Astm a 53 standard specification for pipe, steel, black and hot-dipped, zinc-coated, welded and seamless Astm a519 seamless carbon and alloy steel mechanical tubing gb/t8162 seamless steel tubes for structural purposes Jis g3441 alloy steel tubes for machine purposes jis g3444 carbon steel tubes for general structural purposes Jis g3445 carbon steel tubes for machine structural purposes Din 2391 seamless precision steel tubes En10305 steel tubes for precision applications. Technical delivery conditions. Seamless cold drawn tubes En 10210:seamless structural steel pipes. MOQ 1 mt.