1.3 Hazards and Effects Management Process (HEMP) & Risk Matrix

1.3 Hazards and Effects Management Process (HEMP) & Risk Matrix

Framework Overview: The Hazards and Effects Management Process (HEMP) provides a structured, systematic approach to managing Health, Safety, and Environment (HSE) risks throughout the entire lifecycle of an industrial asset or operation. Used extensively across the Nigerian oil and gas sector (including NNPC, Shell SPDC, Chevron Nigeria, and TotalEnergies) and heavy manufacturing industries, HEMP ensures that hazards are systematically identified, assessed, controlled, and mitigated.

In major hazard facilities—such as offshore drilling rigs, crude oil tank farms, refineries, and chemical processing plants—managing safety requires formal quantitative and qualitative frameworks to evaluate complex operational risks. HEMP serves as the central pillar of the HSE Management System (HSE-MS), ensuring that operational risks are reduced to As Low As Reasonably Practicable (ALARP).

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The Continuous 4-Step HEMP Cycle

HEMP operates as a continuous, closed-loop risk management process consisting of four sequential stages:

[1. IDENTIFY] ➔ [2. ASSESS] ➔ [3. CONTROL] ➔ [4. RECOVER]

Stage 1: Identify (Hazards & Potential Effects)

In this initial phase, multidisciplinary teams systematically spot all inherent hazards associated with a facility design, process modification, or routine/non-routine operation.

• Hazard Identification (HAZID): High-level review conducted early in project design to identify macro hazards (e.g., high-pressure gas reservoirs, toxic $H_2S$ fields).
• Hazard and Operability Study (HAZOP): Detailed engineering analysis using process guide words (No Flow, More Pressure, Reverse Flow) to evaluate process deviations in piping and instrumentation diagrams (P&IDs).
• What-If Analysis & Site Walkthroughs: Operational reviews conducted prior to maintenance or turnaround work to spot localized physical hazards.

Stage 2: Assess (Risk Levels & Criticality)

Once hazards are identified, the team evaluates the likelihood of an unwanted release or incident occurring and the potential severity of its consequences across four standardized impact categories:

1. People: Fatalities, permanent disabilities, Lost Time Injuries (LTI), or Medical Treatment Cases (MTC).
2. Assets: Direct physical destruction of machinery, piping, platforms, and associated production loss financial costs.
3. Environment: Uncontrolled crude oil spills into waterways, toxic chemical venting, groundwater contamination, and NESREA/NOSDRA regulatory fines.
4. Reputation: Local community blockades, national press coverage, regulatory license suspension, and international brand damage.

Stage 3: Control (Preventive Barriers)

Control measures are engineered and administrative safeguards implemented upstream of a hazardous event to prevent loss of containment or safety breaches. Examples include:

• Automated Emergency Shutdown (ESD) valves and overpressure interlocks.
• Double-block-and-bleed valve arrangements and Lockout/Tagout (LOTO) energy isolation.
• Preventive maintenance schedules, pressure vessel wall-thickness testing, and certified operating procedures.

Stage 4: Recover (Mitigation & Emergency Measures)

Recovery measures are safeguards activated downstream of an event (after a loss of containment has occurred) to minimize consequence severity:

• Fixed deluge fire suppression systems and gas detection alarm networks.
• Spill containment bund walls, oil skimmers, and chemical dispersant boom deployments.
• Site emergency evacuation plans, muster station accountability, and trained industrial first aid teams.

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The Bowtie Risk Model & Barrier Decay

The Bowtie methodology visually connects threats, barriers, the central hazardous event ("Top Event"), and ultimate consequences.

Key Components of the Bowtie Diagram

• Threats: The initiating causes (e.g., internal pipe corrosion, operator error, overpressurization).
• Preventive Barriers: Controls placed on the left side of the Top Event to stop threats from triggering the event.
• Top Event: The point where control over the hazard is lost (e.g., Loss of Primary Containment of Hydrocarbon Gas).
• Escalation Factors: Conditions that degrade or defeat a barrier (e.g., salt-spray corrosion causing ESD valve sticking, or power failure disabling alarms).
• Escalation Factor Controls: Secondary safeguards designed to maintain barrier integrity (e.g., backup battery UPS systems, routine valve function testing).
• Mitigation Barriers: Controls placed on the right side of the Top Event to reduce consequence severity after the event occurs.

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The 5x5 Qualitative Risk Assessment Matrix (RAM)

The Risk Assessment Matrix (RAM) standardizes qualitative risk evaluation by plotting Likelihood against Consequence Severity, yielding a numerical Risk Rating ($1 \text{ to } 25$).

$\text{Risk Rating} = \text{Likelihood Rating} \times \text{Severity Rating}$

Standard Likelihood Scale (1 to 5)

1. Remote (Improbable): Has never occurred in the global oil & gas or process industry ($<10^{-5}/\text{year}$).
2. Unlikely: Has occurred in the international industry, but never within company operations.
3. Possible: Has occurred at least once in company operations over the past decade.
4. Likely: Occurs several times per year within regional company operations.
5. Almost Certain (Frequent): Occurs repeatedly at the specific site or facility during routine operations.

Standard Consequence Severity Scale (1 to 5)

1. Slight: First Aid Case (FAC); negligible asset damage ($<\text{₦500,000}$); minor localized chemical drip within secondary containment.
2. Moderate: Medical Treatment Case (MTC) or Restricted Work Case (RWC); minor asset damage ($<\text{₦5,000,000}$); localized spill contained on site.
3. Major: Lost Time Injury (LTI) or partial disability; moderate facility damage ($<\text{₦50,000,000}$); minor off-site environmental impact.
4. Severe: Single fatality or permanent total disability; major structural/equipment destruction; significant off-site spill requiring external remediation.
5. Catastrophic: Multiple fatalities; total facility loss or platform destruction ($>\text{₦1,000,000,000}$); severe regional environmental disaster (e.g., major offshore blowout).

Risk Matrix & Tolerability Boundaries

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Management Authorization Hierarchy by Risk Level

Risk ratings dictate mandatory operational controls and management approval levels before work permits (PTW) can be issued:

• Low Risk (Green, Score 1–4): Risk is broadly acceptable. Managed via standard operating procedures (SOPs) and routine toolbox talks. Approved by the Work Site Supervisor.
• Medium Risk (Yellow, Score 5–12): Risk is tolerable under ALARP conditions. Requires task-specific Job Safety Analysis (JSA), documented barrier checks, and formal sign-off by the HSE Manager / Area Operations Superintendent.
• High Risk (Red, Score 15–25): Risk is unacceptable. Operations are strictly prohibited. Work cannot commence until permanent engineering controls or process redesign lower the residual risk score into the Yellow or Green zones. Authorization requires Executive Management / Managing Director approval.

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Inherent Risk vs. Residual Risk: Worked Industrial Scenario

Understanding the shift from inherent to residual risk is critical for permit issuance:

• Inherent (Uncontrolled) Risk: The raw risk level of an unmitigated hazard.
• Residual Risk: The net risk remaining after engineered safeguards, administrative controls, and personal protective equipment are fully applied.

Practical Worked Scenario: Hydrocarbon Pipe Breaking & Valve Replacement

A crew in a Niger Delta flow station must replace a corroded gate valve on a live 8-inch crude oil manifold operating at $40\text{ bar}$ pressure.

1. Initial (Inherent) Risk Evaluation:

   • Hazard: Pressurized flammable crude oil containing $200\text{ ppm } H_2S$.
   • Potential Event: Flange parting releasing high-pressure crude spray and toxic gas cloud.
   • Inherent Likelihood: 4 (Likely - high pressure and vibration).
   • Inherent Severity: 4 (Severe - potential worker fatality and major oil spill into creek).
   • Inherent Risk Score: $4 \times 4 = 16$ (High / Red Risk - Work Prohibited).

2. Implementation of Risk Controls (HEMP Barriers):

   • Engineering Control: Depressurize, drain, and flush manifold with nitrogen; install double-block-and-bleed blinds with LOTO padlocks.
   • Administrative Control: Conduct gas test ($0\text{ ppm } H_2S, 0%\text{ LEL}$); issue Hot Work PTW; establish $25\text{m}$ exclusion zone.
   • PPE Barrier: Work crew equips with positive-pressure SCBA (Self-Contained Breathing Apparatus) and flame-resistant coveralls.
   • Recovery Measure: Deploy fire watch with dual 9kg Dry Chemical Powder extinguishers and pre-position oil spill containment booms downstream in the creek.

3. Residual Risk Evaluation:

   • Residual Likelihood: 1 (Remote - manifold depressurized, isolated, and verified zero gas).
   • Residual Severity: 3 (Major - residual line drip causing minor localized spill).
   • Residual Risk Score: $1 \times 3 = 3$ (Low / Green Risk).
   • Conclusion: Work permit approved by Operations Superintendent; task proceeds safely.