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Gas release from pipeline during diving operations

This information note supersedes the guidance currently contained within IMCA International Code of Practice for Offshore Diving (IMCA D 014).


IMCA published Information Note IMCA D 04/12, outlining the considerations and limitations for using surface swimming as an operational means to complete tasks.  Such operational tasks may include:
  • Inspection works of floating hoses;
  • Work in the splash zone area;
  • SBMs;
  • Floating hose works;
  • Other work tasks to be conducted on the surface.
Such work tasks are often conducted from a small craft or from the side of a barge/vessel.

Non-Use of Surface Swimming

Surface swimming should not be used where the requirement is for the diver to place his head underwater.

Planning and Considerations when using Surface Swimming

The following requirements should be considered in planning to carryout surface swimming operations and work scope:
  • Conduct a detailed risk assessment and ensure all actions are implemented;
  • Minimum team size – there must be a sufficient number of competent and qualified personnel to carry out the task; a minimum for 1 surface swimmer would be 5 persons (swimmer, tender of lifeline, standby swimmer, tender for standby swimmer and supervisor);
  • Personal equipment to be considered for use:
    • protective coveralls/wet suit/dry suit
    • gloves
    • helmet complete with securing straps
    • full body harness
    • lifeline
    • life jacket/buoyancy aids
    • personal locator beacon (PLB)
    • personal locator lights/head torch light (waterproof)
    • fins, booties
    • half mask
    • knife on a lanyard that can cut the tether if required should it be snagged
    • safety glasses (deck personnel as required)
    • hand-held radio (for use by support crew).
The above items should be required for the swimmer and standby swimmer accordingly. For emergency response and preparedness, the following must be available at the worksite location ready to use:
  • First aid kit/medical kit according to recommendations of the diving medical adviser/AED/oxygen giving set;
  • Stretcher;
  • Means to recover an injured swimmer from the water;
  • IMCA Diver Medic Technician (DMT) and or first aider trained in use of AED and Oxygen Providing.
If using a small craft as a support boat, trained and competent coxswain and crew must be used, and the following must be implemented:
  • When using outboard motor have propeller guards;
  • Suitable means to get in and out of the water;
  • Flares available;
  • Paddles available;
  • Bailer available;
  • Flag alpha used when swimmer is in the water;
  • Means to recover the swimmer safely;
  • Means to recover an injured swimmer;
  • Hand-held radio (for use by support crew).
Swimming operations can be physically demanding and the fitness of the proposed candidate to carrying out these tasks should be assessed as part of the job planning.


Surface swimming should be a daylight activity only; consideration with regards sea state, wave height, current and surface visibility and general weather conditions must be made.  While the surface swimmer is in the water, the swimmer must be attached to a lifeline secure on the swimmers harness by a lockable karribineer (or similar).  The lifeline is to be actively tended and its end secured to a fixed point at the tending position.  There shall be a lookout watching the location and positioning of the swimmer in addition to the swimmers tender at all times.  Consideration should be given to having support on standby in or on a fast rescue boat (FRC) or a lifeboat ready to deploy but not necessarily launched. A swimmer should not be deployed into or recovered from the water if the height or if the freeboard is greater than 1 meter without a dedicated means of recovery and specific risk assessment for deployment and emergency recovery. In the event that the surface swimmer is not able to stay on loaction to carry out his work task comfortably, or if the surface swimmer becomes submerged during his work task, the surface swimming operation must be immediately stopped and the swimmer recovered to a safe location out of the water.

Operational Planning

Prior to conducting a surface swimming operational task, a detailed risk assessment must be conducted and all mitigating factors implemented.  During the swimming operations, a look out will observe for approaching vessels, general sea state condition and any other factors identified in the risk assessment. If surface swimming from a DP vessel, the swimmers lifeline must be restricted in length available to the swimmer in line with IMCA umbilical management advice for diving from DP vessels (Diving operations from vessels operating in dynamically positioned mode (IMCA D 010)), to prevent the diver being able to approach within 15 metres of an identified hazard.  The rescue swimmer should have a lifeline which would allow their approach to a hazard zone to be 13 metres.  The allowable lifeline length of the rescue swimmer may further restrict the allowable lifeline length of the working swimmer if deployed or tended from a diferent location from the working swimmer. Emergency planning and implementation shall be a primary consideration with standby swimmer drills carried out prior to starting the actual work task, communications from any remote work site checked, recovery capability of an injured swimmer tested and operational and medical support available.

Operational Support

The swimmer should not have his reserve buoyancy reduced by carrying tools or work equipment.  If required, the swimmer should be supported in his tasks with an inflatable boat or floating tool kit with the tools and equipment available and, if appropriate for working at height as the tools may be dropped, connected to the floatation support and not the diver. Consideration should be given to providing magnets, clamps or other mechanisms to provide hand holds or tool holds to assist the swimmer in his task.  These holding devices should incorporate a weak link if used to connect a swimmer to a structure if there is any possibility whatever of relative movement between his tend point and the structure (for reference, see Diver attachment to structures by means of a weak link (IMCA D 058)).

Originally issued with the following reference(s): IMCA D 08/19

Safety Event

Published: 1 January 2004
Download: IMCA SF 01/04

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