... ,00C rl7Nil4Mo2,0C r18Ni9Ti etc. 2. Standard:GB/T5312-------Chinese National Standard Vessel Seamless Steel Pipe1. Material: 320,360,41 0 ... Material and Welding----China Classification SocietyGB/ T5312-------Chinese National StandardGB/T14976-------Chinese National StandardDNV Regulations------Det Norske Veritas Approval of ManufacturerLR Regulations ...