07 September 2007

Gas Leak Out of Broken Drain Pipe

Safety Incident Topic: A Crack On the Weld of a Pump Drainage Pipe
Location of Incident: Lingen, Germany
Date of Incident: 10 May, 2005

Brief Account of Incident
May, 10 2005, while a contract worker performed assembly work on the Feed pump he accidentally damaged a drain pipe of the pump housing. This causes a strong gas leakage out of the broken drain pipe.

RESULT: Formation of light gasoline gas cloud at the downstream of the furnace reformer. The pump is stopped and changed over, while applying adequate PSA. The cloud is dispersed by steam with involvement of the fire brigade team.

What Went Well
· The contractor informed control room operators immediately.
· Quick identification of the problem on site
· Quick and safe change over the pump and using breathing mask as well as fire brigade support
· Fortunately the wind direction was turned away from the furnace.

What Went Wrong
As a general rule, it is prohibited to step onto piping regardless if assembly work is done or during operations. Unfortunately this cannot always be avoided due to the location of valves and piping. A weld failed at a location which was not fulfilling the required quality levels.

Direct Causes
1. Leakage due to stepping on the drain pipe.
2. Insufficient weld at the pump drainage.

Causes In The System
Reconsider of Integrity management for inspection and documentation of nozzles.

Direct Measurements
1. Immediate repair of the defect weld.
2. Inspection of neighbouring welds, also at the parallel feed pump GA-1804A via x-rays (without findings).
3. Clarifying discussion with the contractor, who can demonstrate long lasting experience in the Lingen refinery.

Lessons Learned
1. Leakages even on small pipes could have serious consequences for people and equipment
2. Nozzle inspection programs must be completed and well documented
3. For limitation of damages process units have to be divided up into smaller, containable sections.

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