30 May 2006

Leak Of Rupture Disc

Safety Incident Topic: Rupture Disc Leak
Location Of Incident: Whitting USA
Date Of Incident: 30th March 2006

Brief Account Of Incident
At the FCU 500 / 600 Fractionator Towers, the relief valves are protected from the process hydrocarbons by rupture disks.

On Thursday, March 30, 2006, it was discovered that the rupture disks were leaking, with system pressure equalized on both the top and bottom of the rupture disk. Rupture disks may not function as designed if pressure is allowed to build between the disk and the relief valve. This disk back pressure potentially compromises relief system capacity.

Potential Outcome
Potential that the rupture disks and thus relief valve would fail to operate properly in a release scenario, compromising relief system capacity.

Action Taken
- We are removing the rupture disks from the Fractionator RVs at both FCUs. We will work continuously until it is completed.
- We have formed a joint union / management investigation team to understand and determine what processes and management systems were or were not in place that led us to our current situation.
Additional teams will:
- Complete an (Root Cause Failure Analysis) RCFA for the rupture disks at the FCUs.
- Evaluate operation and safety for FCU Fractionator Tower RVs without the use of rupture disks.
- Review all other installations at Whiting where rupture disks are in service with RVs.
- Accelerates a previously scheduled project to upgrade the existing RV metallurgy. This will eliminate the need for rupture disks long term.

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