Reference material based on 'best industry practice' and the historical experience of a wide range of onshore and offshore disciplines dealing with issues associated with concrete mattresses has been brought together in Guidelines for Diver and ROV Based Concrete Mattress Handling, Deployment, Installation, Repositioning and Decommissioning (IMCA D042 Rev 1 / IMCA R016) published by the International Marine Contractors Association (IMCA).
"This guidance document was originally prepared under the direction of the IMCA Diving Division Management Committee," explains Jane Bugler, IMCA's Technical Director. "This revision has been updated by the Remote Systems & ROV Division Management Committee to include reference to the use of ROVs in mattress handling."
During the 1970s, the first pipeline support and stabilisation mattresses were installed subsea during offshore oil and gas operations. The design and composition of these early mattresses was very basic as they were essentially large canvas bags filled with a bituminous material mixed with aggregates. The first concrete mattresses were introduced in the early 1980s and evolved to become mould produced mattresses that continue to be used for protection, support, separation and stabilisation.
Design and specification, load-out, mobilisation, over-boarding, deployment, installation, re-positioning, decommissioning and recovery are all covered in the 24-page document, as is the use of 'roll out anti-scour fronded' mattresses and the associated safety and environmental issues, and in addition addresses ROV-only operations beyond diver depth, or for other reasons where divers are not suitable or available. It also includes useful tick box checklists to provide safety awareness during mattress handling operations.
Printed copies of Guidelines for Diver and ROV Based Concrete Mattress Handling, Deployment, Installation, Repositioning and Decommissioning cost £2.50 for IMCA members and £5.00 for non-members (plus 20% for delivery outside Europe). Orders can be placed via the IMCA website at www.imca-int.com, through publications[at]imca-int[dot]com and from IMCA at 52 Grosvenor Gardens, London SW1W 0AU, UK. Tel: +44 (0)20 7824 5520; Fax: +44 (0)20 7824 5521.