Deteriorated Bollard Caused Drillship Breakaway and Collision
A deteriorated bollard led to a Valaris drillship breaking away and colliding with a bulk carrier in Pascagoula, Miss. last year, the National Transportation Safety Board (NTSB) said Thursday.
On March 12, 2022, the mobile offshore drilling unit Valaris DS-16 was in the process of being reactivated at the ST Engineering Halter Marine and Offshore Shipyard (STEHMO) when it broke away from the dock in strong winds, drifted across the Bayou Casotte channel and collided with the bulk carrier Akti. There were no injuries reported for the 164 crewmembers and personnel on board the drillship or the 22 crewmembers on board the bulker, and there was no pollution reported. The total damage resulting from the breakaway was estimated at $5 million.
The drillship’s mooring lines had been placed on six bollards on the pier at the STEHMO Shipyard. During strong winds of 30-40 knots, with gusts 45-50 knots, one of the bollards broke free at its base and was pulled off the pier into the water. The snapped bollard secured the Valaris DS-16’s four bow lines and a semisubmersible rig’s two stern lines.
Ultrasonic thickness tests performed after the breakaway indicated there was deteriorated steel at the lower portion of several bollards. Several bollards also showed signs of external corrosion and wastage. In addition, all of the bollards used by the Valaris DS-16 were modified from the original 1997 design, and vertical components were added to each of the bollards to accommodate more lines.
As a result of the collision, the VALARIS DS-16 sustained damage to the riser handling system, deck fittings, transfer hose-reel system, walkways and platforms, and other equipment on board. A bulwark panel was deformed on the starboard side, and insets on the side shell plating and port stern were also noted. Divers found no damage to the underwater portion of the hull during an underwater inspection. Damages were estimated at $4.2 million.
The Akti sustained damage to the starboard-side bridge wing, handrails, deck coaming, side shell plating, and lighting fixtures. Damages were estimated at $778,000.
STEHMO estimated the cost to replace bollard 6 at their facility at $20,000. The bollard was not recovered from the channel after it broke away. There were no reported damages to Chevron dock no. 6 where the Akti was moored.
The shipyard has since replaced 10 of the 14 bollards on the pier, with plans to replace an 11th bollard by the end of March 2023. Shipyard managers have begun evaluating the safe working load of the new bollards and are scheduling a pull test using 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 said. “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.”