TL;DR

Flare tip burnback means combustion is inside the tip body. Verify purge gas flow and steam injection immediately. Activate the site emergency response plan.

What you might see

bright flame visible inside the flare stack
flare tip temperature sensor reading extreme high
steam or purge gas flow reduced below minimum
combustion noise heard inside the stack

Likely causes

Tap to mark as ruled out

Purge gas flow below the minimum velocity required to prevent air ingress and burnback
Steam injection rate reduced or lost allowing oxygen ingress during low flare flow
Tip erosion or damage creating a cavity where flame can anchor inside the tip
Wind conditions creating a downdraft that pushes combustion back inside the tip

Required tools

Purge gas flow meter
Steam flow meter (if steam injection is fitted)
Thermal camera (for tip temperature monitoring from a safe distance)

Safety first

Flare tip burnback is a fire event on active equipment processing hydrocarbon gas. Activate the site emergency response plan and do not approach the flare stack.
Purge gas is a flammable or inert gas depending on the system design. Confirm purge gas type and ventilation requirements before adjusting purge gas valves.
Flare stack work requires hot work permit, fall protection, and coordination with the site fire team. No individual should approach a flare with an active burnback condition.

Procedure

6 steps · ~30 min

1
Immediately verify the purge gas flow rate at the purge gas meter or indicator. Increase purge gas to the minimum safe velocity.[1]
2
Verify the steam injection rate (if fitted) and increase as necessary to purge air from inside the tip.[1]
3
Check the flare gas flow rate. Very low flow during plant turndown increases the risk of burnback.
Warning: Burnback is a high-priority safety event. Notify the site fire team and follow the flare emergency procedure in the site ERP. Do not approach the flare stack.
4
If burnback is confirmed, follow the site emergency procedure which typically involves increasing purge gas and flare gas flow to extinguish internal combustion.
5
After the event, plan a flare tip inspection at the next planned shutdown. Burnback typically causes tip damage that requires inspection and potentially tip replacement.
6
Review the purge gas minimum flow setpoint. Confirm it is set at or above the manufacturer's minimum flame velocity recommendation.

Sources

John Zink Hamworthy (Koch) John Zink ZTOF / EEF Flare System general technical documentation, John Zink Hamworthy (Koch)
John Zink ZTOF / EEF flare system general burnback prevention and emergency response procedures (general)

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