MSS SP-75 standard
They are typically used to connect to API 5L pipes or ASTM A694 forged pipe flanges. MSS SP-75 Grade WPHY 60, 65, and 70 are used a lot in the high pressure oil and gas pipeline fittings, for WPHY-42, 46, 52 and 56, they are working in a medium-high pressure pipelines, so mostly client may choose with ASTM A234 WPB or WPC instead. Materials