Steamfitter Technical Standards and Specifications 3 — Questions and Answers
Question 1: What is the maximum allowable working pressure (MAWP) concept used to determine in piping design?
- The lowest pressure at which a system must operate
- The highest pressure a system can safely sustain during normal operation (Correct answer)
- The test pressure applied during hydrostatic testing
- The pressure at which safety valves must be set
Correct answer: The highest pressure a system can safely sustain during normal operation
MAWP is the maximum gauge pressure permissible at the top of a completed vessel or piping system in its normal operating position at the designated temperature.
Question 2: According to ASME B31.1, what hydrostatic test pressure is required for new piping systems (as a multiple of design pressure)?
- 1.25 times the design pressure
- 1.5 times the design pressure (Correct answer)
- 1.1 times the design pressure
- 2.0 times the design pressure
Correct answer: 1.5 times the design pressure
ASME B31.1 requires hydrostatic leak testing at 1.5 times the design pressure to verify integrity of new power piping systems.
Question 3: Which AWS standard governs the qualification of welding procedures and welders for structural welding?
- AWS D1.1 (Correct answer)
- AWS D1.6
- ASME Section IX
- AWS D10.12
Correct answer: AWS D1.1
AWS D1.1 Structural Welding Code—Steel governs the qualification of welding procedures and welders for structural steel applications.
Question 4: What is the purpose of a Procedure Qualification Record (PQR) in piping welding?
- To document a welder's personal certifications and training history
- To record the actual test results that support a Welding Procedure Specification (Correct answer)
- To list approved filler materials for a given base metal
- To schedule weld inspection intervals on a project
Correct answer: To record the actual test results that support a Welding Procedure Specification
A PQR documents the actual variables used and test results obtained when qualifying a Welding Procedure Specification (WPS), providing evidence the procedure produces sound welds.
Question 5: Under ASME B31.1, what is the definition of 'nominal pipe size' (NPS)?
- The actual outside diameter of the pipe in inches
- A dimensionless designator correlating to pipe outside diameter but not equal to it above NPS 12 (Correct answer)
- The inside diameter of the pipe for all sizes
- The wall thickness designation for schedule 40 pipe
Correct answer: A dimensionless designator correlating to pipe outside diameter but not equal to it above NPS 12
NPS is a dimensionless designator used in the US piping system; for NPS 14 and larger, the NPS number equals the actual outside diameter in inches, but for smaller sizes it does not.
Question 6: Which ASTM specification covers austenitic stainless steel pipe commonly used in high-temperature and corrosive service?
- ASTM A53
- ASTM A106
- ASTM A312 (Correct answer)
- ASTM A335
Correct answer: ASTM A312
ASTM A312 covers seamless, straight-seam welded, and heavily cold worked welded austenitic stainless steel pipe for high-temperature and general corrosive service.
Question 7: What does the term 'joint efficiency' (E) account for in pressure piping design calculations?
- The friction loss across a pipe joint
- The reduction in allowable stress due to the type and quality of the pipe joint or weld (Correct answer)
- The thermal expansion capacity of a mechanical coupling
- The percentage of flow lost through a leaking joint
Correct answer: The reduction in allowable stress due to the type and quality of the pipe joint or weld
Joint efficiency is a factor (0 to 1.0) that reduces allowable stress to account for the weakening effect of a weld seam or mechanical joint relative to seamless pipe.
Steamfitter Technical Standards and Specifications 3
What is the maximum allowable working pressure (MAWP) concept used to determine in piping design?