Guidance on diving operations in support of subsea decommissioning and dismantlement projects

Subsea decommissioning and dismantlement activities present a distinct and increasingly prevalent set of hazards for commercial diving operations. Unlike construction or inspection, repair and maintenance (IRM) work, these projects are characterised by ageing infrastructure, incomplete or inaccurate historical records, and rapidly changing conditions once installations enter cessation of production. 

This guidance has been developed to raise awareness of these challenges and to support IMCA Members in managing the risks associated with diver involvement in subsea decommissioning and dismantlement. The document highlights that incidents during decommissioning are frequently linked to assumptions about asset condition, reliance on outdated documentation, and inadequate transfer of historical information between asset owners and contractors. It emphasises the need for a dynamic approach to risk assessment, recognising that conditions often differ significantly from those anticipated during project planning. Robust verification processes, including as found surveys and a strong safety culture that encourages challenge and stop work authority, are essential.

Effective Management of Change (MOC) is identified as a critical control. Experience from major projects demonstrates that changes to scope, methodology and equipment are common and, if not systematically managed, can escalate rapidly into high potential incidents. The guidance therefore reinforces the importance of disciplined MOC procedures, clear communication and shared understanding across all parties.

The document also addresses key hazard areas specific to decommissioning, including subsea cutting techniques, stored energy, residual hydrocarbons, contaminated waters, naturally occurring radioactive materials (NORM) and lifting operations involving degraded or modified structures.

By drawing on real incident experience and existing IMCA guidance, this document aims to assist diving contractors and operators in reducing diver exposure, challenging assumptions and improving safety performance during subsea decommissioning and dismantlement projects.