API 510 Code Requirements 4 — Questions and Answers
Question 1: API 510 states that the authorized pressure vessel inspector must be certified by:
- The American Society of Mechanical Engineers (ASME)
- The National Board of Boiler and Pressure Vessel Inspectors or an equivalent jurisdictional authority (Correct answer)
- The vessel owner's internal safety department
- The American Petroleum Institute directly
Correct answer: The National Board of Boiler and Pressure Vessel Inspectors or an equivalent jurisdictional authority
The API 510 authorized inspector must be certified by the National Board or a recognized jurisdictional authority, and must hold a valid API 510 certificate.
Question 2: Under API 510, which of the following is the correct approach when actual corrosion rates differ significantly from previously assumed rates?
- Continue using the original assumed rate until the next scheduled inspection
- Recalculate remaining life and adjust the inspection interval accordingly (Correct answer)
- Immediately take the vessel out of service
- File a variance with the jurisdiction and continue operating
Correct answer: Recalculate remaining life and adjust the inspection interval accordingly
When actual corrosion rates differ from previous estimates, the remaining life calculation must be updated and the inspection interval revised to reflect current conditions.
Question 3: According to API 510, the maximum allowable working pressure (MAWP) of a vessel is based on:
- The operating pressure at the time of the most recent inspection
- The weakest pressure-containing element calculated per the applicable construction code (Correct answer)
- The original design pressure stamped on the nameplate only
- The hydrotest pressure divided by the safety factor of 1.3
Correct answer: The weakest pressure-containing element calculated per the applicable construction code
MAWP is determined by the weakest pressure-containing component of the vessel, calculated per the applicable code at the governing conditions.
Question 4: When API 510 refers to 'pitting' as a damage mechanism, how should an inspector evaluate scattered pitting for fitness-for-service?
- Average the pit depths over the entire vessel surface
- Use the remaining thickness at the deepest pit location as the governing thickness
- Ignore pitting unless it covers more than 50% of the surface area
- Apply API 510 Annex B pitting charts or an equivalent FFS methodology (Correct answer)
Correct answer: Apply API 510 Annex B pitting charts or an equivalent FFS methodology
Scattered pitting should be evaluated using the pitting charts in API 510 Annex B or an equivalent FFS method, considering pit density and remaining ligament thickness.
Question 5: API 510 requires that inspection results and thickness data be retained for how long?
- 5 years after the inspection date
- Until the vessel is retired or transferred to a new owner (Correct answer)
- 10 years after the inspection date
- The life of the equipment plus 3 years
Correct answer: Until the vessel is retired or transferred to a new owner
API 510 requires that inspection records be retained for the life of the vessel; when ownership transfers, records must accompany the vessel.
Question 6: Under API 510, if a repair organization lacks the applicable ASME code stamp, they may perform pressure vessel repairs only if:
- They are approved by the vessel owner and the work is documented
- They hold a National Board 'R' stamp repair certificate (Correct answer)
- The repair is cosmetic and does not involve pressure-containing welds
- They subcontract the welding to a code-stamped organization
Correct answer: They hold a National Board 'R' stamp repair certificate
Organizations performing pressure vessel repairs must hold a National Board 'R' stamp or equivalent authorization recognized by the jurisdiction.
Question 7: According to API 510, which inspection method is specifically recommended for detecting hydrogen-induced cracking (HIC) in wet H₂S service?
- Visual inspection only
- Radiographic testing (RT) using film
- Ultrasonic testing (UT) using shear wave or phased array techniques (Correct answer)
- Dye penetrant testing (PT) of the external surface
Correct answer: Ultrasonic testing (UT) using shear wave or phased array techniques
Shear wave UT or phased array UT is recommended for detecting HIC and stepwise cracking because these techniques can identify planar flaws parallel to the vessel wall.
API 510 Code Requirements 4
API 510 states that the authorized pressure vessel inspector must be certified by: