API Quality Control and Materials 3 — Questions and Answers
Question 1: What is the significance of the 'P-number' system used in ASME Section IX and referenced by API welding standards?
- It identifies pipeline pressure ratings
- It groups base metals with similar weldability to reduce required procedure qualifications (Correct answer)
- It assigns priority to inspection tasks
- It designates pipe schedule numbers
Correct answer: It groups base metals with similar weldability to reduce required procedure qualifications
P-numbers group base metals by chemical composition and mechanical properties so that one WPS can qualify welding of all metals in the same group.
Question 2: A quality inspector observes laminations in a steel plate during ultrasonic examination. Laminations are best described as:
- Cracks perpendicular to the plate surface
- Planar discontinuities parallel to the plate surface caused during rolling (Correct answer)
- Surface pits from corrosion
- Weld slag inclusions
Correct answer: Planar discontinuities parallel to the plate surface caused during rolling
Laminations are internal, planar defects parallel to the plate surface that originate from non-metallic inclusions elongated during the rolling process.
Question 3: Per API quality requirements, how often must calibration of measuring and test equipment (M&TE) be verified?
- Only when purchased
- At intervals established in the quality program to maintain accuracy (Correct answer)
- Every 10 years
- Only after suspected damage
Correct answer: At intervals established in the quality program to maintain accuracy
API quality systems require M&TE to be calibrated at defined intervals traceable to national standards to ensure measurement accuracy.
Question 4: What type of weld discontinuity is characterized by incomplete fusion between the weld metal and the base metal at the root of the joint?
- Porosity
- Undercut
- Lack of root fusion (incomplete penetration) (Correct answer)
- Overlap
Correct answer: Lack of root fusion (incomplete penetration)
Incomplete root penetration or lack of root fusion occurs when the weld metal does not fully fuse with the base metal at the root, creating a planar defect.
Question 5: In API storage tank construction (API 650), what is the purpose of a radiographic examination of weld seams?
- To measure weld bead width
- To detect internal discontinuities such as porosity, slag, and cracks (Correct answer)
- To verify surface finish quality
- To measure heat input
Correct answer: To detect internal discontinuities such as porosity, slag, and cracks
Radiographic testing (RT) uses X-rays or gamma rays to reveal internal weld defects on film or digital media for evaluation.
Question 6: Which API document provides recommended practice for inspection of in-service pressure vessels?
- API 510 (Correct answer)
- API 570
- API 653
- API 580
Correct answer: API 510
API 510 covers inspection, repair, alteration, and rerating of in-service pressure vessels in the petroleum and chemical industries.
Question 7: When conducting a hydrostatic pressure test on a pipeline, the test pressure is typically set at what ratio relative to the maximum allowable operating pressure (MAOP)?
- Equal to MAOP
- 1.1 to 1.5 times MAOP, depending on the applicable code (Correct answer)
- 0.5 times MAOP
- 2.0 times MAOP always
Correct answer: 1.1 to 1.5 times MAOP, depending on the applicable code
Most pipeline codes require hydrostatic test pressure between 1.1× and 1.5× MAOP, with the specific multiplier depending on design code and location class.
API Quality Control and Materials 3
What is the significance of the 'P-number' system used in ASME Section IX and referenced by API welding standards?