Requirments:
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Required protective coating such as paint, which may mask surface defects, shall not be applied to any surface before inspection or pressure testing.
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The valve shall be essentially free from the trapped air during the pressure test.
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Valves designed to permit emergency or supplemental introduction of an injectable sealant to the seat area shall be tested with the injection system empty and not in use
Backseat test
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Backseat test is done for all valves except bellow valves.
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Backseat test is performed by applying pressure inside the assembled valve with the valve ends closed, the valve fully open, and the packing gland loose or packing not installed. Ensure the valve is not leaking
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Backseat test can be performed with packing gland if backseat test is doing after shell test.
Shell test
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The shell test shall be made by applying the pressure inside the assembled valve with:
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Valve ends are closed
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Valve partially open
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Any packing gland tight enough to maintain the test pressure.
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Low pressure closure test
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For this test, seat sealing surface must be clean from oil and grease.
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If necessary to prevent galling, the sealing surfaces may be coated with a film of oil that is not heavier than kerosene.
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The sealing or closures are covered with water or coated with a soap or similar solution. So any leakage at the seat sealing, seat ring or through disc can be detected easily.
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For valves that close for high pressure on both sides, the pressure shall be applied in both directions with the closed valve with the other side open to the atmosphere to check for leakage at the atmospheric side of the closure.
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While closure test is required only in one direction for butterfly valves.
High-pressure closure test:
The procedure for high-pressure closure test is same as the low-pressure closure test, except there is a change, the leakage is detected only when the fluid drops instead of bubbling.