Introduction
Process Safety Management (PSM) is a systematic approach used in industries to prevent major accidents such as fires, explosions, leaks and toxic releases by controlling hazards associated with dangerous chemicals and processes.
It focuses on:
- Designing safe processes
- Maintaining equipment properly
- Training people effectively
- Learning from incidents
- Managing changes carefully
Difference Between Process Safety and Occupational Safety
Process Safety focuses on preventing major accidents such as explosions, fires, toxic releases and large-scale plant failures that can harm people, environment and assets. It deals with equipment, systems, design and process controls.
Occupational Safety focuses on preventing injuries to workers during routine activities — like slips, trips, falls, cuts, electrical shocks, ergonomics and PPE use. It deals with people, behavior and workplace practices.
High-Profile Process Safety Incidents
Bhopal Gas Tragedy (1984, India)
Massive methyl isocyanate (MIC) leak from a pesticide plant due to poor maintenance, disabled safety systems, and lack of emergency preparedness — thousands killed, long-term health and environmental damage.
Texas City Refinery Explosion (2005, USA)
Hydrocarbon vapor cloud ignited during startup of an isomerization unit. Overfilling, faulty alarms, poor safety culture and cost-driven decisions led to 15 deaths and major destruction.
Deepwater Horizon (2010, Gulf of Mexico)
Offshore drilling blowout due to failed well integrity and decision-making under pressure. Blowout preventer failed, leading to explosion, 11 fatalities, and one of the largest oil spills in history.
Common Lesson:
Weak process safety systems → poor design control, ignored warnings, bypassed safeguards, lack of training, and weak leadership — all combine to create catastrophic events.
The Business & Moral Case for PSM
Process Safety Management (PSM) is essential not only to avoid accidents, but to protect people, business and society.
Business case:
PSM prevents costly incidents — explosions, shutdowns, legal penalties, reputation loss and insurance claims — while improving reliability, productivity and investor confidence.
Moral case:
PSM ensures workers go home safely, protects nearby communities, and prevents environmental harm — because human life and public safety are more important than production targets.
Introduction to Risk: Likelihood vs. Severity
Risk in safety means the chance that something bad will happen — and how bad it will be if it happens.
It has two parts:
Likelihood:
How often or how likely an event is to occur.
Severity:
How serious the consequences would be (injury, death, damage, loss, environmental harm).
In simple terms:
Risk = Likelihood × Severity
So even a rare event can be unacceptable if the consequences are extreme — and a frequent event becomes risky even if the harm is small.
Overview of OSHA 1910.119 — U.S. PSM Standard
OSHA 1910.119 is the U.S. Process Safety Management rule that applies to facilities handling highly hazardous chemicals.
OSHA 1910.119 = systematic controls to keep hazardous chemical processes from causing major accidents.
Its goal is to prevent catastrophic releases, fires, and explosions by requiring disciplined control of process risks.
It requires companies to have structured elements such as:
- Process safety information (chemicals, equipment, limits)
- Process hazard analysis (PHA/HAZOP)
- Operating procedures
- Training and competency
- Mechanical integrity of critical equipment
- Management of change (MOC)
- Pre-Startup Safety Review (PSSR)
- Contractors management
- Hot work permits
- Incident investigation
- Emergency planning and response
- Compliance audits
- Trade Secrets
PSM Elements
1. Process Safety Information (PSI): Technology, Equipment, Chemicals
PSI gives correct technical information that helps design, operate, and maintain the plant safely — with no guesswork.
Process Safety Information (PSI) is the complete, verified technical data needed to understand a process and control its hazards before operating it.
It covers three areas:
1. Chemicals
Properties, hazards, reactivity, toxicity, flammability, compatibility (SDS/GHS data).
2. Technology
Process description, flow diagrams, safe operating limits, reaction chemistry, worst-case scenarios.
3. Equipment
Design specs, materials of construction, pressure/temperature ratings, relief systems, electrical classification, drawings (P&IDs).
2. Process Hazard Analysis (PHA) — PSM Element
PHA find hazards early, evaluate risk, add safeguards before something goes wrong.
Reduce the chance of fires, explosions, toxic releases, and catastrophic failures.
Process Hazard Analysis (PHA) is a structured, team-based study used to identify what could go wrong in a process and determine how to prevent or control it.
It systematically reviews:
Process design and operations
Possible deviations and failures
Causes, consequences, and safeguards
Methods include HAZOP, What-If, Checklist, FMEA, etc.
3. Operating Procedures: Development, Content, Safe Limits
Good procedures guide operators, prevent mistakes, and keep the process within safe limits.
Operating procedures are written, step-by-step instructions that explain how to run a process safely and consistently.
Development:
Created by engineers and experienced operators together, based on PSI, PHA findings, and lessons learned.
Content should include:
Startup, normal operation, shutdown, emergencies
Step order and responsibilities
PPE and safety precautions
Alarms, interlocks, and critical checks
consequences of doing it wrong
Safe limits:
Procedures clearly define normal ranges, operating limits, and what to do if limits are exceeded (temperature, pressure, flow, level, etc.).
4. Training: Initial & Refresher — Operators and Maintenance
Training ensures people know what they are doing and why it must be done safely.
Initial training:
Before working independently — covers process basics, hazards, procedures, PPE, emergencies, and roles.
Refresher training:
Done periodically to refresh knowledge, correct gaps, and update changes (MOC, incidents, new procedures).
For operators — focus on:
Process flow and equipment
Normal, startup, shutdown, emergency handling
Alarms, limits, interlocks, consequences of deviation
For Maintenance — focus on:
LOTO- lockout–tagout
PTW- permit-to-work
Isolation
Line breaking
Confined space
Hazards of chemicals and stored energy
5. Contractor Management — Selection, Orientation, Oversight
Contractor management ensures that outside workers perform jobs safely when working in hazardous plants.
Right contractors, properly briefed, closely supervised — reduce accidents and liability.
Selection:
Choose contractors based on safety records, competence, certifications, and past performance — not just cost.
Orientation (before work):
Explain site rules, hazards, PPE, permits, emergency actions, and roles — verify understanding.
Oversight (during work):
Monitor work practices, enforce permits, control access, review incidents, and stop unsafe work.
6. Pre-Startup Safety Review (PSSR): Checklist & Compliance Verification
PSSR is a final safety check done before starting a new or modified process to ensure everything is ready and safe.
PSSR confirms: “Nothing starts until it is proven safe.”
It verifies through a checklist that:
- Construction matches design
- Procedures and PSI are updated
- Operators are trained
- Safety systems and interlocks work
- Permits and inspections are complete
- Hazards identified in PHA are addressed
7. Mechanical Integrity (MI): Inspection, Testing, Preventive Maintenance
Mechanical Integrity (MI) ensures that critical equipment works safely and reliably throughout its life.
It focuses on equipment such as vessels, piping, valves, boilers, relief devices, pumps, compressors, instrumentation, and safety systems.
MI prevents breakdowns, leaks, explosions — by keeping equipment healthy and verified.
Key parts:
Inspection:
find wear, corrosion, leaks, damage.
Testing:
verify safety devices, interlocks, relief systems, alarms.
Preventive maintenance (ITPM):
planned servicing to prevent failure — based on risk, history, and manufacturer guidance.
Also includes:
written procedures, trained technicians, spare parts control, records, and failure investigation.
8. Safe Work Practices (Hot Work, LOTO, Confined Space, etc.)
Safe work practices are standardized rules and permits that control high-risk activities so they don’t create new hazards.
Safe work practices = permits + controls + supervision to keep hazardous jobs from turning into accidents.
They typically cover:
Hot work: welding, cutting — prevent fires/explosions.
Lockout–Tagout (LOTO): isolate energy before maintenance.
Confined space entry: test atmosphere, control entry, rescue plan.
Line breaking & opening equipment: depressurize, drain, purge.
Work at height, excavation, lifting, vehicle movement — as required.
9. Management of Change (MOC): Temporary & Permanent Changes
Management of Change (MOC) is the formal process used to control any change that could affect safety — equipment, process, chemicals, procedures, or people.
MOC prevents “surprise risks” — nothing changes without evaluation.
It ensures that before a change is made:
Hazards are reviewed
Documents and drawings are updated
Training is done
Approvals are given
Temporary changes have clear time limits and controls
Permanent changes: fully engineered, documented, and reviewed.
Temporary changes: allowed only with extra precautions — and must be tracked, reviewed, and reversed or formalized.
10. Incident Investigation — Root Cause Analysis (RCA)
Incident investigation finds out what happened, why it happened, and how to stop it from happening again.
Root Cause Analysis (RCA) looks beyond the obvious to identify failures in systems, procedures, design, training, or leadership — not just human error.
RCA turns incidents into learning — not repeated mistakes.
Common RCA methods include:
- 5 Whys
- Fishbone / Ishikawa
- Fault Tree Analysis
- Timeline / Event & Causal Factor charts
Outcome: corrective and preventive actions that actually remove the root causes.
11. Emergency Planning & Response — Coordination with Local Authorities
Emergency planning prepares a facility to respond quickly and safely to fires, explosions, toxic releases, or other major incidents.
Plan together, practice together — respond faster, save lives, reduce damage.
It includes:
Clear roles, command structure, and communication
Evacuation routes, alarms, muster points
Trained emergency teams and regular drills
Medical support and rescue plans
Coordination with local authorities (fire brigade, police, hospitals, disaster management) ensures outside responders know the site hazards, layouts, chemicals, and contact points — before an emergency happens.
12. Compliance Audits — Effective Audits & Audit Cycles
Compliance audits check whether PSM systems are actually being followed, documented, and improved — not just written on paper.
Audits keep PSM honest — find problems early before incidents do.
They focus on:
Verifying procedures vs real practice
Identifying gaps and weak controls
Reviewing records, interviews, and field conditions
Ensuring past actions are closed properly
Audit cycles:
Audits are done at planned intervals (e.g., every 1–3 years), with follow-ups to track corrective actions until completed.
13. Trade Secrets — Handling Information with Legal Protections (PSM)
Trade secrets are confidential technical or business details (formulas, process design, equipment specs, operating methods) that a company protects for competitive advantage.
Under PSM, companies may protect trade secrets — but cannot hide safety-critical information.
Protect the business — but never at the cost of safety.
Key idea:
Sensitive details stay confidential
Workers, contractors, and regulators must still receive all information needed to work safely
Access is controlled, documented, and shared only on a need-to-know basis — with confidentiality agreements if required
14. Employee Participation — Mechanisms for Involvement
Employee participation ensures workers are actively involved in building and improving process safety — not just following instructions.
People who do the work help design the safety — stronger, practical, and realistic systems.
Key mechanisms include:
Involving employees in PHA, HAZOP, and reviews
Safety committees and regular meetings
Reporting hazards, near misses, and suggestions
Access to PSM information and procedures
Consultation during changes and investigations
PSM Key Technical Concepts & Tools
Hazard Identification Techniques — Bow-Tie Analysis & Checklists (PSM)
Hazard identification helps find what could go wrong before it happens.
Bow-Tie = big-picture risk view; Checklists = practical reminders so hazards aren’t missed.
Bow-Tie Analysis:
Visual method that shows:
The hazard
Causes leading to an incident (left side)
Consequences (right side)
Barriers that prevent and mitigate the event
It helps clearly see where controls are strong — and where gaps exist.
Checklists:
Simple, structured lists of known hazards and best practices, used during inspections, audits, design reviews, and operations.
Layers of Protection Analysis (LOPA) — PSM
LOPA is a semi-quantitative risk assessment method used to check whether existing safeguards are enough to reduce risk to an acceptable level.
LOPA answers: “Are our protections enough — or do we need more?”
It works by:
Identifying a hazardous event
Estimating the frequency (how often it could happen)
Listing independent protection layers (IPLs) such as alarms, interlocks, relief valves, shutdown systems
Calculating how much each layer reduces risk
If risk is still too high, additional safeguards or design changes are required.
Safety Instrumented Systems (SIS) & Safety Integrity Levels (SIL)
Safety Instrumented Systems (SIS) are automatic protection systems that detect dangerous conditions and take action (such as shutting down equipment) to prevent accidents like explosions, fires, or toxic releases.
SIS = safety system that acts automatically.
SIL = how dependable that system must be.
They include sensors, logic controllers, and final control elements (like valves).
Safety Integrity Level (SIL) measures how reliable a SIS must be — how often it is allowed to fail on demand.
SIL ranges from SIL 1 (lowest) to SIL 4 (highest), chosen based on risk and consequences.
Inherently Safer Design (ISD) — PSM Principles
Inherently Safer Design (ISD) means reducing hazards at the source instead of relying only on add-on controls and procedures.
ISD removes or reduces hazards — so less needs to be controlled later.
Core principles:
Minimize: use smaller inventories and lower concentrations.
Substitute: replace hazardous chemicals or processes with safer ones.
Moderate: operate at lower temperatures, pressures, or energies.
Simplify: design processes and equipment so they are easy to operate and hard to misuse.
Quantitative Risk Assessment (QRA) — PSM
QRA = numbers and models that show how big the risk really is.
Quantitative Risk Assessment (QRA) is a data-driven method used to estimate how likely major accidents are and how severe their consequences could be.
It uses models, failure data, and scenarios (fires, explosions, toxic releases) to calculate individual and societal risk, then compares results with acceptable risk criteria.
Purpose:
Support decisions on plant layout, population exposure, emergency planning, and additional safeguards.
Human Factors & Culture
Role of Human Error in Process Incidents (PSM)
Human error is a major contributor to process incidents — not because people are careless, but because systems allow mistakes to occur.
Human error is usually a symptom — fixing the system prevents the mistake.
Key points:
Most incidents involve human factors — usually triggered by system weaknesses.
Design gaps (confusing controls, poor layout) increase error likelihood.
Unclear / incomplete SOPs drive unsafe deviations.
Training and competency gaps lead to wrong decisions under pressure.
Fatigue, workload and time pressure push shortcuts.
Poor communication and shift handover cause misunderstanding.
Weak permit-to-work / override practices bypass safeguards.
Failure to learn from near-misses repeats the same mistakes.
PSM focus:
Design safer systems, strengthen procedures and competency, improve communication, and build a culture that prevents deviations instead of blaming people.
Safety Culture Assessment & Improvement
A strong safety culture means people consistently act — and make decisions — with process safety first.
Assessing it helps uncover attitudes, behaviors, and system gaps that can lead to major incidents.
What assessment looks at:
Leadership commitment — safety value over production.
Employee involvement — everyone speaks up about hazards.
Learning culture — near-misses investigated and shared.
Procedures & compliance — clear, followed, and practical.
Competency — training, qualification, and refresher learning.
Communication & handover — accurate, timely, documented.
Contractor safety — standards equal to employees.
Accountability — fair, no blame — focus on causes.
How to improve:
Visible leadership walks, audits, and open discussion.
Encourage reporting (no punishment for honest mistakes).
Act on findings quickly — close the loop.
Simplify SOPs, remove conflicting priorities.
Regular training, drills, and competency checks.
Learn from incidents company-wide, not just locally.
Managing Operational Discipline (PSM)
Operational discipline means doing the right task, the right way, every time — exactly as designed and documented. It ensures critical safeguards are applied consistently so deviations don’t become incidents.
Core elements:
Follow procedures exactly — no shortcuts, no “work-arounds.”
Clear, practical SOPs — current, accessible, and aligned with reality.
Competent people — trained, qualified, and periodically refreshed.
Pre-job checks & permits — verified, not just signed.
Strong supervision — coaching, field presence, and feedback.
Management of change — never change steps informally.
Accountability with fairness — investigate causes, not blame.
Continuous learning — capture deviations and fix system gaps.
Effective Safety Leadership & Communication (PSM)
Effective safety leadership means leaders set the tone, make safety non-negotiable, and model the behaviors they expect. Clear communication ensures everyone understands hazards, expectations, and their role in preventing incidents.
Key essentials:
Lead by example — visible participation in safety activities.
Safety before production — decisions reflect priorities.
Clear expectations — simple, consistent safety rules.
Two-way communication — encourage questions and concerns.
Regular toolbox talks & briefings — focused, relevant, short.
Timely sharing of incidents/lessons learned.
Recognition for safe behavior — not only for output.
Fair response to errors — learn, don’t blame.
PSM Implementation & Sustainability
Roles and Responsibilities
Line Management: own day-to-day process safety; ensure procedures, training, permits, audits, and resources.
PSM Coordinator: integrate elements, track actions, verify compliance, facilitate reviews, reporting, and learning.
Engineers: design inherently safer systems, maintain integrity, manage changes, support risk assessments.
Developing a PSM Implementation Plan
Gap assessment → priorities → roadmap.
Assign owners, timelines, resources.
Build procedures, training, and verification.
Audit, track actions, and review progress.
Document Management for PSM
Controlled documents, version control, approvals, accessibility.
Traceability for procedures, drawings, permits, MOC, incident reports.
Process Safety Metrics
Leading: training completion, audit findings closed, MOC on time, preventive maintenance, near-miss reporting.
Lagging: incidents, loss of containment, fires/explosions, severity and costs.
Integration with Management Systems
Align PSM with ISO 45001/14001 — risk assessment, competence, change control, emergency planning, audits, continual improvement.
Advanced Topics & Future Trends in PSM
Process Safety in Project Lifecycle
Embed risk reviews from concept → design → construction → commissioning → operation → decommissioning.
Apply inherently safer design, MOC, verification, and handover discipline at every phase.
Cybersecurity for Industrial Control Systems (ICS)
Protect control/SCADA from malware, ransomware, and unauthorized access.
Network segmentation, access control, backups, patching, incident response integration with PSM.
Learning from Near Misses
Treat near misses like incidents: report, investigate, share lessons, close actions.
Focus on weaknesses in barriers, not people.
Impact of Organizational Change
Restructuring, outsourcing, turnover, or budget cuts can weaken safeguards.
Assess risks, clarify roles, retain competence, and manage change formally.
Continuous Improvement in PSM
Regular audits, metrics review, leadership engagement, and lessons learned.
Simplify procedures, remove recurring failures, and sustain accountability.
Capstone & Application (PSM)
Complex Case Study Analysis
Analyze real incidents, identify failed barriers, human factors, and system gaps, then propose practical corrective actions.
Developing a PHA Scenario or an MOC Procedure
Build a simple PHA scenario (hazards, causes, consequences, safeguards, actions) or draft an MOC process with clear steps, approvals, and verification.
Conducting a Table-Top Audit
Review documents, interview personnel, and check compliance against PSM elements — focusing on risks, not paperwork alone.
Final Assessment / Certification
Evaluate knowledge, application, and decision-making to confirm readiness to apply PSM principles in real operations.