Pressure Testing & Commissioning Flashcards
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Read the first 7 Pressure Testing & Commissioning flashcards as text
What is the minimum ambient temperature requirement for conducting a hydrostatic pressure test on carbon steel piping to prevent brittle fracture?
Answer: Above 60°F (16°C) or at least 30°F above the DBTT
Testing must be performed above the ductile-to-brittle transition temperature (DBTT)—typically above 60°F or 30°F above DBTT—to avoid brittle fracture during hydrostatic testing.
Which leak test method is specifically required by ASME B31.3 as an alternative for systems where hydrostatic testing is not practical?
Answer: Pneumatic test per B31.3 para. 345.5
ASME B31.3 para. 345.5 provides specific pneumatic test requirements as the code-recognized alternative when hydrostatic testing is not feasible.
During commissioning, a 'functional test' of a pressure safety valve (PSV) verifies which parameter?
Answer: Actual lift pressure matches the set point stamped on the nameplate
A functional test (or pop test) confirms that the PSV opens at its nameplate set pressure, ensuring it will protect the system at the correct pressure.
What is the purpose of nitrogen blanketing a piping system after a hydrostatic test and before drying?
Answer: To prevent oxygen ingress and internal corrosion while water is removed
Nitrogen blanketing displaces oxygen during post-test drainage and drying operations, preventing internal corrosion on bare pipe surfaces exposed to residual moisture.
Which document provides the step-by-step instructions for introducing hydrocarbon feed into a process unit for the first time during commissioning?
Answer: Initial fill and startup procedure
The initial fill and startup procedure (or first-fill procedure) provides the detailed, sequenced steps for safely introducing process fluid into a commissioned system.
When a piping system test fails due to a leak discovered at a threaded connection, what action is prohibited before re-testing?
Answer: Tightening the joint while the system is still pressurized
Tightening joints while the system remains pressurized is strictly prohibited because sudden failure can cause ejection of components and serious injury.
What is the purpose of a 'walk-down' inspection prior to initiating a pressure test?
Answer: To verify test boundaries, temporary supports, vent/drain positions, and instrument isolation
A pre-test walk-down ensures the physical system matches the test pack, all boundaries are set, vents and drains are properly positioned, and instruments are isolated.