VALARIS DS-16 seen alongside on the shipyard [U.S. Coast Guard photo]
A deteriorated bollard led to a 752 foot lengthy drillship breaking away and colliding with a cargo vessel in Pascagoula, Miss., final yr, in line with the National Transportation Safety Board (NTSB). The breakaway resulted in almost $5 million in damages.
On March 12, 2022, the cellular offshore drilling unit VALARIS DS-16, a 2015-built GustoMSC P10,000 drillship, was on the ST Engineering Halter Marine and Offshore Shipyard (STEHMO) when it broke away from the dock in the course of the passage of a chilly entrance, drifted throughout the Bayou Casotte channel and collided with the majority cargo vessel Akti. No accidents or air pollution have been reported.
As a results of the collision, the VALARIS DS-16 sustained injury to the riser dealing with system, deck fittings, switch hose-reel system, walkways and platforms, and different gear on board. A bulwark panel was deformed on the starboard facet, and insets on the facet shell plating and port stern have been additionally famous. Divers discovered no injury to the underwater portion of the hull throughout an underwater inspection. Damages have been estimated at $4.2 million.
The Akti sustained injury to the starboard-side bridge wing, handrails, deck coaming, facet shell plating, and lights. Damages have been estimated at $778,000.
STEHMO estimated the associated fee to interchange bollard 6 at its facility at $20,000. The bollard was not recovered from the channel after it broke away. There have been no reported damages to Chevron dock No. 6 the place the Akti was moored.
At the time of the incident, the drillship’s mooring strains have been positioned on six bollards on the pier on the STEHMO Shipyard (since acquired by Bollinger Shipyards and now named Bollinger Mississippi Ship Repair). During robust winds of 30-40 knots, one of many bollards broke free at its base and was pulled off the pier into the water. The snapped bollard secured the VALARIS DS-16’s 4 bow strains and a semisubmersible rig’s two stern strains.
Ultrasonic thickness exams carried out after the breakaway indicated there was deteriorated metal on the decrease portion of a number of bollards. Several bollards additionally confirmed indicators of exterior corrosion and wastage. In addition, the entire bollards utilized by the VALARIS DS-16 had been modified from the unique 1997 design and vertical parts added to every to accommodate extra strains.
“Investigators found that although each of the bollards used by the VALARIS DS-16, including bollard 6, was stenciled with a ‘300T’ marking, likely to indicate they could safely sustain a working load of up to 300 tons, there were no records of any pull tests that could confirm this stenciled safe working load,” says the NTSB report. “Additionally, there were no records of any modifications to the bollards, nor tests, inspections, or maintenance conducted on the bollards, with the exception of a bollard pull test for a tugboat that resulted in a load of 154.5 metric tons (170.3 tons) applied to an unknown bollard in December 2020. Further, all the bollards used by the VALARIS DS-16 had been modified from the original 1997 design, and vertical components (for which there were no engineering records) were added to each of the bollards to accommodate more lines. The bollard pipes’ overall height increased from just over 2 feet (26 inches) to anywhere from about 4 to 7 feet—about 2 to 5 feet higher than originally designed—with additional horns for mooring lines added well above the height of the horns on the original design. The additional horns allowed for mooring lines to be placed higher on bollards than planned for in the original design. As the height of a bollard (or its horns) increases, the horizontal or up-leading pull on the upper portion of the bollard significantly increases the moment of force applied to the base of the bollard.5 Therefore, bollard 6—and many of the other bollards used to secure the VALARIS DS-16’s mooring lines—were likely incapable of sustaining the working loads of their original design.”
The NTSB decided the possible reason for the drillship breakaway and subsequent collision with the cargo vessel was the failure of one of many shipyard’s mooring bollards—which had been modified to extend its top to accommodate extra strains—used to safe the VALARIS DS-16’s bow mooring strains to a pier, throughout a chilly entrance with robust winds.
The NTSB says the shipyard has changed 10 of the 14 bollards on the pier, with plans to interchange an eleventh bollard by the tip of March 2023. Shipyard managers have begun evaluating the protected working load of the brand new bollards and are scheduling a pull check utilizing a tugboat.
“As a result of continuing increases in vessel size and sail area, bollards that were previously sufficient may not have adequate capacity to moor larger vessels,” the report stated. “There are currently no U.S. Coast Guard or Occupational Safety and Health Administration regulatory requirements for facilities to inspect and verify loading capacities of bollards at shoreside facilities. Bollards and associated pierside mooring equipment are vital equipment that must be capable of withstanding the tremendous forces that large vessels exert on them. Due to their exposure to seawater, bollards and associated pierside mooring equipment are at high risk for corrosion, which can significantly affect service life. The Coast Guard has recommended that facility owners and operators develop a routine inspection program for bollards and other mooring equipment.”
- Download the total report on the drillship breakaway HERE
