The International Marine Contractors Association (IMCA) has published new guidance designed to improve safety during subsea decommissioning and dismantlement projects, which could significantly benefit the Asutralian decommissioning industry given its relatively limited experience of large-scale dismantlement projects.
As offshore oil and gas assets around the world reach the end of their operational life, decommissioning activity is expected to increase significantly over the next decade. No more is this more so than in Australia, which is entering a sustained phase of decommissioning activity, as fields mature and infrastructure that has supported oil and gas production since the 1960s comes to the end of its productive life.
IMCA’s Guidance on diving operations in support of subsea decommissioning and dismantlement projects (IMCA D090) has been developed to help contractors, operators, and project teams better understand and manage the unique operational and safety challenges associated with dismantling ageing subsea infrastructure, which is creating an increasingly high-risk environment for commercial diving operations. Increased vessel activity, heavy lifting operations, subsea cutting, breaking containment, diver intervention and simultaneous operations taking place within restricted work areas all pose potential hazards.
Decommissioning projects frequently involve structures that were never designed to be removed. With ageing facilities, engineering records may be incomplete or inaccurate, and the actual subsea condition of assets can differ significantly from original drawings or assumptions made during project planning.
The IMCA warns that incidents during decommissioning are frequently linked to assumptions about asset condition or reliance on outdated information. The guidance therefore places strong emphasis on verifying “as found” conditions throughout the project lifecycle and ensuring effective transfer of historical information between all parties involved.
The document also recognises that conditions can evolve rapidly as dismantlement progresses, requiring continuous reassessment of hazards and control measures.
Particular emphasis is placed on the Management of Change (MOC) process, given that changes to scope, methodology, equipment, sequence of work or environmental conditions are common during decommissioning campaigns, and that failures to identify or properly manage those changes have contributed to a number of high-potential incidents.
The guidance reinforces the need for formal, disciplined MOC procedures supported by clear communication, documented verification processes, and a shared operational understanding across project teams.
It also suggests looking at alternatives to diver intervention such as remote systems or engineered alternatives wherever reasonably practicable.
Where diving operations are unavoidable, IMCA states they should only proceed with robust planning, verified information, clearly defined controls, and a safety culture that empowers personnel to question assumptions and exercise stop-work authority where concerns exist.The document also addresses a range of hazards commonly associated with subsea decommissioning activities, including subsea cutting techniques, lifting operations, residual hydrocarbons, stored energy, and contaminated environments.
Bill Chilton, Diving Manager at IMCA, said, “Subsea decommissioning and dismantlement activities present a distinct and increasingly prevalent set of hazards for divers. Where incidents have occurred, experience shows many could have been avoided through better planning, more rigorous verification of conditions, and disciplined management of change procedures.
“Many offshore structures now reaching the end of their operational life were installed long before dismantlement was ever considered. They were designed to operate, not necessarily to be removed safely decades later. That creates a very different risk profile for diving teams working subsea.”
The guidance is available through the IMCA Technical Library.
