1. International Organisation for Standardisation classification of valve sealing classes
International Organisation for Standardization standard ISO 5208 "industrial valves metal valve pressure test".
2. American Petroleum Institute (APl) on the classification of valve sealing class American Petroleum Institute standard API 598 - 2004 "Valve Inspection and Testing".
3. American Valve and Pipe Fitting Industry Manufacturers' Standardization Association (MSS) classification of valve sealing class American Valve and Pipe Fitting Industry Manufacturers' Standardization Association standard "Pressure Test of Steel Valves" MSS SP61 allowable valve leakage requirements are as follows:
(1) Where plastic or rubber is used for one of the sealing surfaces in the valve sealing pair, there shall be no visible leakage for the duration of the sealing test.
(2) The maximum allowable leakage on each side when closed shall be: for liquids, 0.4 millilitres per millimetre, per hour for nominal size (DN); for gases, 120 millilitres per millimetre, per hour for nominal size (DN).
(3) The permissible leakage of the check valve can be increased by 4 times.
4. American National Standard / American National Instrumentation Association standards (ANSI / FCI) on the classification of control valve sealing grade
American National Standard Bin American Instrument Society standard ANSI/FCI70-2 (ASME B16.104) "control valve seat leakage".
5. European Union standards on the classification of valve sealing class
European standard EN 12266-1 "industrial valves valve test" Part l. Pressure test, test methods and acceptance criteria - mandatory requirements.