GPT Material Selection & Properties 2 — Questions and Answers
Question 1: Which pipe material is prohibited for use with LP-gas service in most US codes?
- Schedule 40 black steel
- Type K copper tubing
- CSST (corrugated stainless steel tubing)
- Cast iron (Correct answer)
Correct answer: Cast iron
Cast iron is prohibited for gas piping because it is brittle, prone to cracking, and cannot withstand vibration or soil movement.
Question 2: What is the minimum wall thickness designation required for steel pipe used in gas distribution systems per ASME B31.8?
- Schedule 10
- Schedule 40 (Correct answer)
- Schedule 80
- Schedule 160
Correct answer: Schedule 40
Schedule 40 is the minimum acceptable wall thickness for steel gas pipe under ASME B31.8 for most residential and commercial applications.
Question 3: A gas technician is installing pipe through a concrete floor slab. Which material requires a protective sleeve to prevent corrosion?
- CSST only
- PE only
- Black steel pipe (Correct answer)
- PVC conduit
Correct answer: Black steel pipe
Black steel pipe must be sleeved when passing through concrete because the alkaline environment accelerates corrosion of uncoated steel.
Question 4: What property of polyethylene (PE) pipe makes it unsuitable for above-ground gas service?
- It is not flexible enough
- It degrades when exposed to UV radiation (Correct answer)
- It cannot withstand pressures above 0.5 psi
- It reacts chemically with natural gas
Correct answer: It degrades when exposed to UV radiation
PE pipe degrades under UV radiation exposure, making it suitable only for buried underground applications.
Question 5: Which ASTM standard governs seamless and welded steel pipe commonly used in gas distribution?
- ASTM A53 (Correct answer)
- ASTM A106
- ASTM D2513
- ASTM B88
Correct answer: ASTM A53
ASTM A53 covers seamless and welded black and hot-dipped galvanized steel pipe used in gas distribution systems.
Question 6: When selecting pipe material for a gas system in seismic zone D, which material has a significant advantage?
- Cast iron
- Rigid black steel
- CSST (Correct answer)
- Galvanized steel
Correct answer: CSST
CSST's flexible corrugated design allows it to absorb seismic movement without cracking or breaking, making it advantageous in high-seismic zones.
Question 7: What is the maximum operating pressure for ASTM D2513 PE pipe in a residential gas distribution system?
- 0.5 psi
- 2 psi
- 5 psi (Correct answer)
- 60 psi
Correct answer: 5 psi
PE pipe meeting ASTM D2513 is rated for a maximum of 5 psi operating pressure in residential gas distribution.
GPT Material Selection & Properties 2
Which pipe material is prohibited for use with LP-gas service in most US codes?