... ~1mm/m4 Inside Roughness:0.4~0.8umsteel pipes for hydraulic useMaterial: C20, CK45, etc. also ST52 if given enough ... in 2009.Production Equipment Liaocheng Xinglong Seamless Steel Tube Manufacturing Co, Ltd. has equipped 60, 90, 140 and 325 mill lines. ... industry, Electrical Power, Coal, Machinery, Low and high-pressure boiler, hydraulic prop and so on.InvitationWelcome to Our two factories. I ...