item name:flat flanges( plate flange,metal flanges) Carbon Steel:ASTM A105,20# ... A350 LF1, LF2 CL1/CL2, LF3 CL1/CL2 item name: flat flanges( plate flange,metal flanges)Seal Cover:FFRFMFMTGRJMaterial: Carbon Steel ... : HG20601-1997,ANSI B16.5HG20622-1997GB/T9123.1-2000GB/T9123.4-2000 flat flanges( plate flange,metal flanges)