Combined operations (ComOps) ALARP assessment

Minimizing intervention time by safely maximizing personnel numbers


The customer challenge was for timely completion of a major construction campaign using increased manning during a ComOps with an accommodation unit (Flotel). Deviations (manning, duration, operational status of the host platform) throughout the project led to the requirement for several ALARP (as low as reasonably possible) demonstration cases needing to be completed over short timescales.

DNV GL solution

Structured ALARP assessment based on the Oil & Gas UK Risk-Based Decision Making Framework and DNV GL Guidance on ComOps Manning consisting of:

  • HAZID – Identification of additional, or changes to existing hazards and safeguards
  • Impact on Flotel – CFD and free field modelling of flammable gas, smoke and overpressure hazards
  • Quantitative risk assessment (QRA) – Assessment of the tolerability of increased risk
  • Prevention of Fire and Explosion and Emergency Response (PFEER) – Suitability of ComOps specific EER issues, including Alternative Muster Points, bridge impairment, impact of TEMPSC capacity on determination of maximum manning.

Outcome and benefits

The assessment allowed the operator to safely maximize the number of personnel on board and thus minimize the intervention time and cost. The process demonstrated that risks are ALARP both to the regulator, operator and Flotel contractor.