1)size:500 to 6300mm 2)Materials:alloy steel,carbon and stainless steel 3)Certificates:9 classification ship(DNV,BV,ABS,GL.etc Advantage:1--Quality control and management to the whole produce process, including material inspection, forging, heat treatment, machining and strictly final inspection by Technology Department,Production department,Quality assurance department. 2--Excellent quality and ...