Process Safety · Lesson 50 · 8 min read

An Unlit Flare Can Turn Emergency Disposal Into a Major Release

A flare is intended to convert a hazardous gas release into controlled combustion at a safe location. That protection depends on more than an open route to the flare tip. The pilot must remain available, flame failure must be detected, re-ignition must be dependable, air must be kept out of the header, and operators must know what to do when any part of the function is impaired.

Why an unlit flare is a major-hazard condition

During a process upset, relief or depressurisation flow can contain a large quantity of flammable, toxic or corrosive vapour. A functioning flare brings that material to a stable flame and destroys much of the hazardous content. If the flame is absent, the same flow may leave the tip as unburned gas. Wind and weather then control where the cloud travels and whether it reaches people, air intakes, structures or an ignition source.

If air enters a flare header during low-flow conditions or shutdown, a flammable mixture can form inside the system. Attempted lighting without the required purge can create flashback. A flare flameout is therefore not simply an environmental deviation; it can remove a major-accident barrier while creating a second ignition hazard.

UK HSE guidance identifies reliable pilot and ignition systems and flashback protection as major flare-safety issues. Its offshore loss-of-containment inspection guidance also calls for arrangements that prevent air ingress, clear drains, adequate purge, controlled re-ignition after shutdown and consideration of gas dispersion before unignited venting.

Official evidence: ignition and purge cannot be assumed

In a March 2022 enforcement notice, HSE recorded that a syngas flare had no fixed ignition device. The notice stated that unignited syngas could create an explosive atmosphere and also identified the absence of defined nitrogen-purge arrangements before startup. This was an enforcement finding, not an FPSO incident, but it illustrates why an open discharge path is not enough.

IOGP's supplementary flare-package specification requires functional testing of ignition and flame-detection systems. Where a risk assessment requires two independent ignition systems, it specifies automatic re-ignition on detection of pilot-flame failure, and it addresses maintaining at least one ignition system while a continuously operating flare remains in service. The exact architecture must follow the installation's approved design basis; this lesson supplies no universal redundancy rule.

Hypothetical FPSO example: pilot flame is not confirmed

Hypothetical example—not a documented incident: An FPSO is preparing for a controlled process depressurisation after a shutdown. The control room receives an uncertain pilot-flame indication, and the normal fuel-gas supply has been disturbed by the same shutdown. The team does not assume that heat seen on another instrument proves a stable pilot, and it does not proceed simply because the flare header is available.

Operations pause the planned release, verify the approved pilot-status indications and ignition-system availability, check the purge arrangement and current wind conditions, and escalate the barrier impairment. They use the installation's authorised recovery procedure and confirm the required purge before any re-ignition attempt. If emergency flow cannot be avoided, the emergency response follows the safety case and approved procedures. This example creates no permission to delay an emergency action or improvise flare lighting.

Critical controls

Reliable pilot fuel and ignition: the system should remain suitable across normal operation, startup, shutdown and utility disturbances. Shared utilities and common equipment should be considered because one failure can remove both the flare demand response and the ignition source.

Dependable flame detection: pilot status needs credible indication. The detector, signal path, alarm, logic and operator response should be tested as a function, including failure and restoration states. A normal icon alone is not proof of combustion.

Purge and flashback prevention: the approved design should keep air from moving back into the header. Purge availability, header drains, seals and low-flow conditions require monitoring. Following a flameout or shutdown, re-ignition should not occur until the required purge condition has been achieved.

Impairment and operating limits: a failed pilot, unreliable detection or unavailable ignition system should trigger the installation's defined impairment process. The response may restrict process changes, planned depressurisation or other activities that could add flare load.

Dispersion awareness: if unignited gas could be released, the team must consider composition, rate, duration, wind and the location of people, air intakes and ignition sources. A high discharge point does not make an unburned cloud harmless.

Operational and leadership actions

Operators should challenge disagreement between flame detectors, temperature indications, visible observation and fuel-gas status. They should know the approved escalation path, the conditions for attempted re-ignition and the actions that are prohibited when purge or ignition is uncertain.

Leaders should ensure that flare ignition is treated as a safety-critical function, not only an emissions system. Performance standards should cover pilot availability, detection, ignition, purge, utilities, proof testing, maintenance and restoration. Repeated flameouts, unreliable indications or temporary ignition arrangements deserve prompt engineering review and clear operating restrictions.

Three practical actions

• Trace the whole function: follow one credible depressurisation demand from the process source through the header, purge, pilot fuel, ignition, flame detection and final operator response.
• Review impairment evidence: check every current pilot, detector, ignition or purge defect, its approved restriction, owner and restoration test.
• Rehearse flameout response: confirm that the team can pause avoidable flare loading, assess dispersion and follow the authorised purge and re-ignition procedure without improvisation.

Video availability

No directly relevant official incident or technical video was identified during source verification on 1 November 2026. Unrelated media has not been embedded; the primary written guidance and enforcement record below are provided instead.

Takeaway and team discussion

Key takeaway: a flare route is protective only when ignition, combustion and flashback prevention are available and verified.

Discussion question: if our flare pilot indication became uncertain during a shutdown today, what evidence would prove the ignition and purge barriers were available before the next avoidable flare load?

Continue in the Process Safety hub, and connect this lesson with utility-independent shutdown protection, relief-system destination, end-to-end detection functions and complete disposal-path assurance.

Verified primary references

1. UK HSE: Inspection of Loss of Containment—official offshore inspection guidance covering flare purge, drains, ignition, re-ignition and unignited-gas dispersion.
2. UK HSE: Relief systems and vent systems—official technical guidance identifying reliable pilot ignition and flashback protection as major flare-safety issues.
3. IOGP JIP33 S-722: Supplementary Specification for Flare Package—primary industry specification addressing ignition-system maintainability, flame-failure detection, re-ignition and functional testing.
4. UK HSE enforcement notice 312494343—official record describing hazards from a flare without fixed ignition and from undefined purge arrangements.
5. IOGP: Flaring guidance and publications—official industry overview linking flare design, operation, ignition and venting controls.

Published and sources checked 1 November 2026. Educational discussion only: apply the installation's approved safety case, process design basis, performance standards, flare philosophy, impairment controls and operating procedures. No universal purge rate, purge duration, pilot arrangement or permission to vent unignited gas is supplied.

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