Safety Study Types
HAZAN, What-If, FMEA Overview
Process plants conduct multiple safety study types across the project lifecycle: HAZID (hazard identification), HAZOP (deviation analysis), HAZAN (consequence analysis), What-If (open-ended hazard discovery), LOPA (layer of protection quantification), and FMEA (failure mode and effects analysis). Each study type serves a specific safety lifecycle stage; greenfield projects typically conduct HAZID, HAZOP, LOPA, and FMEA in sequence.
What is Safety Study Types in full?
Safety study types in EPC projects cover the safety lifecycle from early-stage hazard identification through detailed quantification. HAZID (Hazard Identification Study) is the early-stage open hazard search during conceptual design. HAZOP (Hazard and Operability Study) is the structured node-by-node deviation analysis using P&IDs. HAZAN (Hazard Analysis) is the consequence and frequency quantification. What-If is the open-ended hazard discussion using engineering judgement. LOPA (Layer of Protection Analysis) is the semi-quantitative SIL classification method. FMEA (Failure Mode and Effects Analysis) is the systematic failure mode review used in equipment and reliability engineering. Each study type serves a specific safety lifecycle stage.
What are the key specifications for Safety Study Types?
- HAZID
- Guideword-based hazard identification at conceptual / early FEED stage; reference ISO 17776
- HAZOP
- Node-by-node deviation analysis on frozen P&IDs at detailed design; reference IEC 61882
- What-If / Checklist
- Open-ended screening review using engineering judgement; used for modifications and low-complexity units
- LOPA
- Semi-quantitative layer of protection analysis for SIL target selection after HAZOP; reference IEC 61511 and CCPS guidelines
- SIL Assessment
- Safety Integrity Level classification and verification of safety instrumented functions; reference IEC 61508 / IEC 61511
- FMEA
- Systematic failure mode and effects review for equipment and reliability engineering; reference IEC 60812
- QRA / HAZAN
- Quantitative consequence and frequency modelling for siting and risk acceptance decisions
- Typical Greenfield Sequence
- HAZID at FEED, HAZOP at detailed design, LOPA / SIL after HAZOP, FMEA on critical equipment
- Indian Regulatory Overlay
- OISD 118 layout compliance and PNGRB / PESO requirements reference HAZOP closure evidence
What context and detail applies to Safety Study Types?
Safety study lifecycle
Typical safety lifecycle in greenfield EPC: HAZID at conceptual / FEED stage (siting and layout decisions), HAZOP at detailed design (P&ID-driven deviation analysis), LOPA following HAZOP (SIL classification), FMEA on critical equipment (reliability and failure mode review), Pre-Startup Safety Review (PSSR) at mechanical completion, Operations safety reviews (incident-driven). Each study type produces structured findings that flow into the project safety lifecycle deliverables.
HAZOP and LOPA: how the two studies connect
HAZOP and LOPA are run as a pair on most EPC projects, which is why engineers search for them together. The HAZOP comes first: node-by-node deviation analysis on frozen P&IDs produces a list of hazardous scenarios, each with cause, consequence, and the safeguards already in the design. LOPA then takes the subset of HAZOP scenarios with high severity (typically those where the team could not agree that existing safeguards were adequate) and quantifies them: initiating event frequency, the probability of failure on demand of each independent protection layer, and the residual risk against the corporate tolerable-risk target. Where the gap is too large, LOPA sets the SIL target for a new safety instrumented function. The practical consequences: the HAZOP register must carry a 'LOPA required' flag per scenario, the LOPA worksheet must reference the HAZOP node and deviation it came from, and the two registers must be revalidated together when a P&ID revision changes a safeguard. On Indian projects, OISD 118 auditors ask for this traceability from HAZOP scenario to LOPA scenario to SIL target. Templates for both registers are available: the HAZOP register template and the LOPA worksheet template, and the detail pages for HAZID, LOPA, and SIL cover each study on its own.
HAZAN and What-If
HAZAN (Hazard Analysis) is a structured consequence and frequency quantification for specific hazard scenarios. HAZAN may use Quantitative Risk Assessment (QRA) methods to compute consequence in deaths, monetary loss, or environmental damage. What-If is the open-ended hazard discussion using engineering judgement and structured 'what if?' questions. What-If is typically used at early design stages or for incident investigation; HAZAN is used for specific high-criticality hazards requiring quantitative assessment.
FMEA in process industries
FMEA (Failure Mode and Effects Analysis) is the systematic review of failure modes per component or equipment item. FMEA outputs a structured table of failure modes, effects, severity ratings, detection ratings, and risk priority numbers (RPN). FMEA is widely used in automotive and aerospace per AIAG / VDA standards; in process industries FMEA is used for critical rotating equipment reliability engineering and safety system design.
How is Safety Study Types used in EPC projects?
- 01
Greenfield refinery, petrochemical plant, fertiliser plant, and gas processing facility EPC projects conduct HAZID, HAZOP, LOPA, and FMEA across the safety lifecycle.
- 02
Brownfield revamp projects conduct HAZID and HAZOP for modification scope; existing safety studies remain valid for unchanged scope.
- 03
Indian PSU greenfield projects conduct safety studies per OISD framework requirements alongside ASME / IEC standards.
- 04
Operations safety reviews during operating phase use What-If sessions and HAZOP revalidation cycles to verify continued safety compliance.
How does Pathnovo handle Safety Study Types?
Pathnovo's HAZOP Safety Intelligence pillar digitises HAZOP, HAZID, LOPA, and What-If studies from PDF reports into structured queryable registers. Each study type maps to specific lifecycle stages and supports OISD audit-readiness, SIS lifecycle deliverables, and ongoing operational safety reviews.
Frequently Asked Questions
What safety study types are used in EPC?
Common safety study types: HAZID (hazard identification), HAZOP (deviation analysis), HAZAN (consequence quantification), What-If (open-ended discovery), LOPA (layer of protection quantification), FMEA (failure mode analysis). Each serves a specific safety lifecycle stage; greenfield projects typically conduct HAZID, HAZOP, LOPA, and FMEA in sequence.
What is the difference between HAZID and HAZOP?
HAZID (Hazard Identification) is the early-stage, open hazard search done at conceptual design or FEED using guidewords over the whole facility, before P&IDs are frozen. HAZOP (Hazard and Operability Study) is the later, node-by-node deviation analysis done on frozen P&IDs during detailed design per IEC 61882. In short: HAZID asks what hazards exist here at all; HAZOP asks how this specific design can deviate from intent. Greenfield projects run HAZID first and HAZOP after the P&IDs are issued.
What is the difference between HAZOP and LOPA?
HAZOP is qualitative and comes first: a node-by-node deviation study on frozen P&IDs that lists hazardous scenarios, causes, consequences, and existing safeguards. LOPA is semi-quantitative and comes after: it takes the high-severity HAZOP scenarios, assigns an initiating event frequency and a probability of failure on demand to each independent protection layer, and compares the residual risk with the tolerable-risk target to set SIL for any new safety instrumented function. HAZOP identifies; LOPA quantifies and sizes the protection. See the HAZOP register template and the LOPA standard reference.
What is the difference between HAZAN and HAZOP?
HAZOP is structured node-by-node deviation analysis using P&IDs that identifies hazards and existing safeguards qualitatively. HAZAN is the consequence and frequency quantification for specific hazard scenarios, often using Quantitative Risk Assessment (QRA) methods. HAZAN typically follows HAZOP to quantify identified hazards.
When is What-If used vs HAZOP?
What-If is an open-ended hazard discussion using engineering judgement and structured 'what if?' questions. Used at early design stages or incident investigation. HAZOP is structured P&ID-driven deviation analysis used at detailed design stage. What-If is broader and less structured; HAZOP is narrower and more rigorous.
What is FMEA in process industries?
FMEA (Failure Mode and Effects Analysis) is the systematic review of failure modes per component or equipment item. Outputs a structured table of failure modes, effects, severity, detection, and risk priority number (RPN). In process industries FMEA is used for critical rotating equipment reliability and safety system design.
Can Pathnovo extract multiple safety study types?
Yes. Pathnovo's HAZOP Safety Intelligence pillar digitises HAZOP, HAZID, LOPA, and What-If studies from PDF reports into structured queryable registers. Each study type maps to specific lifecycle stages and supports OISD audit-readiness.
Related Pages
HAZOP Safety Intelligence
HAZOP, HAZID, LOPA, What-If register digitisation.
HAZID Standard
Early-stage hazard identification study.
LOPA Standard
Layer of Protection Analysis for SIL classification.
SIL Standard
Safety Integrity Level driven by LOPA.
OISD 118 Standard
Indian regulatory framework requiring multi-study safety lifecycle.
HAZOP Register Template
Free IEC 61882 HAZOP register template in Excel.
LOPA Worksheet Template
Free LOPA worksheet in Excel referencing the HAZOP node and deviation.
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