Typowe problemy
- Ball and seat wear leading to leakage past the closed valve, especially with abrasive or crystallizing cargoes
- Stem seal (packing) leakage after repeated cycling
- Seizure of the ball if left in one position for extended periods in cargo services prone to polymerization or crystallization
- Corrosion or pitting of wetted parts where valve material is not matched to the cargo carried
- Damage to the test connection/expansion tube from over-tightened or misaligned gauge fittings
- Gasket leakage at the flange connection to the manifold or gauge line
Lista kontrolna przeglądu
- Function-test the valve (open/close) and confirm smooth ball rotation without excessive torque
- Check for external leakage at the stem packing and flange gaskets
- Verify the vent bore/expansion tube is clear and functions as intended before disconnecting a pressure gauge
- Inspect for corrosion or product residue on wetted parts appropriate to the cargo carried
- Confirm the valve material certificate/marking matches the cargo compatibility requirement for the trade
- Check flange bolting condition and torque
Interwały serwisowe
| Function test (open/close cycling) | at each cargo operation or per the vessel's planned maintenance system, commonly checked before loading/discharge |
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| Stem packing inspection/renewal | condition-based on leakage, checked at scheduled planned-maintenance intervals - confirm against the manufacturer's guidance |
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| Full strip and internal inspection | per the vessel's class-approved planned maintenance schedule for cargo system valves rather than a fixed hour figure |
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Krytyczne części zamienne
- Ball and seat set
- Stem seal/packing kit
- Flange gasket
- O-rings for the test connection
Bezpieczeństwo
- This valve isolates a pressure gauge from the cargo system - confirm it is fully closed and depressurized via the vent/test connection before removing a gauge, to avoid a sudden release of cargo vapour or liquid
- Material compatibility with the specific cargo must be verified before use on chemical or gas trades - the wrong material can fail without warning
- ATEX-rated components must not be substituted with non-rated parts in a hazardous zone
Przegląd klasyfikacyjny
Cargo manifold and gauge valves on tankers are typically included in the vessel's cargo system planned maintenance and checked during class surveys of the cargo piping system for corrosion, leakage and correct material certification rather than surveyed as an individual item with its own interval.