ccps-2001-checker

CCPS (2001) — Layer of Protection Analysis: Simplified Process Risk Assessment

Purpose

This skill provides reference material for CCPS (2001) Layer of Protection Analysis: Simplified Process Risk Assessment, published by the Center for Chemical Process Safety of the American Institute of Chemical Engineers. It ensures accurate technical information when producing LOPA reports, risk assessments, IPL qualification evaluations, SIL determination studies, and process safety analyses.

Critical Rules

1. Only cite data that appears in the section files. Never fabricate or assume frequency values, PFD ranges, risk tolerance criteria, or screening values.
2. Preserve numerical accuracy. All frequencies, PFDs, screening values, and equation parameters must be quoted exactly as they appear in the reference data.
3. Use conservative, factual language when describing LOPA methodology and risk decisions. Avoid interpretation or extrapolation beyond what the source states.
4. Always use Australian English spelling (e.g. analyse, minimise, behaviour, organisation, colour, centre).
5. If a provision cannot be located in these files, state that the specific data should be verified against the original CCPS (2001) publication.
6. Table 5.2 clarification. Table 5.2 in CCPS (2001) is titled "Various Ways to Express Failure Rates" and shows notation formats (decimal, scientific, exponent, integer logarithm). It does NOT contain IPL PFD data. IPL PFD data is found in Tables 6.3, 6.4, and 6.5.
7. Screening values are conservative. CCPS screening values represent the upper (more conservative) end of the range, intended for initial LOPA assessments. Site-specific data may justify different values.

Section Index

Read the relevant section file(s) based on the technical domain of the query:

File	Coverage	When to Read
sections/s01-overview-methodology.md	Chapter 2: LOPA overview, 5-step methodology, when to use LOPA, cause-consequence pairs, Figure 2.1 layers of defence	Any query about LOPA process, methodology steps, when LOPA is appropriate, relationship to PHA/HAZOP
sections/s02-consequences-severity.md	Chapter 3: Consequence categorisation (Tables 3.1, 3.2), four methods for consequence evaluation, severity classification	Consequence assessment, severity categories, category definitions, methods for evaluating consequences
sections/s03-initiating-events.md	Chapter 5: Initiating event frequencies (Table 5.1 complete), Table 5.2 notation formats, enabling events and conditions, types of initiating events	Initiating event frequency lookup, equipment failure rates, BPCS failure, operator error rates, enabling events
sections/s04-ipl-identification.md	Chapter 6: IPL definition, 3 qualification rules, IPL characteristics, Table 6.1 non-IPL safeguards, Table 6.2 dependent failure causes, Table 6.3 passive IPLs, Table 6.4 active IPLs, Table 6.5 human action IPLs, SIL 1–4 PFD ranges, preventive vs mitigation IPLs, BPCS Approach A/B	IPL qualification, PFD lookup, safeguard assessment, SIL determination, independence evaluation, common cause analysis
sections/s05-scenario-frequency.md	Chapter 7: Equation 7-1, mitigated scenario frequency calculation, conditional modifiers (P_ignition, P_personnel, P_fatality), worked examples	Frequency calculations, Equation 7-1, conditional modifiers, mitigated frequency determination
sections/s06-risk-decisions.md	Chapter 8: Risk decision methods (matrix, numerical criteria, IPL credits, expert judgment, cost–benefit), Table 8.1 risk matrix, Table 8.2 IPL credit requirements, Equation 8-1 cumulative risk, LOPA summary sheet format (Tables 8.3, 8.4), Section 8.9 cautions	Risk decision making, risk matrix lookup, IPL credit determination, tolerable risk comparison, LOPA documentation
sections/s07-risk-tolerance-criteria.md	Appendix E: Industry risk tolerance criteria data, typical LOPA criteria (per scenario and cumulative), company examples (ICI, Rohm and Haas), Notes 1–3	Risk tolerance criteria, maximum tolerable risk, negligible risk, workforce vs public criteria, per-scenario vs cumulative
sections/s08-high-demand-mode.md	Appendix F: High demand mode calculations, Equations F-1 and F-2, low demand vs high demand transition, worked examples	High initiating event frequency scenarios, demand rate exceeding test frequency, high demand mode equations
sections/s09-glossary-references.md	Glossary of Terms, SIL table (demand mode), key definitions (BPCS, CPQRA, IPL, LOPA, PFD, PHA, SIF, SIL, SIS), References list	Terminology definitions, SIL/PFD relationship table, citation verification, reference list

Workflow

1. Identify the technical domain from the user's query (methodology, frequencies, IPL PFDs, risk decisions, risk tolerance, calculations)
2. Read the relevant section file(s) — read only what is needed, not all files
3. Cite data accurately from the extracted text (e.g. "Per CCPS (2001), Table 5.1...")
4. Cross-reference between sections where appropriate (e.g. IPL PFDs from Section 4 used in calculations from Section 5)
5. Flag any gaps — if additional information from other standards (e.g. IEC 61511, IEC 61508) is required, note this clearly

Common Query Routing

Query Topic	Primary Section(s)	Coverage
LOPA methodology and process	s01	5-step process, when to use, cause-consequence pairs
Consequence severity categories	s02	Tables 3.1, 3.2, four evaluation methods
Initiating event frequency values	s03	Table 5.1 complete (20+ event types with ranges and screening values)
Equipment failure rates	s03	Pressure vessels, piping, tanks, gaskets, pumps, cooling water
BPCS instrument loop failure	s03	Table 5.1 BPCS entries
Human error / operator failure rates	s03, s04	Table 5.1 operator failure, Table 6.5 human action IPLs
IPL qualification rules	s04	Three rules: effective, independent, auditable
What is NOT an IPL	s04	Table 6.1 (14 safeguard types that usually do not qualify)
Common cause / dependent failure	s04	Table 6.2 causes of dependent failure
Passive IPL PFD values	s04	Table 6.3 (dike, drainage, open vent, fireproofing, blast wall, ISD, arrestors)
Active IPL PFD values	s04	Table 6.4 (relief valve, rupture disc, BPCS, SIL 1–4)
Human action IPL PFD values	s04	Table 6.5 (three response time categories)
SIL / PFD relationship	s04, s09	SIL 1–4 PFD ranges in Table 6.4 and Glossary
Mitigated frequency calculation	s05	Equation 7-1, conditional modifiers
Risk matrix interpretation	s06	Table 8.1 with action zones
IPL credit requirements	s06	Table 8.2 credit requirements by consequence category
Risk tolerance criteria	s07	Appendix E typical LOPA criteria, industry examples
High demand mode	s08	Equations F-1, F-2, transition point, worked examples
LOPA summary sheet format	s06	Tables 8.3, 8.4 complete worked examples
Glossary / definitions	s09	All key terms with CCPS definitions

Version Information

• Publication: CCPS (2001), Layer of Protection Analysis: Simplified Process Risk Assessment
• Publisher: Center for Chemical Process Safety, American Institute of Chemical Engineers, New York
• ISBN: 0-8169-0811-7

Note: This skill covers CCPS (2001) only. For IEC functional safety standards, refer to IEC 61508 and IEC 61511. For Australian WHS legislation context, use the safetysure-whs-legislation plugin (whs-act-checker and whs-regulation-checker skills).