The incident on the North Sea field occurred while filling (pressurising) a 3.4-litre nitrogen gas cylinder, which formed part of the fire extinguishing system on the platform and was to be pressurised to 200 barg using a booster pump.

During this operation, the cylinder burst and broke into several pieces. A three-strong work team was present, and two of its members were seriously injured.

Actual and potential consequences

The actual consequence of the incident was that two people were badly hurt, and one suffered life-threatening injuries. Both spent a long period on sick leave.

Heimdal ceased production the day after the incident, and remained shut down for 5.5 days.

Under slightly different circumstances, the incident had the potential to become a fatal accident.

Direct and underlying causes

The direct cause of the incident was that the nitrogen gas cylinder is likely to have been exposed to a significantly higher pressure than it was designed to cope with.

The PSA investigation found that the underlying causes related to:

  • lack of barriers against overpressure
  • risk of using the pump had not been dealt with
  • expertise and quality in the underlying preparations for the work operation
  • lack of documentation
  • training
  • the system design.

Technical examination

(Updated 21 September 2020): DNV GL AS was commissioned to study the booster pump/compressor and nitrogen gas cylinder involved in the incident on Heimdal. This work was completed in August 2020.

The purpose of this examination was to clarify the equipment’s function and actual capacity, while simultaneously describing any possible impairments it might have suffered before the event.

Regulatory breaches

The investigation has identified serious breaches of the regulations, with nonconformities found in the following areas:

  • inadequate safety-clearance of activities
  • lack of barriers against overpressure
  • lack of competence
  • inadequate planning and risk assessment
  • lack of procedures and routines.

Notice of an order

The investigation has identified serious breaches of the regulations, and the PSA has now given Equinor the following order.

Pursuant to section 69 of the framework regulations on administrative decisions, see sections 30 and 21 of the activities regulations on safety clearance of activities and on competence respectively and section 15 of the management regulations on information, you are ordered to:

  • ensure that activities of this types are planned and executed in such a way that those who participate in the activity are not injured and that the probability of human error is reduced. That involves taking the measures required to ensure adequate competence in using this type of type of tool, and ensuring that the risk is known in all relevant parts of the organisation. See sections 9.1.1, 9.1.3 and 9.1.4 of the report
  • ensuring that knowledge about and lessons learnt from the incident are communicated in a systematic way to the whole company.

The deadline for compliance with the order is 15 August 2020. We must be notified when the order has been complied with.

The investigation report also contains identified nonconformities in addition to those which form the basis for the notice of an order, and the PSA has asked Equinor to explain how these will be dealt with. The company has been given until 15 June 2020 to respond.