Welded steel pipes Usage: used for low pressure liquid delivery, such as water, gas, and oil. Process: Erw (electric resistance welded) Hfi (high frequency induction) Efw(electric fusion welded tube) Lsaw (longitudinal submerge-arc welded) uo(uoe)íórb(rbe)íójco(jcoe) Dsaw (double submerged arc welded) Saw (spiral welded) Ssaw (spiral submerged-arc welded) Quality standard: Erw hfi , efw, lsaw, dsaw: Gb/t3091 welded steel pipe for low pressure liquid delivery Gb/t9711 petroleum and natural gas industries--steel pipe for pipelines Is: 3589 steel tubes for water and sewage Is : 1978-1982 steel tubes for use in transportation of oil; gas & petroleum products Bs: 1387 steel tubes for use for water, gas, air and steam Astm a53 standard specification for pipe, steel, black and hot-dipped, zinc-coated, welded and seamless Din 2458 welded steel pipes and tubes En10217 welded steel tubes for pressure purposes. Technical delivery conditions. Non-alloy steel tubes with specified room temperature properties Api 5l line pipe In bundle, or according to your requirement