Professional diving equipment goes through a documented regime of checks: daily user checks, periodic maintenance at an authorised workshop, and statutory testing on cylinders and lifting gear. Equipment without an up-to-date record is treated as out of service, even if it works.
In commercial diving there's a line that gets repeated in workshops: equipment doesn't fail, it's allowed to fail. That's a bit unfair to the mechanics of things, but it points at something true. Almost every equipment failure that ends in an incident has a skipped maintenance, an overdue inspection or a checklist done from memory behind it.
The industry answers that with an inspection regime that can look excessive until you remember that the kit in question is the only thing separating a person from an environment they can't breathe in. This article goes through how that's organised, without getting into specific intervals, which depend on the manufacturer, the country and the applicable scheme, and which should always be checked against the official source.
Three levels of control
The user check
This is done before every use and carried out by the diving team itself. It isn't maintenance: it's a functional check. You confirm that everything is there, that everything moves the way it should, and that there's no visible damage.
Its value lies in the discipline. A check done with a list in hand and without rushing catches things a trained eye misses when it moves fast: a loose screw in the visor, a twisted clamp, a corroded comms connector.
Periodic maintenance
This is set by the manufacturer's manual and carried out by trained personnel, using original parts and following the procedure for that specific model. It includes replacing wear items, verifying performance and running functional tests that are measured, not estimated.
There's a classic temptation worth naming here: the equivalent part. A seal that looks the same, a spring that fits. In a surface-supplied regulator, those substitutions change the breathing performance of the assembly in ways that don't show up until a diver has to breathe hard at depth.
Statutory testing
Some items are subject to inspections with their own regulatory basis, separate from whatever the manufacturer says. Pressure vessels — cylinders, gas panels — have their own regime of periodic inspection and testing. Lifting gear has its own. Personal protective equipment has its own. All of them generate certificates that must be kept and be ready to show.
What gets checked on each item
The helmet
El casco is the most critical item and has the strictest regime. Checks cover the regulator's performance, the inlet non-return valve — which stops the diver's airway from decompressing suddenly if the supply is cut — the emergency valve, the seal of the assembly, the condition of the visor, and the head and neck fastening system.
Whether a helmet is well maintained can't be judged by looking at it, and that's exactly why the documented record exists. A helmet with no history is an unknown helmet.
The umbilical
El umbilical carries the gas supply, communications, depth line and strength member together. It's inspected visually along its full length for abrasion, cuts and crushing, the terminations are checked, and the strength of the strength member is verified according to the applicable procedure.
Umbilical damage almost always turns up in the same places: the edge of the gunwale, points where it rubs against structure, and the connection area. Knowing those spots and giving them extra attention is part of the trade.
The panel and gas supply
The gas panel brings together gauges, valves and the switching between sources. The gauges are checked against a reference, the valves are checked, and the switch to reserve is confirmed to work with the diver in the water, not just on paper. On top of that, the quality of the air or mix supplied is analysed periodically, because a compressor with a bad intake introduces contaminants that no gauge will pick up.
Lifting gear
Slings, shackles, hooks, winches and anything that carries load has individual identification, a certificate and an inspection record. The practical rule is simple: if it can't be identified, it can't be certified, and if it can't be certified, it doesn't get used. In operations with suspended load underwater this discipline isn't box-ticking, because the diver works directly under the load far more often than anyone would like.
The recompression chamber
This is a pressure vessel with life support, and its inspection regime reflects that: shell testing, checking valves and penetrations, checking the oxygen supply and communication system, and a full functional test. A chamber that hasn't been used for months isn't a chamber that doesn't need checking; it's exactly the one that needs the most attention before an emergency.
Communications
The voice communication system is often treated as an accessory, but it's actually a safety item: it's the channel through which the supervisor knows how the diver is doing. Checks cover the helmet's headphones and microphone, the wiring inside the umbilical, the comms box and its power supply, and the backup system provided for when the main one fails.
Corrosion on the contacts is the most common problem and the easiest to prevent with systematic rinsing and drying after every use. A diver who's hard to hear isn't an inconvenience: under the applicable procedure it can mean a dive that has to be aborted.
The part people underrate: the record
Equipment that's been checked but has no record counts as equipment that hasn't been checked. That statement is jarring at first, but it's the logic of any regulated industry: what can't be demonstrated didn't happen.
That's why serious companies keep an inventory with a record card for every item, its history and its expiry dates, and it's why one of the things a diver can check when weighing up a new contractor is whether that system exists and is kept current. It's a fairly reliable indicator of how the outfit works overall, far more so than how shiny the kit looks.
The suit and thermal protection
The suit gets checked less than it should because it isn't seen as safety equipment, and yet its failure has direct consequences. On a drysuit, checks cover the zip, cuffs, neck seal, inflation and dump valves, and the general seal; on hot water suits, they also cover the condition of the hoses, the internal distribution and the supply temperature.
That last point deserves special attention. A failure in the water temperature control on a hot water suit isn't a minor annoyance: it can cause burns or, at the other extreme, rapid heat loss. That's why the heating system has its own controls and alarms, and checking it is part of preparing any dive that uses one.
The culture around maintenance
Documentation systems exist everywhere; what varies between companies is whether they're used or just filled in. There are two fairly reliable signs that a system is actually alive.
The first is that the records contain awkward entries: items withdrawn from service, checks brought forward because someone spotted something odd, minor incidents documented. A history where everything always comes out fine is a history nobody actually looks at.
The second is how the organisation reacts when a diver pulls a piece of equipment out of service. If the response is to fix the problem and thank the diver for flagging it, the system works. If the response is to argue over whether it was really necessary, the system is broken no matter how much paper is in the file.
This last point is worth stating plainly, because it's where maintenance stops being a technical matter and becomes a cultural one. Written procedures don't stop anyone diving with doubtful equipment: what stops it is that pulling that equipment out of service carries no personal cost for the person who does it.
Shared equipment and personal equipment
In commercial diving most of the kit belongs to the company, not the diver, and that brings a dynamic worth recognising. A helmet used by several people across different shifts tends to end up with nobody feeling responsible for it, and small details — a seal that needs ordering, a screw that's a bit tight — keep getting left for the next person.
The fix that well-run teams apply is assigning named responsibility: each helmet has an assigned user for the campaign, or a person responsible who does the full check and signs it off. It isn't extra bureaucracy; it's how small things get sorted while they're still small.
What you can do
Three concrete things, in order of importance.
Learn the manual for the equipment you use inside out, starting with your helmet. Knowing how it works internally changes the quality of your daily check and lets you describe a symptom properly when something feels off.
Speak up plainly when something isn't right. Equipment that behaves oddly gets pulled, tagged and reported. Production pressure is always there, and the moment to push back against it is before you go in the water, not after.
And keep your own paperwork just as tidy as the equipment's: certificates, medical, courses. In an industry where the kit has to be certified, so do the people. If you're starting out, the catalogue of equipment and the guide to certifications are a good place to start for understanding what's out there and what's required.
Frequently asked questions
What should a diver check before every dive?
The visible condition of the helmet or mask, the fit and function of the supply valve, the emergency reserve and its shut-off, the harness, the umbilical along its full length, and communications. It's a functional check, not maintenance, and it doesn't replace workshop inspections.
How often is a diving helmet inspected?
According to the interval set by the manufacturer and the company's procedure, with periodic workshop inspections on top of the daily check. The specific intervals are in the model's manual, and that's what governs — not the team's usual habit.
What is traceability for a piece of lifting gear?
It's being able to identify every sling, shackle or hook and locate its certificate, its working load, and its inspection record. An item with no identification can't be certified and, in practice, shouldn't be used to lift load.
Who can carry out equipment maintenance?
User-level maintenance is done by the diving team according to the manual. Major maintenance and certification are handled by technicians and workshops authorised by the manufacturer or accredited under the applicable regulations, who issue the corresponding record.
Can I dive with equipment that works but whose inspection has expired?
No. In a regulated industry, the equipment's validity is established through documentation. Equipment with an overdue inspection is out of service for all practical and legal purposes, regardless of whether it appears to work fine.
Published 5 September 2026 · By Arthur More, professional saturation diver
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Photo: Commander, U.S. 7th Fleet · CC BY-SA via Openverse