Pipefitter Pipe Testing and Inspection 5 — Questions and Answers
Question 1: What is the correct sequence of steps when isolating a section of piping for a pressure test using spectacle blinds?
- Install blind, depressurize, test, remove blind
- Depressurize, install blind, test, remove blind and restore (Correct answer)
- Test with blind in place, then depressurize and remove
- Remove existing gaskets, install blind, test without depressurizing
Correct answer: Depressurize, install blind, test, remove blind and restore
The line must be depressurized and isolated before installing the spectacle blind; testing is then performed, and the blind is removed to restore flow after the test.
Question 2: In radiographic testing (RT) of a weld, what does a 'density' reading refer to?
- The thickness of the base material
- The darkness of the radiographic image (Correct answer)
- The porosity level within the weld
- The pressure applied during the test
Correct answer: The darkness of the radiographic image
Density in RT refers to the degree of blackening on the radiographic film, which is controlled to ensure defects of the minimum required size are detectable.
Question 3: Which ASME code governs the testing requirements for process piping systems in industrial facilities?
- ASME B31.1
- ASME B31.3 (Correct answer)
- ASME Section VIII
- ASME B16.5
Correct answer: ASME B31.3
ASME B31.3, Process Piping, governs the design, fabrication, and testing requirements for piping in chemical and industrial process plants.
Question 4: When a piping system cannot be hydrostatically tested due to structural limitations, what alternative test may be used with additional precautions?
- Vacuum test
- Pneumatic test (Correct answer)
- Visual inspection only
- Thermal imaging test
Correct answer: Pneumatic test
A pneumatic test using compressed gas may be substituted for hydrostatic testing when the system cannot support the weight of water, but it requires additional safety precautions due to stored energy hazards.
Question 5: What is the significance of a 'zero-leakage' requirement in a seat leakage test for valves?
- No leakage is permitted past the valve seat at test pressure (Correct answer)
- The system pressure must remain at zero before testing
- The valve stem packing must have zero friction
- There must be no leakage from the valve body external surface
Correct answer: No leakage is permitted past the valve seat at test pressure
Zero-leakage seat testing (Class VI per ANSI/FCI 70-2) means no measurable fluid passes the closed valve seat during the test, required for critical shut-off applications.
Question 6: A pipefitter is asked to perform a 'soap bubble test.' Which type of pressure test is this method commonly used to verify?
- Hydrostatic test for maximum leak rate
- Pneumatic or gas leak test for joint tightness (Correct answer)
- Vacuum integrity test for cryogenic lines
- Radiographic test for weld soundness
Correct answer: Pneumatic or gas leak test for joint tightness
The soap bubble method is a simple, effective technique for locating leaks during pneumatic or gas pressure tests by applying soap solution to joints and watching for bubbles.
Question 7: What does 'MAWP' stand for and why is it critical during pipe testing and inspection?
- Maximum Allowable Working Pressure — the upper pressure limit the system is designed to safely handle (Correct answer)
- Minimum Acceptable Water Pressure — the lowest pressure for hydrostatic testing
- Maximum Actual Water Pressure — recorded during a hydrostatic test
- Measured Allowable Weld Pressure — the burst threshold of a weld joint
Correct answer: Maximum Allowable Working Pressure — the upper pressure limit the system is designed to safely handle
MAWP (Maximum Allowable Working Pressure) defines the safe operating pressure limit; test pressures are calculated as a multiple of MAWP to verify the system can handle normal and surge conditions.
Pipefitter Pipe Testing and Inspection 5
What is the correct sequence of steps when isolating a section of piping for a pressure test using spectacle blinds?