Extended Operational and Trade Vocabulary

Saturation Diving and Offshore Diving Operations glossary

The commercial-diving vocabulary: abandonment lines and severed umbilicals, absolute pressure and diver acclimatization, saturation-system and diving-bell operation, gas-mixture and partial-pressure management, decompression schedules, and the surface-supplied and life-support terms. Grounds each term in the diving physiology, the decompression theory, or the saturation-diving operation it belongs to.

367 defined terms.

Showing 250 on this page (page 1 of 2).

A

AAUS: American Academy of Underwater Sciences, the US scientific diving standards organization.
Abandonment Line: Emergency line used by a diver to ascend if the umbilical is severed.
Absolute Pressure: Total pressure on a diver including atmospheric and hydrostatic components.
Acclimatization: Physiological adjustment of a saturation diver to elevated ambient pressure.
ACoP: Approved Code of Practice issued by the UK HSE for commercial diving operations.
ADCI: Association of Diving Contractors International, the US commercial diving trade body.
ADCI Consensus Standards: Reference document defining minimum US commercial diving practice.
Adiabatic Heating: Temperature rise in chamber gas during rapid compression.
Aft Moonpool: Vessel opening near the stern through which the diving bell is launched.
Air Compressor: Reciprocating or screw machine that delivers compressed air for starting, control, service, and instrument duties.
Air Diver: IMCA category of diver qualified for surface-supplied air work to 50 m.
Air Diving: Surface-supplied diving to about 50 metres, standard for shallow salvage and survey.
Air Range: Depth band, 0 to 50 m, where breathing air remains within acceptable narcosis limits.
Aladin Gauge: Brand of decompression computer occasionally referenced in commercial work.
Alarm Matrix: Annunciator panel in a saturation control room listing chamber faults.
Alpha Flag: International Code flag "A" indicating "diver down, keep clear."
Altitude Diving: Diving above sea level requiring modified decompression profiles.
Ambient Pressure: Hydrostatic pressure at the diver's working depth.
Analox: UK manufacturer of gas analysis instrumentation used in saturation systems.
Analox DR 800: Diver gas reclaim analyzer monitoring oxygen and carbon dioxide.
Analyzer Calibration Gas: Certified gas mixture used to span and zero analyzers.
AODC: Association of Offshore Diving Contractors, a predecessor body to IMCA.
Approved Code of Practice: Statutory guidance under UK Diving at Work Regulations 1997.
Arterial Gas Embolism: Injury caused by gas bubbles entering arterial circulation, often from breath-hold ascent.
Aspirated Hat: Diving helmet with free-flow oxygen built for treatment of contaminated diver casualties.
Atmospheric Diving Suit: One-atmosphere articulated suit such as the JIM or Newtsuit.
Auto-Lock: Chamber lock that opens only after pressure equalization is verified.

B

BABS: Built-in emergency Breathing Apparatus System inside saturation chambers.
Backup Bellman: Stand-by diver inside the bell prepared to recover an incapacitated diver.
Bailout: Independent emergency breathing supply carried by every working diver.
Bailout Bottle: Cylinder, typically twin 7-liter steel, mounted on the diver's harness.
Bangkok: Operating base of Mermaid Maritime Public Company Limited.
Bar: Shoal at a harbor entrance.
Bell: Pressurized capsule transporting saturation divers between the system and worksite.
Bell Bounce: Short-duration bell dive without entering full saturation, used for one-off deep tasks.
Bell Cursor: Guide frame that constrains the bell during launch and recovery through the splash zone.
Bell Diver: IMCA-qualified diver competent to lock out of a closed bell.
Bell Diver Trainee: Provisional grade undergoing supervised closed-bell experience.
Bell Handler: Deck crew member operating winches during bell launch and recovery.
Bell Mating Clamp: Hydraulic clamp securing the bell to the trunking flange.
Bell Run: Single excursion of the bell from the system to the worksite and back.
Bell Trunking: Vertical tube connecting the bell mating flange to the saturation system.
Bellman: Standby diver inside the bell tending the working diver's umbilical.
Bends: Colloquial name for Type 1 decompression sickness affecting joints and skin.
Bibby Offshore: UK diving contractor acquired by Rever Offshore, later part of Mermaid Subsea Services.
Bibby Polaris: 117 m DSV operated by Bibby Offshore in the North Sea.
Bibby Topaz: 105 m DSV operated by Bibby Offshore for IRM work.
Biomarine: Manufacturer of self-contained rebreathers used in commercial bailout sets.
Blackpool: Site of The Underwater Centre Fort William's predecessor diver training operations.
Blowdown: Removal of concentrated boiler water to control TDS, performed as bottom or surface blowdown.
BOKA Atlantis: Boskalis Subsea Services DSV.
BOKA Falcon: Boskalis Subsea Services DSV used for IRM operations.
Boskalis Subsea Services: Dutch subsea contractor operating BOKA-class DSVs.
Bottle Bank: Manifolded array of high-pressure gas cylinders feeding the system.
Bottom Time: Elapsed time from leaving the surface until commencing ascent.
Bottom Timer: Mechanical or electronic device recording elapsed bottom time.
Bounce Dive: Surface-supplied or bell dive without entering saturation.
Bourdon Tube: Mechanical pressure-sensing element in chamber depth gauges.
Breathing Apparatus: Generic term for any device delivering a controlled gas mixture to a diver.
Breathing Loop: Closed gas path through a rebreather or bell reclaim system.
Buhlmann ZH-L16: Tissue-compartment decompression algorithm developed by Albert A. Buhlmann.
Built-in Breathing System: Overhead mask system in chambers supplying treatment gas independently of chamber atmosphere.
Burst Disc: Pressure relief safety device fitted to high-pressure gas storage.
Byford Dolphin: Semi-submersible drilling rig where four divers were killed in a saturation system explosive decompression on 5 November 1983.

C

Cable burial: Protective trenching of subsea cables for tidal, wave, and floating solar export systems to reduce snag risk from fishing gear.
Calibration Cell: Reference oxygen sensor against which working sensors are compared.
Carbon dioxide scrubber: Lime or amine bed inside CA unit removing excess CO2 from cargo respiration.
Cascade System: Manifold arrangement allowing sequential discharge of gas bottles.
CCC: Consolidated Contractors Company, parent of CCC Marine Services.
CCC Marine Services: Cyprus-headquartered subsea construction and diving contractor.
CDB Subsea: Chinese state-owned subsea construction division with diving capability.
Central Control Room: Compartment from which the Saturation Control Supervisor manages the dive.
Certificate of Medical Fitness to Dive: Document issued by a Diving Medical Examiner.
Chamber Atmosphere: Heliox, trimix, or air mixture maintained in a habitat at storage depth.
Chamber Operator: Technician qualified to control surface decompression chambers.
Closed Bell: Pressurized SDC capable of transferring divers under pressure to the surface system.
Closed Bell Diver: IMCA-qualified diver trained for lockout from a closed bell.
Closed Circuit Rebreather: Apparatus that recycles exhaled gas after scrubbing CO2.
Closed Diving Bell: Synonym for closed bell, distinguishing from open wet bells.
CO2 Scrubber: Canister using soda lime or lithium hydroxide to remove carbon dioxide.
Coflexip: Brand-origin term for flexible bonded pipe; now TechnipFMC.
Cold Shock: Cardiovascular response to sudden immersion in cold water.
Comex: French diving contractor that conducted the Hydra series experimental dives.
Compression Rate: Speed at which chamber pressure is increased during blowdown.
Conduct of Operations: PCASP operational document defining team behavior, communications and engagement procedures.
Confined Space Diving: Operations in flooded tanks, culverts, or vessels with restricted egress.
Construction Diving: Subsea fabrication, welding, and installation by divers.
Construction Support Vessel: General term for CSV; subsea installation/IRM duties.
Continuous Gas Analysis: Real-time monitoring of chamber and bell atmospheres.
Coxswain: Person in charge of a survival craft or rescue boat, certificated under STCW VI/2.
CP Probe: Cathodic protection probe used by divers to measure structure potentials.
CSV: Construction support vessel.
CTC Marine Projects: UK trenching contractor, now part of DeepOcean.

D

Daughter Craft: Small launch carried by a DSV for nearshore tasks.
DCBL: Dive Council UK, an industry diver welfare and standards forum.
DCS: IMO Data Collection System on fuel oil consumption, MARPOL Annex VI, cross-referenced with SOLAS chapter requirements.
DCS Type 1: Pain-only decompression sickness affecting joints, skin, and lymphatic tissue.
DCS Type 2: Neurological or cardiopulmonary decompression sickness requiring urgent recompression.
Decompression: Controlled reduction of ambient pressure to allow inert gas off-gassing.
Decompression Chamber: Surface chamber for treatment or surface decompression of divers.
Decompression Computer: Wrist or panel-mounted device calculating decompression obligation.
Decompression Profile: Schedule of stops and ascent rates for a given exposure.
Decompression Schedule: Tabulated stop depths and times for a planned dive.
Decompression Sickness: Diving condition unrelated to IMDG, listed only to flag MFAG coverage of compressed gas exposures.
Decompression Stop: Defined depth at which the diver waits to off-gas before continuing ascent.
Decompression Table: Tabular set of schedules such as US Navy Air or DCIEM tables.
Deep Constructor: TechnipFMC heavy construction vessel.
Deep Discoverer: TechnipFMC subsea construction vessel.
Deep Energy: TechnipFMC 194 m rigid pipelay vessel commissioned 2014 with diving capability.
Deep Inspector: TechnipFMC IRM and survey vessel.
Demobilization: Removal of a diving spread from a vessel after the project.
DESIGN: Diving Equipment Systems Inspection Guidance Note, IMCA D 023.
Differential Pressure Hazard: Hazard from divers working near intakes or breached compartments.
Diving at Work Regulations 1997: UK statutory instrument governing commercial diving.
Diving Bell: Pressurised chamber for transferring saturation divers to underwater work sites.
Diving Doctor: Physician trained in diving and hyperbaric medicine.
Diving Medical Examiner: Doctor certified to examine divers for fitness to dive.
Diving Medical Technician: Onshore or offshore technician trained in hyperbaric first aid and chamber operation.
Diving Operations Manual: Vessel-specific document defining procedures for the spread.
Diving Personnel: Collective term for divers, supervisors, technicians, and support crew.
Diving Plant: Equipment forming a diving system, subject to certification under IMCA D 045.
Diving Project Plan: Pre-mobilization document describing scope, hazards, and controls.
Diving Spread: Complete assemblage of equipment for an offshore diving operation.
Diving Superintendent: Senior shoreside or vessel-based manager responsible for diving operations.
Diving Supervisor: Person in direct charge of a single dive at the control panel.
Diving Support Vessel: Purpose-built vessel housing a saturation system and dynamic positioning.
DMAC: Diving Medical Advisory Committee, an industry advisory body on diving medicine.
DMT: Diving Medical Technician.
Doppler Bubble Detection: Ultrasonic technique for monitoring venous gas emboli post-dive.
DP Class 2: Dynamic positioning notation required for most North Sea DSVs.
DP Class 3: Dynamic positioning notation with full redundancy including separated machinery spaces.
DPVOA: Dynamically Positioned Vessel Owners Association, a predecessor body to IMCA.
Drager: German manufacturer of breathing apparatus and rebreathers.
Drill Master: Drillship where divers were killed in a 1983 North Sea incident.
DSV: Dive Support Vessel, dynamically positioned platform for saturation diving operations.
DSV Bibby Sapphire: Former Bibby Offshore DSV.
DSV Skandi Achiever: Subsea 7 chartered diving and ROV vessel.
Dump Valve: Exhaust valve venting chamber gas during decompression.
Dynamic Positioning: Computer-controlled thruster station keeping for salvage and dive vessels.

E

Eight-Hour Rule: Operational standard limiting saturation bell runs.
Electrical Continuity: Test ensuring grounding integrity of saturation electrical systems.
Emergency Hyperbaric Evacuation System: Self-propelled or towed lifeboat carrying divers under pressure off a stricken DSV.
Emergency Life Support Package: Battery and gas reserve sustaining the EHES.
Entertainment Trunk: Sealed passage through which media is passed into the living chamber.
Excursion Limit: Maximum vertical distance a saturation diver may travel from storage depth.
Excursion Table: Tabulated allowable depth excursions for given storage depths.

F

FFM: Full face mask.
Fire Fighting Foam Compatibility: Requirement for foams used near hyperbaric chambers.
Fitness to Dive: Medical and physical certification status of a diver.
Flange Test: Pressure test on bolted joints inside hyperbaric piping.
Flow Restrictor: Device limiting handwash sink flow to a specified rate to conserve water without compromising hygiene.
Flush Filling: Topping a chamber with mixed gas while venting to maintain composition.
Foreign Gas: Any gas in the chamber atmosphere outside the prescribed mix.
Fort William: Site of The Underwater Centre, a UK commercial diver training school.
Forward Moonpool: Vessel opening near the bow used for ROV or auxiliary launch.
Free Flow Helmet: Open-circuit helmet with continuous gas supply, no demand valve.
Full Face Mask: Diving mask covering nose, mouth, and eyes with demand regulator.

G

Galeazzi: Italian manufacturer of historic standard diving dress helmets.
Gas Analysis: Measurement of oxygen, carbon dioxide, and inert gas fractions.
Gas Bank: Cylinder rack supplying breathing gases to the dive system.
Gas Mixing Panel: Manifold blending heliox and oxygen for chamber make-up.
Gas Reclaim: Recovery and re-use of exhaled helium after scrubbing.
Gas Reclaim Unit: Skid containing the compressor, scrubber, and storage for reclaimed gas.
Gas Storage: High-pressure cylinder banks holding helium, oxygen, and air reserves.
General Visual Inspection: Underwater inspection level performed by divers or ROVs.
Geotech G100: Portable infrared gas analyzer used in diving applications.
Glass Reinforced Plastic: GRP, used for non-metallic chamber components.
Gloves: Diver hand protection ranging from neoprene to hot-water heated types.
Guide Wire: Tensioned wire constraining the bell during launch.

H

Habitat: Welding or work enclosure isolating divers from open water.
Hard Hat: Heavy commercial diving helmet such as the Kirby Morgan 37.
HAZID: Hazard Identification workshop used in design and post-casualty review.
HAZOP: Hazard and operability study applied to diving system design.
Heated Suit: Diver suit circulating hot water for thermal protection.
Helideck: Flight deck on surface combatant sized for embarked helicopter.
Heliox: Breathing mix of helium and oxygen typically 95-98 percent helium for saturation.
Helium Recovery System: HRS, the closed-loop reclaim plant on a saturation DSV.
Helium Speech Unscrambler: Electronic device translating high-pitched heliox voice for surface listeners.
Helium Voice: Distortion of speech in heliox due to gas density and sound speed.
Helix Energy Solutions: US offshore well intervention contractor operating the Q-series vessels.
High Pressure Nervous Syndrome: HPNS, a neurological disorder appearing on heliox below about 180 m.
Hot Water Suit: Open-circuit diver suit supplied with heated water through the umbilical.
HPNS: High Pressure Nervous Syndrome.
HRS: High Risk Ship, see entry above.
HSE: UK Health and Safety Executive; offshore safety regulator UKCS.
HSE ACoP L103: Approved Code of Practice for commercial diving offshore.
HSE ACoP L104: Approved Code of Practice for inland and inshore commercial diving.
HSE ACoP L105: Approved Code of Practice for scientific and archaeological diving.
HSE ACoP L107: Approved Code of Practice for media diving.
Hydra Series: Comex experimental deep-dive program in the 1980s and early 1990s.
Hydra X: 1992 Comex onshore experimental saturation dive reaching 701 m simulated depth.
Hyperbaric Chamber: Pressure vessel for human occupancy used in treatment or saturation.
Hyperbaric Evacuation: Recovery of divers under pressure from a damaged DSV.
Hyperbaric Health Toronto: Canadian hyperbaric medicine clinic.
Hyperbaric Lifeboat: Self-righting lifeboat fitted with a pressurized chamber for divers.
Hyperbaric Medicine: Medical specialty using elevated pressure oxygen for treatment.
Hyperbaric Oxygen Therapy: HBOT, clinical use of oxygen at greater than atmospheric pressure.
Hyperbaric Welding: Welding inside a dry habitat at ambient diver pressure.

I

IMCA: International Marine Contractors Association; DP, diving, ROV guidance.
IMCA Audit: Common name for the IMCA DESIGN audit of a diving system.
IMCA D 014: International Code of Practice for Offshore Diving.
IMCA D 015: Mobilisation and Demobilisation of Diving Equipment Spreads.
IMCA D 023: Diving Equipment Systems Inspection Guidance Note, "DESIGN."
IMCA D 024: Code of Practice for Surface Supplied Mixed Gas Diving.
IMCA D 037: Code of Practice for Inshore Diving Operations.
IMCA D 044: Saturation Diving Practitioners' Workshop guidance.
IMCA D 045: Code of Practice for the Initial and Periodic Examination of Diving Plant and Equipment.
IMCA D 050: Minimum Quantities of Gas Required Offshore.
IMCA D 053: Saturation Diving for Decision Makers guidance.
IMCA Diving Division: Technical committee within IMCA setting diving standards.
IMCA Members: Subscribing contractor companies bound by IMCA codes.
In-Water Decompression: Decompression stops performed in the water rather than in a chamber.
Inland Diver: Diver category limited to inland and inshore work.
IRM: Inspection, repair and maintenance work, often via ROV.
Isobaric Counterdiffusion: ICD, simultaneous inward and outward movement of different gases across tissue at constant pressure.

J

James Fisher Marine Services: UK marine services group with diving and decommissioning capability.
Job Safety Analysis: Task-level risk assessment performed before diver lockout.
JONSWAP spectrum: Joint North Sea Wave Project spectral form.

K

Kirby Morgan 37: Widely used commercial diving helmet.
Kirby Morgan 47: Saturation-rated commercial diving helmet.
Kirby Morgan SuperLite 17: Earlier-generation commercial diving helmet.
Knock-Up Test: Function test of bell mating and seal integrity before a dive.

L

LARS: Launch and recovery system for ROVs, bells, and AUVs.
Lateral Loading: Side load on the bell during launch through the splash zone.
Launch Window: Sea state and weather envelope permitting safe bell operations.
Life Support Package: Reserve gas and battery package for emergency hyperbaric evacuation.
Life Support Supervisor: LSS, manager of saturation system life support during a project.
Life Support Technician: LST, operator of chamber gas, temperature, and humidity systems.
Lithium Chloride Scrubber: Adsorbent used to control humidity in chamber atmospheres.
Lithium Hydroxide: CO2 absorbent used in some diver bailout rebreathers.
Living Chamber: Pressurized accommodation in the saturation system for divers between bell runs.
Lockin: Re-entry of the diver into the bell from the water.
Lockout: Transfer of a diver from the bell into the water at pressure.
Loss of Communications: Alert phase triggered by unexplained communication failure with a vessel.
LSS: Life Support Supervisor.
LST: Landing Ship Tank, retired USN designation.

M

Maintenance Lock: Small lock used to pass tools and parts into pressurized chambers.
Make-up Gas: Replacement gas added to maintain chamber composition.
Mating Clamp: Hydraulic clamp connecting the bell to the trunking.
McDermott: US offshore contractor with limited offshore wind involvement; reference for context.
Medical Lock: Small lock used to pass medical supplies into pressurized chambers.
Mermaid Maritime: Bangkok-listed subsea services contractor.
Mermaid Subsea Services: Group encompassing Mermaid's diving and inspection operations.
Mixed Gas: Breathing gas containing inert components other than nitrogen.
Mixed Gas Diving: Surface-supplied diving on heliox or trimix, typically 50 to 100 m.
Mobilization: Installation and certification of a diving spread on a vessel.
Moon Pool: Vertical opening through a vessel hull for bell launch.
MSF1: Common reference notation for a 12-man saturation system.
MSF2: Common reference notation for an 18-man saturation system.

N

Narcosis: Nitrogen narcosis, the anesthetic effect of nitrogen at elevated partial pressure.