... :320 360 410 460 490 Carbon and carbon-manganese steel seamless pipe for ship-----American Petroleum Institute:Certificate of Authority to use ... ahead in the international market. Our mainly products are material seamless steel tubes, alloy pipes, boiler tubes, high pressure boiler ... ,GB3088-82, GB17396-98,DIN17195-79, ST45.8-III, YB235-70, YB528-65, GB5312-85, API5CT, ASTMA53B SAS106B, API5L, GB3094- ...