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TEG Fire at gas dehydration unit
Country: SPAIN - Europe
Location: ONSHORE : Other fixed installation
Incident Date: 15 May 2013 Time: ---
Type of Activity: Maintenance, inspection, testing
Type of Injury: Explosions or burns
After a TEG (Triethylene glycol) low low level alarm at the natural gas dehydration unit, the unit was stopped and the operator waited 2 hours before opening the TEG inlet. A fire occurred when the TEG vapors, coming from inside the accumulator tank, reached
the exhaust stack during the TEG refilling operation. The burner zone has restrictions for operator escape, although on this occasion the operator reached the TEG inlet cap from outside the zone and was not caught by the fire. The fire detector produced a
level 1 emergency shut down and the fire was put out by the internal fire brigade without significant consequences.
What Went Wrong?:
- Opening the cap of TEG accumulator tank with vapors inside due to insufficient time for cooling the reboiler unit.
- Error in implementation of permit to work due to refilling operation being considered as routine.
- The design of the unit directs the vapors coming out of the refilling inlet towards a hot spot.
- Combustion soot had accumulated inside the exhaust gas stack, up to 3/4 of the internal section, contributing to a longer time for cooling of the hot spots.
- TEG inlet aiming to a hot spot is considered to be an error in design, causing that TEG vapor is directed to a hot spot when the inlet cap is opened.
- No written instructions were available, specifying how to perform the task (required isolations, time for cooling, unit operating condition, etc.)
- Deficient inspection and maintenance plan: the periodic inspection of exhaust pipe for burners was not included in plan.
Front and side view of the dehydration unit. TEG inlet design aiming to hot spot.
Dehydration unit involved in the incident. Detail of TEG inlet.
Corrective Actions and Recommendations:
- The TEG inlet shall be checked/modified to ensure that vapors are evacuated to a safe place.
- A technical instruction shall be prepared to describe TEG refilling operation.
- Include the inspection of exhaust pipe for all the units with burner in the inspection and maintenance plan.
Safety Alert number: 249
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