Features and performance, 1.  Simple and reliable, it is used to prevent fluids from flowing back.2.  Convenient to repair and maintain.   Standards:Designing & manufacturing are according to the regulations of ANSI16.34, API 6D,DIN 3352 and BS 1414.Flange is subject to ANSI 16.5, MSS-SP-44, API 605, ISO 7005.Face-to-face dimension is ANSI 16.10, ISO 5752, DIN 3202.Pressure test is according to API 598, ISO 5208.*Please contact us for items made according to other standards.