API 510 Pressure Testing 4 — Questions and Answers
Question 1: When performing a sensitivity leak test using pneumatic pressure, what method is commonly used to detect leaks?
- Thermal imaging only
- Soap bubble solution or equivalent (Correct answer)
- Dye penetrant testing
- Magnetic particle testing
Correct answer: Soap bubble solution or equivalent
Soap bubble solution applied to joints and welds is the standard method for detecting leaks during pneumatic pressure testing.
Question 2: What is the typical pressure hold time required for a hydrostatic leak test per ASME Code?
- 5 minutes
- 10 minutes (Correct answer)
- 30 minutes
- 60 minutes
Correct answer: 10 minutes
ASME Code typically requires a minimum 30-minute hold at test pressure for hydrostatic tests before inspecting the vessel.
Question 3: A vessel with a corrosion allowance nearly consumed is scheduled for a pressure test. What special concern applies?
- Use a lower test multiplier
- Evaluate remaining wall thickness to ensure it can withstand test pressure without risk of failure (Correct answer)
- Skip the test and increase inspection frequency
- Apply internal coating before testing
Correct answer: Evaluate remaining wall thickness to ensure it can withstand test pressure without risk of failure
The remaining wall thickness must be verified to confirm the vessel can safely sustain the test pressure without risk of failure or plastic deformation.
Question 4: Which of the following best describes an 'alteration' to a pressure vessel per API 510?
- Any repair that restores original thickness
- A physical change that affects the pressure-containing capability beyond original design (Correct answer)
- Replacing insulation on the vessel exterior
- Painting or coating the exterior surface
Correct answer: A physical change that affects the pressure-containing capability beyond original design
An alteration is any physical change that affects the pressure-containing capability of the vessel beyond the original design.
Question 5: For a pressure vessel in cryogenic service, what special consideration applies when selecting a pressure test medium?
- Cryogenic fluids must always be used for testing
- Water or gas at ambient temperature may be used with appropriate precautions (Correct answer)
- Only nitrogen gas at cryogenic temperatures is acceptable
- Cryogenic vessels are exempt from pressure testing
Correct answer: Water or gas at ambient temperature may be used with appropriate precautions
Water or inert gas at ambient temperature is generally used for cryogenic vessel testing since the actual cryogenic fluid is not needed for the pressure test itself.
Question 6: What action should be taken when a pressure gauge used during testing reads erratically or is suspected to be inaccurate?
- Continue testing and note the anomaly
- Replace or calibrate the gauge before proceeding with the test (Correct answer)
- Use the vessel's installed process gauge as backup
- Estimate the test pressure based on pump stroke count
Correct answer: Replace or calibrate the gauge before proceeding with the test
An inaccurate gauge must be replaced or calibrated before testing continues to ensure the correct test pressure is applied.
Question 7: How many pressure gauges are typically recommended during a pressure test to ensure accuracy?
- One calibrated gauge is sufficient
- Two gauges — one at the pressure source and one on the vessel (Correct answer)
- Three gauges minimum at different elevations
- No gauges needed if a calibrated pump is used
Correct answer: Two gauges — one at the pressure source and one on the vessel
Using two gauges — one at the pressurization source and one on the vessel itself — provides verification of test pressure and detects any discrepancy.
API 510 Pressure Testing 4
When performing a sensitivity leak test using pneumatic pressure, what method is commonly used to detect leaks?