... mm 4.Place of origin:China 5.Certificate:API.ISO9001:2000.BV structure seamless pipeHebei shengtian (group) seamless steel pipe Co,. LtdWe manufacture ... ;ASTMA252 Gr.2,Gr.3; ST37,ST42,ST52;Gr.B,X42,X46,X52,X56,X60,X65,X70, etc11.Usagefor petroleum/ natural ... gas pipeline , for conveying water,drainage,coal gas, mineral slurry and other low-middle pressure ...