chemical-process-safety-method

# Chemical Process Safety Method ## Establish the review basis Freeze the facility, business and jurisdictional context, unit and process boundary, node or equipment scope, chemical identity and physical state, inventory and unit basis, normal/startup/shutdown/temporary/abnormal operating modes, process-flow and piping-and-instrumentation drawing revisions, process safety information cutoff, change and incident cutoff, applicable owner standards, requested decision and accountable reviewers. Record temperature, pressure, flow, composition and inventory only with units, measurement point, condition and source. A drawing number without revision or an operating limit without its approved basis is not current evidence. ## Process safety information branch Build a traceable inventory of chemical-hazard information, process technology and equipment information. For chemicals, retain identity, composition, incompatibility evidence, toxicity/reactivity/flammability properties and source date; never infer compatibility. For technology, link process chemistry, material and energy balance when supplied, safe upper/lower limits, consequences of deviation and safety-system design basis. For equipment, link materials of construction, design codes, relief and ventilation basis, electrical classification, alarms, interlocks, detection, suppression and inspection programs. Record recognized-and-generally-accepted-good-engineering-practice claims exactly as supplied and route adequacy to engineers. ## Hazard analysis branch Select the approved Process Hazard Analysis method for the stated lifecycle and complexity; do not choose one merely because a template exists. In a Hazard and Operability Study, freeze node, design intent, parameter and guideword, then trace deviation to credible initiating cause, consequence, affected people/environment/assets, existing preventive and mitigative safeguards, human factors, facility siting, detection, uncertainty and recommendation. Preserve What-If, Checklist, Failure Mode and Effects Analysis or Fault Tree records under their actual method names. Do not merge distinct scenarios because they share a consequence. Layer of Protection Analysis is conditional. Perform arithmetic only when the authorized source supplies initiating-event frequency, enabling and conditional modifiers, consequence criterion, risk tolerance, Independent Protection Layer definition, independence/auditability/specificity evidence and probability of failure on demand. Show every factor and unit. Prevent double-counting one device, action or common utility across safeguards. A safeguard is not an IPL merely because it appears in a HAZOP. Missing independence, testing or failure data is an open question, not a default credit. The method never declares tolerable risk. ## Integrity, change and readiness branch For mechanical integrity, bind each pressure vessel, piping circuit, relief device, rotating asset, storage system, control or emergency device to stable equipment identity, service, damage mechanism as supplied, inspection/test method, interval basis, last result, next due date, deficiency, temporary repair or deferral approval evidence. Do not calculate remaining life, fitness for service, relief capacity or inspection interval unless an authorized engineer provides the method and inputs. For Management of Change, distinguish replacement in kind from change using the approved local definition. Trace description, purpose, technical basis, safety and health impact, affected procedures/drawings/calculations/alarms/interlocks, temporary-change expiry, training and communication, authorization requirements and closeout evidence. Pre-Startup Safety Review evidence must link construction/design conformance, procedures, training, PHA recommendation disposition and readiness prerequisites. The pack may identify a missing prerequisite but cannot authorize startup. ## Incident and barrier learning branch Freeze event identity, time zone, process state, evidence cutoff and investigation authority. Separate direct observations, timeline, causal hypotheses, investigation findings and authorized conclusions. Map each scenario to barrier objective, demanded function, evidence of availability, actual response, degradation or failure, common-cause dependency and owner. Trace each recommendation to rationale, accountable owner, due date, MOC or procedure dependency, completion evidence and effectiveness/revalidation evidence. Administrative closure or a changed document does not prove effectiveness. ## Join and decision discipline Use exactly the five assets in this Skill. Every row needs stable ID, quantity and unit/basis where relevant, source URI or controlled-record identifier, source version, observation/effective date, extraction date, owner, reviewer, applicability, uncertainty, status, decision-not-made field and stop condition. The join links PSI gaps to scenarios, scenarios to barriers, barriers to integrity evidence, changes to affected scenarios and incidents to revalidation. Preserve incompatible revisions and competing values rather than averaging them. A green status requires actual qualified disposition evidence. ## Unknown and stop rules Stop when process/node boundaries, chemical identity, units, operating mode, drawing revision, equipment identity, event period, safeguard independence, inspection method, change authority or source lineage is absent or contradictory. Stop when information may be trade-secret, security-sensitive or personally identifiable and access is not authorized. Do not fill an unknown with typical industry values, assume a device is available, count an action twice, infer causal closure or transform a recommendation into an instruction. ## Authority and qualified review This method does not set operating envelopes, alarm or trip setpoints, bypasses, relief or ventilation design, Safety Instrumented Function integrity, chemical compatibility, inspection interval, fitness for service or emergency action. It does not credit an Independent Protection Layer, accept residual risk, approve a Management of Change, Pre-Startup Safety Review, startup, shutdown, permit or temporary operation, issue a public warning, certify OSHA/EPA/local compliance or provide legal advice. Route decisions to authorized process-safety and process engineers, operations, mechanical integrity, inspection, materials, instrument/control, electrical, relief, human-factors, environmental-health-safety, emergency, PHA/LOPA facilitators, site leadership, Authority Having Jurisdiction and legal counsel. Read `references/source-provenance.md` before modifying this clean-room method. No rejected remote Skill text, template, code or asset was copied.