Pipefitter Pipe Testing and Inspection 4 — Questions and Answers
Question 1: When performing a pneumatic pressure test, what is the maximum test pressure typically allowed before a preliminary check at a lower pressure is required?
- 25 psig
- 50 psig (Correct answer)
- 100 psig
- 150 psig
Correct answer: 50 psig
ASME B31.3 requires a preliminary pneumatic leak check at no more than 10 psig, with full test pressure not exceeding 1.1 times design pressure, and a 50 psig incremental hold is standard before raising pressure further.
Question 2: Which type of inspection method is used to detect surface and near-surface discontinuities in non-magnetic piping materials?
- Magnetic particle testing (MT)
- Liquid penetrant testing (PT) (Correct answer)
- Radiographic testing (RT)
- Ultrasonic testing (UT)
Correct answer: Liquid penetrant testing (PT)
Liquid penetrant testing (PT) is suitable for non-magnetic materials to detect surface-breaking defects, while magnetic particle testing requires ferromagnetic material.
Question 3: During a hydrostatic test, at what point should a visual inspection of all joints and connections be performed?
- Before pressurizing the system
- While raising pressure to test level
- After reaching and holding test pressure (Correct answer)
- Only after depressurizing the system
Correct answer: After reaching and holding test pressure
Visual inspection for leaks is conducted after the system has reached and stabilized at full test pressure and the required hold time has begun.
Question 4: What is the purpose of a 'soak period' during a hydrostatic leak test?
- To allow the pipe to thermally expand fully
- To allow pressure to stabilize before reading gauges (Correct answer)
- To flush out air pockets trapped in the system
- To allow the test pump to cool down
Correct answer: To allow pressure to stabilize before reading gauges
The soak period allows pressure to stabilize throughout the system so that an accurate, steady gauge reading can be taken before the final inspection.
Question 5: A pipefitter notices the pressure gauge drops slightly during a hydrostatic test but no leaks are visible. What is the FIRST step to investigate?
- Immediately re-pressurize the system
- Check for temperature changes in the test fluid (Correct answer)
- Assume the gauge is faulty and replace it
- Drain and disassemble all joints
Correct answer: Check for temperature changes in the test fluid
A temperature drop in the test fluid causes volume contraction, which can result in a pressure decrease without any actual leak, and should be investigated first.
Question 6: Which document records the results of a completed pipe pressure test and must be retained as part of the quality record?
- Weld map
- Test report or test record (Correct answer)
- Material certification (MTR)
- P&ID drawing
Correct answer: Test report or test record
A test report documents the test medium, pressure, duration, date, inspector signature, and results, serving as the permanent quality record for the completed test.
Question 7: When using a deadweight tester during a hydrostatic test, what is its primary advantage over a standard Bourdon tube gauge?
- It is less expensive and easier to use
- It provides a highly accurate primary pressure standard (Correct answer)
- It can measure negative (vacuum) pressures
- It does not require calibration
Correct answer: It provides a highly accurate primary pressure standard
A deadweight tester applies known weights to generate precise pressure and is considered a primary pressure standard, offering higher accuracy than a Bourdon tube gauge.
Pipefitter Pipe Testing and Inspection 4
When performing a pneumatic pressure test, what is the maximum test pressure typically allowed before a preliminary check at a lower pressure is required?