IOGP high potential event report

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Incident ID: 2516
Production operations

Incident description:

Whilst attempting to start exporting hydrocarbons, there was a leak from a failing valve stem packing on the main oil line export pump recycle flow loop. There was a loss of primary containment with high potential, resulting in a platform muster, ESD and EPD. Approx 82 kg of hydrocarbons were released, resulting in an oil sheen.

What Went Wrong:

- Due to high velocities flow, erosive particles (suspected to be sand), high pressure drop and constant use, the flow control valve was washed out, causing unconstrained flow through the recycle line. - Normally two pumps were in service. One pump had been offline for a few months due to maintenance. During the start-up both pumps were online to re-instate the pump that had been offline. The high velocity through the combined recycle line was transferred to the flow control valve on the second pump, causing already loose gland nuts to unscrew. These nuts provided the force to energise the packing, creating a leak path for the fluids to atmosphere. It was believed the nuts were loose when the valve arrived on the platform and the valve was installed as received. - Issues with flow transmitters (over the past 18 months) had led operators to believe that flow readings were spurious.

Corrective Actions:

- Review level of surveillance (inspection and monitoring). - Review quality assurance (QA) checks and define QA expectations from vendors. Consider QA checklist for offshore crew. - Review work instruction for gland packing tightening during valve commission and installation. - Review instruments are not out of range for current operating condition.