API 510 Code Requirements 3 — Questions and Answers
Question 1: When API 510 refers to an 'alteration' to a pressure vessel, which of the following best describes this term?
- Any change to the inspection interval documented in the vessel records
- A physical change to a pressure-containing component that affects its design (Correct answer)
- Replacement of a nozzle with an identical nozzle of the same material and rating
- Repainting or recoating the external surface of the vessel
Correct answer: A physical change to a pressure-containing component that affects its design
An alteration is a physical change to pressure-containing parts that affects the design conditions or the pressure-containing capability of the vessel.
Question 2: According to API 510, what is the primary purpose of the corrosion rate established from inspection data?
- To classify the vessel into a risk category
- To set the next inspection interval and predict remaining service life (Correct answer)
- To determine whether the vessel needs replacement immediately
- To calculate the hydrotest pressure for the next scheduled test
Correct answer: To set the next inspection interval and predict remaining service life
The corrosion rate is used to calculate remaining life and to set the next inspection interval based on when the vessel will reach minimum required thickness.
Question 3: Under API 510, a vessel owner wants to use a higher allowable stress than the original code of construction allowed. This would constitute:
- A repair requiring only the inspector's approval
- A rerating of the vessel requiring engineering review and documentation (Correct answer)
- A routine maintenance activity not requiring documentation
- An alteration only if the MAWP is changed
Correct answer: A rerating of the vessel requiring engineering review and documentation
Using higher allowable stress to increase MAWP constitutes a rerating that requires engineering calculations, documentation, and review per API 510.
Question 4: API 510 specifies that weld repairs on pressure vessels must be performed using:
- Any qualified welding procedure, regardless of original code requirements
- Procedures and welders qualified in accordance with the applicable construction code (Correct answer)
- Only the original fabricator's procedures
- ASME Section IX procedures approved by the jurisdiction only
Correct answer: Procedures and welders qualified in accordance with the applicable construction code
Weld repairs must use procedures and welders qualified per the applicable construction code (typically ASME Section VIII and Section IX).
Question 5: According to API 510, what post-weld heat treatment (PWHT) requirement applies to weld repairs on vessels that required PWHT during original fabrication?
- PWHT is never required for repairs
- PWHT is required unless an approved alternative procedure is used (Correct answer)
- PWHT is required only if the repair weld is longer than 6 inches
- PWHT is optional at the inspector's discretion
Correct answer: PWHT is required unless an approved alternative procedure is used
Vessels that required PWHT during fabrication generally require PWHT after repair welding unless an approved alternative (such as temper bead welding) is documented and approved.
Question 6: Under API 510, the term 'fitness-for-service' (FFS) assessment is used to:
- Replace the standard inspection program entirely
- Evaluate whether a vessel with a flaw or damage can continue in service safely (Correct answer)
- Certify that a vessel meets new construction code requirements
- Establish the original MAWP of a vessel without documentation
Correct answer: Evaluate whether a vessel with a flaw or damage can continue in service safely
FFS assessment evaluates whether a vessel containing flaws, damage, or degradation can continue to operate safely under defined conditions.
Question 7: When API 510 requires a pressure test after a repair or alteration, the default test is a:
- Pneumatic test at 1.1 times MAWP
- Hydrostatic test at 1.3 times MAWP (or per the applicable construction code) (Correct answer)
- Vacuum test at full negative pressure
- Leak test at operating pressure only
Correct answer: Hydrostatic test at 1.3 times MAWP (or per the applicable construction code)
The default pressure test after repair or alteration is a hydrostatic test at the pressure specified by the applicable construction code, typically 1.3 times MAWP for ASME vessels.
API 510 Code Requirements 3
When API 510 refers to an 'alteration' to a pressure vessel, which of the following best describes this term?