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Hyperbaric Evacuation Systems Interface Recommendations published by IMCA

Published on 4 February 2013

Proposals published by the International Marine Contractors Association (IMCA) in ‘Hyperbaric Evacuation Systems (HES) Interface Recommendations’ (IMCA D 051) seek to address the interface issues encountered when a diving contractor needs to remove its divers from a stricken facility by use of a hyperbaric rescue unit (HRU).

“This document is a ‘recommendation’ only,” explains Jane Bugler, IMCA’s Technical Director. “We would like to emphasise too that the proposed interface recommendation put forward in our new publication is for future builds, it is not written with the view to retrofit existing systems. What we have published has four objectives:

  • To plan for the future;
  • To provide drawings and technical data that will support all interested parties;
  • To recognise and reflect current good practice;
  • To gain recognition and total world-wide acceptance.

“The ultimate objective is that ‘Every HRU will be able to mate with every DSV (diving support vessel) or HRF (hyperbaric reception facility) of any class anywhere in the world’,” she adds. “It is recognised that this particular objective might not be met for 30 years until non IMCA D 051 compatible, DSVs, barges and HRFs in use today have reached the end of their service life.”

The guidance document contains a number of drawings. However the drawings containing detailed engineering design information are also available on the IMCA website for download in .STP and .DWG formats

The new publication does not seek to address safety, risk assessments, planning, or general equipment maintenance issues. These are addressed in the main body of IMCA’S ‘Guidance on hyperbaric evacuation systems’ (IMCA D 052).

Looking back In the 1970s a system was introduced in the North Sea by a US diving company (IUC) for the evacuation of an injured diver from offshore in an emergency, while still under pressure. This comprised a single diver titanium chamber that was transported offshore by helicopter along with a larger chamber capable of taking up to four men.

The single chamber was fitted with 600mm (the commonest size in use at that time) flange and clamp. Over the years that followed many diving systems in the North Sea had one of their living chambers fitted with a compatible flange to accept this IUC chamber. This arrangement became considered the informal ‘standard’.

Over time as the industry matured and diversified, the use of the informal ‘standard’ diminished and in many areas was superseded by larger units more suited to operational demands; these changes also more closely reflected the genetic growth of the population over the last generation.

“The development of a ‘standard’ approach was very successful for the IUC flange in the North Sea,” says Jane Bugler. “A similar approach today would clearly be desirable for the future of hyperbaric evacuation within a global marketplace. It is generally agreed that a common interface recommendation that will permit successful hyperbaric evacuation without commercial, geographical or technical constraint would be of great benefit.”

Available online The new recommendation document can be downloaded by members and non-members alike free of charge from the IMCA website at and additional printed copies are available to members at £5.00 (plus delivery charge where applicable) and £10.00 for non-members via the website, from [email protected] or from IMCA at 52 Grosvenor Gardens, London SW1W 0AU, UK. Tel: +44 (0)20 7824 5520; Fax: +44 (0)20 7824 5521.