API 510 Safety Procedures 2 — Questions and Answers
Question 1: According to API 510, what must be done before any inspector enters a pressure vessel for internal inspection?
- The vessel must be isolated, depressurized, purged, and ventilated to ensure a safe atmosphere (Correct answer)
- The vessel only needs to be cooled to ambient temperature before entry
- Reducing internal pressure to 15 psig is sufficient for safe entry
- The inspector may enter with supplied-air respirator without additional preparation
Correct answer: The vessel must be isolated, depressurized, purged, and ventilated to ensure a safe atmosphere
API 510 requires vessels to be fully isolated, depressurized, purged of hazardous contents, and ventilated to safe atmospheric conditions before any personnel entry.
Question 2: Which lockout/tagout (LOTO) requirement applies to pressure vessel inspection per OSHA 29 CFR 1910.147 referenced in API 510 work?
- All energy sources must be isolated and locked out before inspection begins (Correct answer)
- Tagging alone is acceptable when the vessel is at low pressure
- LOTO is only required for vessels above 150 psig operating pressure
- Only electrical energy sources require lockout; steam lines can remain active
Correct answer: All energy sources must be isolated and locked out before inspection begins
OSHA 29 CFR 1910.147 requires all hazardous energy sources—pressure, thermal, electrical, chemical—to be isolated and locked out before inspection.
Question 3: When performing hot work near a pressure vessel that has contained flammable material, what document is typically required before work begins?
- A hot work permit signed by authorized personnel (Correct answer)
- Only verbal authorization from the shift supervisor
- A maintenance work order referencing the vessel number
- A confined space entry permit is sufficient for all hot work
Correct answer: A hot work permit signed by authorized personnel
Hot work permits are required before any spark- or flame-producing work near flammables, and must be authorized by responsible facility personnel.
Question 4: An API 510 inspector identifies hydrogen sulfide (H₂S) in a vessel's previous service. What safety requirement takes priority before internal inspection?
- Atmospheric testing must confirm H₂S levels are within safe limits before entry (Correct answer)
- The inspector should wear a gas mask rated for particulates only
- H₂S dissipates naturally within 30 minutes of opening a manway
- Entry is acceptable if H₂S service was more than 6 months ago
Correct answer: Atmospheric testing must confirm H₂S levels are within safe limits before entry
H₂S is immediately dangerous to life and health (IDLH) at 100 ppm; atmospheric testing must confirm safe levels before any entry.
Question 5: What is the minimum number of people required for a safe confined space entry inspection of a pressure vessel per industry safety standards?
- At least two: an entrant and an attendant stationed outside (Correct answer)
- One person is acceptable if equipped with a personal gas monitor
- Three people: two inside and one outside
- No minimum is specified; it depends on vessel size only
Correct answer: At least two: an entrant and an attendant stationed outside
OSHA permit-required confined space regulations mandate at least one entrant and one trained attendant who remains outside to monitor and respond to emergencies.
Question 6: When scaffolding is erected inside a large pressure vessel for inspection, what API 510 safety concern must be addressed regarding the scaffold materials?
- Scaffold materials must not introduce spark or ignition hazards if flammable residues remain (Correct answer)
- Steel scaffolding is always prohibited inside any pressure vessel
- Scaffolding inside vessels must be rated for twice the inspector's body weight only
- No special material restrictions apply if the vessel has been washed with water
Correct answer: Scaffold materials must not introduce spark or ignition hazards if flammable residues remain
Scaffold materials must be selected to avoid ignition of any residual flammables, and non-sparking tools and materials may be required in hazardous environments.
Question 7: Which of the following best describes the purpose of a job safety analysis (JSA) prior to pressure vessel inspection?
- To systematically identify hazards associated with each inspection task and establish controls (Correct answer)
- To estimate the total labor hours needed to complete the inspection
- To document the inspector's qualifications and certifications on file
- To fulfill the API 510 thickness measurement recordkeeping requirement
Correct answer: To systematically identify hazards associated with each inspection task and establish controls
A JSA breaks each inspection task into steps, identifies potential hazards at each step, and establishes hazard controls before work begins.
API 510 Safety Procedures 2
According to API 510, what must be done before any inspector enters a pressure vessel for internal inspection?