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Maintenance of barriers for subsea facilities

In April and May 2018, we held a series of meetings with selected participants in order to gather knowledge about the maintenance of barriers for subsea facilities involved in the Norwegian petroleum activities. The companies which we followed up were Aker BP, Equinor, Shell, Subsea 7, Technip FMC, Oceaneering and Deep Ocean.


Subsea technology occupies an important place in present-day petroleum technology and its use is expected to increase in future developments. Experience and the results of RNNP (risk level in the Norwegian petroleum activity) analyses in recent years have shown that accident prevention in petroleum activities on the seabed is an area that warrants more attention. The companies must work on continuous improvement to safety and ensure the existence of measures to prevent and mitigate the risk of accidents under water. They must also have in place the necessary barriers for detecting, limiting and stopping undesirable incidents and accidents.

The objective of the meetings was to clarify whether maintenance practice for subsea facilities was being undertaken prudently. This entails giving the operators adequate oversight of the status and trends in status over time and helping ensure that information is used to prevent accidents and promote continuous improvement.

We focused particular attention on the maintenance of barriers for subsea facilities, and collected knowledge about and experience of this issue.

We placed special emphasis on processes for:

  • Identification of barrier functions, including control system
  • Condition monitoring, including functional testing of barrier functions
  • Classification of equipment and prioritisation of identified failures in barrier functions

Prudent maintenance practice also depends on management across the interface between operators and contractors. For this reason, we held meetings with both operators and contractors – the latter within equipment supply and/or the performance of maintenance.

Topics for the meetings

We asked the operators to give a presentation covering the following topics:

  • Which barriers are critical for identifying as rapidly as possible conditions and faults that may cause acute pollution
  • Which strategies and policies are defined for maintenance, testing and monitoring of these barriers
  • Consequence classification of systems and equipment that make up the subsea facility
  • What performance requirements are defined for technical, operational or organisational barrier elements
  • Activities for monitoring performance and technical conditions to ensure that developing or incipient failure modes are identified and rectified

The contractors were asked to cover the following topics:

  • What the maintenance contract covers
  • Which regulations are applied and why
  • Management system and bridging documents
  • Requirements for technical, organisational and operational competence
  • The management of the maintenance
  • Monitoring of the barriers’ performance and technical condition to ensure that developing or incipient failure modes are identified and rectified
  • Evaluation of maintenance effectiveness
  • Technical, operational and organisational challenges
  • The operator's follow-up of maintenance activities
  • Own follow-up of the contract

The results are summarised in the attached report.

Øyvind Midttun, press contact
Email: oyvind.midttun@ptil.no | +47 51 87 34 77