An unsecured anchor created eight holes in the hull of Floatel Superior during the night of 6-7 November 2012, causing water to enter two tanks and producing a list of about 5.8 degrees.

The facility was then lying on the Njord field in the Norwegian Sea, where Statoil is operator. A total of 336 people were evacuated by helicopter to other installations nearby.

No personal injuries were suffered among the 374 people on Floatel Superior as a consequence of the incident. In the PSA’s view, the position on board was handled well. Many good and well-considered decisions were taken during the incident, in strong winds and high waves.

The PSA resolved to launch an investigation into the incident.

Nonconformities

The investigation identified breaches of the regulations related to:

  • inadequately dimensioned bolsters
  • inadequate hull dimensioning to withstand unsecured anchors
  • inadequate protection of personnel from pennant wire
  • inadequate securing of anchors in bolsters
  • deficient logging of line tension
  • deficient safety equipment for lifeboat coxswains
  • inadequate documentation
  • Floatel Superiorwas operated beyond its design assumptions
  • deficient risk understanding and compliance with requirements.
  • Damage to anchor bolsters

The anchor which came loose punched holes in the hull and punctured two ballast tanks. In the PSA’s view, it is not unlikely that more tanks could have been punctured in unfortunate circumstances. The overall list could then have come close to the design limit of 17 degrees.

An anchor bolster (a steel structure intended to hold one or more anchors alongside the hull when not in use so that they do not damage the hull) lost three bracings on the incident night, following damage which had occurred and developed over time.

After this breakage, the remaining bolster components were unable to prevent the anchor from hitting the hull directly. The anchor was left hanging free, struck the hull repeatedly in heavy seas and made seven holes.

The eighth hole was created when a damaged part of the anchor bolster broke loose through fatigue cracking.

Damage in the early stages of development was also observed on the other bolsters.

In the PSA’s view, Flotel Superior had been damaged before being taken into use on the Norwegian continental shelf (NCS). This was caused by transporting it in higher waves than the operations manual and analyses permit. This damage has probably worsened in bad weather up to the incident night.

The incident is primarily the result of the design choices made, related to the fact that the anchors on Floatel Superior were stowed in bolsters when dynamic positioning was being used to keep the facility on station.

Inappropriate solutions identified include:

  • the anchors could not be adequately attached to the bolsters
  • the bolsters were not dimensioned for the loads to which they were exposed
  • the doubling plate[RG1] did not function as a weak structural element
  • the hull was not dimensioned to withstand blows from an anchor.

A general deficiency was cooperation between and understanding of the preconditions applied by different players when designing, constructing and operating the facility.

Orders

On the basis of the findings made during the investigation, the PSA has now issued Floatel International the following orders:

Pursuant to section 69 of the framework regulations on administrative decisions, see section 6 of the management regulations on management of health, safety and the environment, and section 15 of the management regulations on information, Floatel International is ordered to implement measures which ensure identification, registration and follow-up of conditions of significance for safety.

The grounds for the order are provided by chapter 5.1.9 of the investigation report.

Pursuant to section 69 of the framework regulations on administrative decisions and section 25 of the activities regulations on the use of facilities, Floatel International is ordered to establish the weather which Floatel Superiorhas been subject to, analyse the effect on the hull of having operated Floatel Superiorbeyond its design assumptions during transit, and establish which consequences this has for continued use of the facility. The grounds for the order are provided by chapters 3.2 and 5.1.8.

Pursuant to section 69 of the framework regulations on administrative decisions, section 22 of the management regulations on handling of nonconformities, see section 3 of the framework regulations on the application of maritime regulations, Floatel International is ordered to carry out a new assessment of compliance with the maritime regulations for structures and maritime systems. The grounds for the order are the nonconformities described in chapter 5.1, see also chapter 5.6.

Floatel International must take the initiative for a meeting to submit plans and methodology for complying with the orders. This meeting must take place no later than 15 May 2013.

The deadline for compliance with the orders and responding to the PSA is set at 15 September 2013.