, Baotou steel, Shou gang Jin tang Steel, An gang Steel, Daye Steel, ...