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Inspection & Process Safety

HAZOP / LOPA Study

Process hazard analysis (HAZOP) and Layer of Protection Analysis (LOPA).

Category
Inspection & Process Safety
Subcategory
Process Safety
Applicable standards
3
Issuing bodies
2

Description

Process hazard analysis (HAZOP) and Layer of Protection Analysis (LOPA).

Applicable Standards (3)

API — 1 standard

API RP 754 Process Safety Performance Indicators for the Refining and Petrochemical Industries
Edition: 2nd Edition (2021) Region: USA, Global
Tier 1–4 leading and lagging process safety indicators (PSE, LOPC, etc.).

IEC — 2 standards

IEC 61882 Hazard and operability studies (HAZOP studies) — Application guide
Edition: 2016 Region: Global
HAZOP study application — guide words, methodology, recording.
IEC 61511 Functional safety — Safety instrumented systems for the process industry sector
Edition: 2016 + A1 2017 Region: Global
SIS lifecycle, SIL, application of IEC 61508 in process industries.
Key requirements (9)
  • Safety Instrumented Systems for the process industry.
  • Safety lifecycle: H&RA → SIL allocation → design → operate → modify → decommission.
  • SIL levels (by PFDavg): SIL 1 (10⁻²–10⁻¹), SIL 2 (10⁻³–10⁻²), SIL 3 (10⁻⁴–10⁻³), SIL 4 (10⁻⁵–10⁻⁴).
  • Risk reduction factor RRF = 1/PFDavg.
  • SIL determination: LOPA, risk graph, risk matrix.
  • Architectures: 1oo1, 1oo2, 2oo3, 2oo4 — voting + redundancy for SIL.
  • Proof test interval (PTI) drives PFDavg: PFDavg ≈ λDU·PTI/2 for 1oo1.
  • MooN voting requires hardware fault tolerance (HFT) per Tables 3/4.
  • Cybersecurity: refer to IEC 62443 for SIS.