ISO 5208:2008 pdf download – Industrial valves – Pressure testing of metallic valves
1 Scope
This International Standard specifies examinations and tests that a valve manufacturer needs to act upon in order to establish the integrity of the pressure boundary of an industrial metallic valve and to verify the degree of valve closure tightness and the structural adequacy of its closure mechanism. This International Standard is to be applied in conjunction with the specific requirements of a valve product standard to the extent cited by the product standard as a normative reference. Where requirements of a product standard differ from those given in this International Standard, the requirements of the product standard apply. This International Standard does not cover safety aspects of pressure testing.
2.7 DN, NPS, A
alphanumeric designation of size that is common for components used in a piping system, used for reference purposes, comprising the letters DN or NPS followed by, or the letter A preceded by, a dimensionless number indirectly related to the physical size of the bore or outside diameter of the end connections
NOTE The number following DN or NPS or preceding A does not represent a measurable value and is not used for calculation purposes except where specified in a product standard.
2.8 PN or Class
alphanumeric designation for pressure-temperature rating that is common for components used in a piping system, used for reference purposes, comprising the letters “PN or Class” followed by a dimensionless number indirectly related to the pressure retaining capability as a function of temperature of the component
NOTE The number following “PN or Class” does not represent a measurable value and is not used for calculation purposes except where specified in a product standard. There is no definitive correlation that links PN designations to Class designations.
4.12.4.2 For valves, including combination non-return types fitted with manual or power actuated torque multiplying devices, the required high-pressure closure test shall be performed at 110 % of the obturator design differential pressure used to size the device. The identification plate that the manufacturer affixes to the valve shall include this design pressure differential limitation.
4.12.4.3 Valves that are designed for operating conditions in which the pressure differential across the obturator is limited to values less than the CWP rating, because obturator actuating devices (direct, mechanical, fluid or electrical) would likely be damaged by or be incapable of function at high differential pressures, may be tested at a lower closure pressure than prescribed in 4.12.4.1 b). This exception may be exercised only by agreement between the manufacturer and valve purchaser. The closure test pressure shall then be at × 1,1 the design differential pressure value. The identification plate that the manufacturer affixes to the valve shall include the design pressure differential limitation.