Commercial Diving Umbilical Connectors -- IMCA D 023 Standard Explained

The IMCA D 023 ("Guidance on Umbilical Connectors") document published by the International Marine Contractors Association (IMCA) provides the industry's primary reference for commercial diving umbilical connector interface requirements. Understanding this document is essential for any engineer specifying connectors for diving helmets, hot-water suits, communication systems, and surface-supplied diving umbilicals.

What Is IMCA D 023?

IMCA D 023 is a guidance document -- not a mandatory standard -- that establishes interoperability requirements for commercial diving umbilical connectors. Its primary goal is to ensure that a diver's umbilical from one manufacturer will mate with the helmet, bell, or deck equipment from a different manufacturer during a saturation or surface-supplied diving operation.

The document covers:

• Physical interface dimensions for male and female connectors (plug and receptacle)
• Contact assignment and pin-out for communications, power, and gas circuits
• Pressure ratings for the assembled connection
• Test methods for validating connector performance
• Marking and identification requirements

The Burton/Eaton Connector Geometry

IMCA D 023 references the connector geometry originally established by Burton (now Eaton Burton). The Burton connector has been the de-facto standard in commercial diving for over 40 years. Its defining features:

• 3-contact design: two power/comms pins and one earth (ground)
• Bayonet-type quarter-turn locking ring -- mates/de-mates with gloved hands underwater
• Low mate force (<15 N insertion) for diver operability at depth
• 316L stainless steel shell with neoprene/polyurethane overmould on cable entry
• Rated to 300 m depth; variants to 600 m for saturation diving

RV Power Group's RMG and RMK series connectors are fully intermateable with Burton/Eaton connectors per the IMCA D 023 interface geometry. A Burton male plug mates directly with an RMG female receptacle, and vice versa.

Key Electrical Requirements Under IMCA D 023

Hydrostatic Testing per IMCA D 023

IMCA D 023 requires that connectors be pressure-tested before deployment. RV Power Group's standard test protocol exceeds IMCA D 023 minimum requirements:

1. Fill connector assembly with freshwater
2. Apply hydrostatic pressure to 1.5x maximum rated depth pressure (equivalent to 450 m for a 300 m-rated connector)
3. Hold for 15 minutes minimum
4. Inspect for leakage -- zero tolerance
5. Measure insulation resistance post-test (>500 M-ohm)
6. Record pressure, test date, and serial number on test certificate

Saturation Diving Considerations

For saturation diving operations (where divers live at pressure in a bell/habitat system), connector requirements are more stringent:

• Hyperbaric He/O2 atmosphere: Helium is a small molecule that permeates elastomers more readily than nitrogen. EPDM or FFKM O-rings are preferred over Buna-N in saturation environments.
• Helium absorption/decompression cycles: O-rings may be damaged by decompression if internal trapped voids expand rapidly. Use low-void-fraction polyurethane potting on cable entry.
• Extended deployment: Saturation connectors may be in the pressurised environment for 28+ days. Design for compression set at elevated pressure over this period.

Specifying IMCA D 023-Referenced Connectors

When writing a specification for commercial diving umbilical connectors, reference the document as follows:

"Connector interfaces shall conform to the geometry and test requirements of IMCA D 023 and shall be intermateable with Burton/Eaton series 3-pin diving umbilical connectors. Hydrostatic test certificate per IMCA D 023 Section [X] shall be provided with each connector assembly."

RV Power Group supplies printed hydrostatic test certificates with every RMG/RMK connector, identifying the test date, applied pressure, duration, and test result. These documents are accepted by diving supervisors and vessel operators complying with IMCA codes of practice.

For IMCA D 023-referenced connector quotations and technical data sheets, contact [email protected].