BOEMRE Reissues Alert 259 On Offshore Mooring After Chain-Link Failure

 Accident report, mooring, mooring, Offshore, Safety Alerts  Comments Off on BOEMRE Reissues Alert 259 On Offshore Mooring After Chain-Link Failure
May 302011
 

Investigation determined that a 6 3⁄4-inch diameter, 862-pound chain link in the tether chain had fractured and separated near its butt weld.

In early 2011, a single point mooring system for a deepwater Gulf of Mexico (GOM) project failed at the tether chain for a free-standing hybrid riser, allowing the buoyancy air can and the free-standing flowline riser to separate. The 440-ton buoyancy air can rose suddenly to the surface while the free standing riser collapsed. Based on the investigation of this event and a review of historical events, BOEMRE is revising and re-issuing Safety Alert #259.

 

The investigation determined that a 6 3/4-inch diameter, 862-pound chain link in the tether chain had fractured and separated near its butt weld. Analysis of the fracture indicated that the chain link had a weld repair and the fracture initiated in the middle of the weld. Three links of the 24-link tether chain were found to have weld repairs. After the chain had been heat treated, the non-US based manufacturer had made weld repairs to the chain by grinding defects and filling the void with weld material. The chain was being built in accordance with Det Norske Veritas (DNV) Offshore Mooring Chain standard. Post heat treat weld repairs are disallowed per DNV’s Offshore Mooring Chain standard. The post heat treat weld repairs made the chain susceptible to hydrogen induced stress cracking due to the extreme hardness of the weld material and the residual stress within the weld. Continue reading »

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Vermilion 380 A Platform Fire: Corroded Tube Led To Fire

 Accident, Accident report, fire, offshore  Comments Off on Vermilion 380 A Platform Fire: Corroded Tube Led To Fire
May 292011
 

Ageing, poorly maintained equipment failed, resulting in a fire and loss of power that left crew without the means to fight it.

When a 30-year-old corroded fire tube collapsed on Mariner Energy’s Vermilion 380 A Platform and started a fire, electrical power was lost to firepumps leaving the 13-member crew without a firewater system. Ultimately, the crew was forced to evacuate the platform, and all were later transported to safety.

The Bureau of Ocean Energy Management, Regulation and Enforcement (BOEMRE)has released the findings of its investigation into a fire that occurred Sept. 2, 2010, on Mariner Energy Inc.’s, Vermilion 380 A oil and natural gas production platform located approximately 102 miles off the coast of Louisiana. Continue reading »

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