← All standards & equipment
API

API 581

Risk-Based Inspection Methodology

Issuing body
API
Latest edition
3rd Edition (2016, A1 2019, A2 2020)
Region
USA, Global
Equipment items
2

Scope

Quantitative RBI calculation methodology — POF, COF, risk ranking, inspection planning.

Key requirements (7)

  • Quantitative RBI methodology — damage factor approach.
  • Damage factor (DF) by mechanism: thinning, SCC, HTHA, brittle fracture, fatigue, etc.
  • Generic failure frequency (gff) baseline: typically 4×10⁻⁵/yr leak frequency.
  • Adjusted POF = gff × DF × FMS (management systems factor).
  • COF: area-based (ft²) for flammable, dispersion modeling for toxic.
  • Inspection effectiveness: A (highly effective) to E (no effectiveness) — degrades DF.
  • Re-inspection date driven by acceptable risk threshold (often 5×10⁻⁴/yr).

Related standards (2)

Applied to 2 equipment items