Design standards
API 6D, ANSI B16.34, BS5351
Fire safety standards 
BS6755 the PART 2, API607 4TH 
Seat leakage rating 
DIN 3 230 the PART 3 The RATE 2, better than the ANSI B16.104CLASS VI
Stem external leakage class in accordance with
the TA-LUFT, as well as the external EPA emission standards
Processing standards of the flange
ANSI B16.5 Class, RF flange, or RTJ, SW flange
Flange face to face, size standard
A NSI B16.10