Process:erw (electric resistance welded) HFI (high frequency induction) EFW(electric fusion welded tube)quality standard:erw hfi , efw, :gb/t3091 welded steel pipe for low pressure liquid deliverygb/t9711 petroleum and natural gas industries--steel pipe for pipelinesis: 3589 steel tubes for water and sewageis : 1978-1982? steel tubes for use in transportation of oil; gas & petroleum products?bs: 1387 steel tubes for use for water, gas, air and steamastm a53 standard specification for pipe, steel, black and hot-dipped, zinc-coated, welded and seamlessdin 2458 welded steel pipes and tubesen10217 welded steel tubes for pressure purposes. Technical delivery conditions. Non-alloy steel tubes with specified room temperature propertiesapi 5l line pipecoating standard:ansi/awwa c104/a21.4 american national standard for cement-mortar lining for ductile-iron pipe and fittings for wateriso 21809 petroleum and natural gas industries - external coatings for buried or submerged pipelines used in pipeline transportation systemsdin 30670 polyethylen coatings of steel pipes and fittings. Moq 1 mt.