Risk + Safety + AMC

Layer of Protection Analysis (LOPA)

Semi-quantitative risk evaluation of safeguard adequacy.

HAZOP identifies the deviation. LOPA quantifies whether the existing safeguards reduce the risk to tolerable. Where they don't · the gap is the Safety Integrity Level (SIL) required for the Safety Instrumented System. IEC 61511 compliant. The foundation for SIS design.

Why this matters

Why LOPA bridges HAZOP findings into SIS specification

A HAZOP finding · 'high temperature in reactor R-101 leads to runaway exotherm' · doesn't automatically tell you whether the existing high-temperature trip is adequate. LOPA closes the gap. It assigns initiating event frequency, credits each independent protection layer (BPCS, alarms with operator response, mechanical relief, SIS), and arrives at a residual frequency that is either tolerable or not. If not, the residual frequency gap is the SIL required for the SIS. This semi-quantitative bridge between qualitative HAZOP and engineered SIS is what IEC 61511 mandates · we deliver it to the standard.

Method

How we deliver LOPA Analysis

CEng MIE India-signed deliverables · LiDAR-powered where applicable · digital twin handover ready · routes to the Risk + Safety + AMC practice lead within 24 hours.

Scenario extraction

High-severity HAZOP findings extracted as LOPA scenarios. Initiating event + consequence + existing safeguards documented.

Initiating event frequency

Industry-typical frequencies (CCPS, OREDA, your own incident history) assigned. Validated against operating experience.

Independent protection layer credit

Each IPL credited per IEC 61511 rules · BPCS (1 only), alarms with operator response (1 if procedure documented + tested), mechanical relief, SIS layers.

Residual frequency vs tolerable

Residual frequency computed. Compared to your corporate / regulatory tolerable risk criteria. Gap quantifies SIL requirement.

SIL allocation + report

SIL 0 / 1 / 2 / 3 allocated per scenario. CEng MIE-signed. Feeds directly into SIS specification.

Standards + compliance

Built to the standards your auditors quote

Reports reference the international and national standards your regulators, F500 audit teams, and corporate process safety leads cite. Every deliverable signed by a Chartered Engineer (CEng MIE India).

IEC 61511 · Functional safety · Safety instrumented systems for the process industry
IEC 61508 · Functional Safety of Electrical/Electronic/Programmable Electronic Safety-related Systems
CCPS Guidelines for Initiating Events and IPLs
API RP 14C · Analysis, Design, Installation, and Testing of Basic Surface Safety Systems
OSHA PSM (USA), CER (India), HSE 1989 + COMAH (UK)

Anonymous case anchors

What this looks like in production

Three landmark engagements from our verified roster · quantified outcomes, no client names disclosed without written permission.

Refinery, India · hydrocracker LOPA

127 LOPA scenarios. 14 required SIS (mostly SIL 2). SIS gap closed in next turnaround.

Petrochem, KSA · ethylene plant

Combined HAZOP + LOPA workshop. SIL allocations validated against Aramco SAES guidance. Pre-empted operator-mandated reviews.

Pharma, USA · reactor block LOPA

Pharma reactor block LOPA · 42 scenarios. SIS sized for 8. Linked to GMP process safety chain.

Frequently asked

LOPA Analysis · the practical questions

Do you do LOPA standalone, or must it follow HAZOP?

LOPA almost always follows HAZOP · the scenarios come from HAZOP findings. We've done standalone LOPA for clients who have current HAZOP results but no LOPA, but the cleaner pattern is combined HAZOP + LOPA in one engagement.

What tolerable risk criteria do you use?

Your corporate criteria first. If none documented · we recommend criteria per CCPS or industry-typical (e.g. 10^-5/yr for fatality, 10^-3/yr for major property damage). Documented in the report as a precondition.

Can you also do quantitative QRA?

Yes · we offer both LOPA (semi-quantitative) and QRA (fully quantitative). Most clients use LOPA for SIL allocation and QRA for plot-plan / siting / consequence analysis. Both delivered by the same practice.

How do you handle conditional modifiers?

Conditional modifiers (probability of ignition, probability of fatality given event, time at risk) are applied per CCPS guidance, transparent in the LOPA spreadsheet so the client can audit the assumption chain.

Will this output drive our SIS engineering directly?

Yes · the LOPA output (SIL allocation per safety function) is the input to SIS specification. We can either hand over to your I&C engineering or continue into SIS architecture design as a separate scope.

Scope your LOPA Analysis engagement.

Tell us your plant, region, and scope · a named Chartered Engineer responds within 24 hours.

4 fields. No phone interview to start.
Per-discipline routing to the Risk + Safety + AMC practice lead.
Anonymous case anchors sent with first reply.
Same-day callback for deadline-driven enquiries.

Risk + Safety + AMC Scoping

HAZOP/LOPA/SIL/QRA · 5-year AMC retainer · Practice Lead Safety responds in 24 hr.