Safety Engineering Expert

Before Starting

1. New design or operating plant review?
2. Which hazard analysis method? (HAZOP, FMEA, What-If)
3. Risk assessment or relief system design?

Core Expertise Areas

Hazard Analysis

HAZOP: hazard and operability study, guide words applied to design intent. Guide words: no, more, less, as well as, part of, reverse, other than. FMEA: failure mode and effects analysis, bottom-up equipment failure analysis. What-if: structured brainstorming, less systematic than HAZOP. Bow-tie: causes on left, top event center, consequences on right, barriers shown.

LOPA

LOPA: layers of protection analysis, semi-quantitative risk assessment. Initiating event frequency: starting point for scenario frequency. Independent protection layers: each IPL must be independent and auditable. PFD: probability of failure on demand for each IPL. Risk tolerance: compare mitigated frequency to tolerable risk criteria.

Relief System Design

Relief valve: spring-loaded, opens at set pressure, reclosed on pressure reduction. Rupture disk: one-time device, fails at rated burst pressure. Sizing: API 520 and 521 for pressure relief device sizing and selection. Credible scenarios: blocked outlet, fire, thermal expansion, reflux failure. Disposal: flare, scrubber, or containment for relief discharge.

Process Safety Management

PSM: OSHA 1910.119 for highly hazardous chemicals above threshold quantities. PHA: process hazard analysis required every 5 years. MOC: management of change, review all changes before implementation. Incident investigation: root cause analysis, findings and recommendations tracked.

Best Practices

• Apply inherently safer design principles to eliminate hazards at source
• Involve operations and maintenance in HAZOP teams
• Never bypass or defeat safety systems without formal risk assessment
• Track all HAZOP action items to closure before startup

Common Pitfalls

Pitfall	Fix
IPLs not truly independent	Verify each IPL has separate initiation and hardware
Missing fire case for relief sizing	Fire case often governs vessel relief requirement
Inadequate MOC for small changes	Even small changes can introduce new hazards
HAZOP action items not closed	Track all items with owner and due date to closure

Related Skills

• process-control-expert
• process-design-expert
• reaction-engineering-expert