Hazard Identification for Oil and Gas MOCs


 In oil and gas, Management of Change (MOC) is the formal control system for modifications to equipment, operating limits, software/logic, chemicals, staffing, or procedures. The most decisive phase is not approval it is hazard identification. If hazards are missed early, downstream engineering and commissioning will “optimise” around incomplete assumptions, and the organisation will unknowingly accept new exposure. Effective hazard identification within MOC connects field reality to structured reviews such as Hazid, Hazop, and risk assessment, producing defensible risk management decisions within a process safety management framework. The goal is straightforward: anticipate credible scenarios introduced by the change, confirm safeguards, and ensure residual risk is tolerable and controlled.

Read: What is Process Safety Management 

1) Define the Change Precisely: Hazard Identification Starts with Scope

Hazard identification quality is proportional to scope clarity. A strong MOC scope statement answers:

  • What is changing (hardware, logic, procedure, organisational interface)?

  • Where are the boundaries (upstream/downstream tie-ins, utilities, flare/vent interface, control system segments)?

  • When does it apply (start-up, shutdown, turnaround, upset recovery, normal operations)?

  • What assumptions are being made (feed variability, corrosion allowance, operator response time)?

In oil and gas facilities, ambiguous scope is the root cause of “hidden” hazards: a valve relocation that changes drainage behavior, a control logic tweak that alters permissives, or a temporary bypass that becomes routine. Treat the scope definition as the first hazard barrier.

2) Choose the Right Hazard Identification Method: Hazid vs Hazop

Not every change requires the same level of study. The hazard identification method should scale with process safety criticality:

  • Hazid is best for early-stage or conceptual changes and for non-standard modifications where the primary need is broad hazard discovery (layout impacts, SIMOPS, occupational hazards with major accident implications, interface risks).

  • Hazop is best when a process design intent exists, and deviations can be systematically tested (flow/no flow, high pressure, reverse flow, high temperature, composition changes, etc.). It is particularly valuable for piping re-routes, new equipment tie-ins, control philosophy changes, and debottlenecking.

A practical rule: use hazid to ensure you are asking the right questions, and hazop to ensure you are not missing deviation-driven failure modes within the defined nodes.

3) Build the Hazard Register Around Change-Driven Scenarios

Hazard identification for MOC should generate scenarios that are “change-specific,” not generic. Organize the hazard register by pathways that MOCs commonly influence:

A) Loss of Containment and Escalation

Consider how the change alters:

  • pressure/temperature envelopes (new operating limits, higher throughput, different phase behavior)

  • materials compatibility (sour service, hydrogen, amines, solvents, inhibitors)

  • corrosion and erosion mechanisms (velocity changes, water dewpoint shifts)

  • flange count, small-bore connections, and leak points introduced

B) Overpressure and Relief/Flare Interactions

Even minor changes can shift relief loads or backpressure. Hazard identification should challenge:

  • blocked-in thermal expansion risks

  • two-phase relieving potential

  • flare header capacity under new operating cases

  • inadvertent isolation of relief paths due to valve rearrangement

C) Instrumentation, Alarms, and Protective Functions

MOCs frequently touch control logic and setpoints. Identify hazards from:

  • altered interlocks or bypasses

  • new nuisance alarms leading to alarm fatigue

  • changes in alarm priorities, trip limits, or permissive logic

  • failure modes introduced by software updates or cybersecurity controls

D) Human Factors and Procedural Drift

Many incidents originate from operational ambiguity after change. Identify hazards related to:

  • new line-up requirements or valve sequencing complexity

  • changes to abnormal situation handling (startup with different warm-up rates, new recycle behavior)

  • maintenance tasks with new energy sources or isolation points

  • organizational changes affecting handovers, staffing, or contractor interfaces

E) SIMOPS and Temporary Operating Modes

Construction tie-ins, hot work, and temporary bypasses create time-bound hazards. A robust hazid explicitly captures temporary states, defines controls, and sets “removal conditions” so temporary risk does not become permanent exposure.

4) Convert Hazards into Structured Risk Assessment

Hazard identification outputs must flow into risk assessment with disciplined assumptions. Key expectations:

  • Define initiating event frequency bands appropriate to the site’s risk matrix.

  • Estimate consequence severity using realistic escalation assumptions (congestion, occupancy, ignition probability).

  • Credit safeguards only if they are independent, reliable, and verifiable.

This is where risk management quality is determined: not by how many safeguards are listed, but by whether they genuinely reduce risk and can be maintained. If a safeguard depends on perfect operator timing, treat it cautiously unless training, cues, and drills support it.

5) Safeguard Selection and the Risk Management Argument

Once risk is characterized, hazard identification supports decision-making on safeguards. Good practice is to classify safeguards as:

  • Inherently safer (reduce inventory, lower pressure, eliminate ignition sources)

  • Engineered controls (SIS, relief devices, isolation, detection)

  • Administrative controls (procedures, permits, inspections, operating limits)

A refinery or upstream facility with mature process safety management will require a documented rationale for accepting residual risk especially if recommendations are rejected. Record why, and what alternative control (if any) provides equivalent protection.

6) Outputs that Make Hazard Identification Actionable

To avoid “study theatre,” hazard identification for MOC should produce practical deliverables:

  • scenario-based action list with owners and due dates

  • barrier verification requirements (what must be tested/inspected before start-up)

  • updated operating envelope (limits and required responses)

  • documentation update list (P&IDs, cause-and-effect, procedures)

  • training impacts and competency needs

These outputs set up successful MOC closure later without relying on memory or informal agreement.

Conclusion

Hazard identification is the technical backbone of oil and gas MOCs. By using Hazid for broad discovery, hazop for systematic deviation testing, and disciplined risk assessment to select defensible safeguards, organisations implement risk management that is real, verifiable, and sustainable. Done well, this approach strengthens process safety management by ensuring each change improves performance without silently increasing major accident potential.

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Read More On MOC Reviews / Close-Outs 

https://synergenog.com/core-services/operational-safety/moc-reviews-close-outs/

SynergenOG - Process safety management consultants

https://synergenog.com/process-safety-management-consultants/

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