OSHA 29 CFR 1910 Subpart T: The Commercial Diving Rules in Plain English

By Ray Whitfield, ADCI-certified commercial dive supervisor. Reviewed by Dana Whitcombe, technical reviewer.

Commercial Diving Contractors Alabama | Commercial Diving Contractors Alaska I was forty feet down under a bridge pier in the Ohio River, silt so thick I couldn't see my own knife, when the tender tapped on my helmet and said the OSHA inspector wanted to talk to me. I surfaced, pulled the mask off, and the first thing he asked was, 'Where's your dive plan?' I handed it to him. He read it, nodded, and said, 'This is good.' That's the thing about 29 CFR 1910 Subpart T — it's not a binder you file away. It's the difference between coming home or not. I'm Ray. ADCI-certified dive supervisor, 28 years on inland and industrial jobs — dams, bridges, water tanks, power plant intakes. I've made thousands of dives, and I can tell you this: OSHA's commercial diving standards aren't bureaucracy for its own sake. They're boiled-down lessons from people who didn't come home. So here's what Subpart T actually says, in plain English. If you're running a dive operation anywhere in general industry, this is the floor. It's not the ceiling, and it's not the only rule. But it's the one that can shut you down.

What Subpart T Actually Covers

Subpart T is the general industry standard for commercial diving. If you're doing work on a bridge pier that's not part of construction, you're under Subpart T. If you're doing construction work underwater — say, building a cofferdam for a highway bridge — you're under 29 CFR 1926 Subpart Y, not Subpart T. Both are nearly identical, but the nuance matters. And don't get confused: 1926 Subpart T is demolition. Different world. The standard applies to all commercial diving operations, including in-land, inland, whatever you want to call it — the word is 'inland,' not 'in-land.' That includes salvage, inspection, repair, and installation. It covers SCUBA, surface-supplied air, mixed gas, and saturation. If you're getting paid to go underwater, Subpart T is probably in the picture. There are exemptions. Scientific diving — under defined conditions — can get a pass, but not when it's part of a construction or industrial job. And if you're a recreational instructor taking a tourist to see a wreck, Subpart T doesn't apply. But the line gets fuzzy. My rule: if the dive supports a commercial operation, treat it like commercial diving.

The Dive Team: Nobody Dives Alone

Subpart T is clear about something that should be common sense: you need a dive team. That means a designated supervisor, a diver, a tender, and a standby diver. The standby diver is suited up, ready to go in the water, and for any dive that isn't an actual rescue, they stay on the surface. One guy looking after the air hose and one guy ready to go in. You can't be your own tender, and the supervisor can't also be the standby diver if they're the only one there. The rulebook doesn't say 'one man shall tend the line while another man may hold the spare mask,' but that's the gist. The supervisor has to be experienced and, frankly, able to make the call to abort. I've cut dives short because the current picked up, and nobody argued. Under Subpart T, the supervisor has to have a valid certificate of medical fitness, too. And every diver has to be trained in first aid and CPR. There's also a requirement for the dive team to be familiar with the specific hazards of the site. That means you sit down and talk through the plan before anyone gets wet. One thing I'll digress on: I've seen too many small outfits run a two-man team — a diver and a 'guy on the line.' That's not a dive team. That's a disaster waiting to happen. OSHA will cite you, and the current doesn't care. Washington, D.C., cares. The Ohio River cares. The current cares.

Equipment: The Rulebook's Practical Side

Subpart T lays out equipment requirements that read like a checklist, but they're a pile of gear you need to keep in good shape. Breathing air has to meet purity standards — CGA Grade E, give or take. That means a filtration system on your compressor, and you test the air regularly. I carry a little portable air sampler and send the lab reports off to the company file. You need a depth gauge, a timer, and a dive log for every diver. For SCUBA, you need a submersible pressure gauge. For surface-supplied air, you need a one-way check valve near the diver and a pneumo gauge. The compressor has to have a volume tank and a check valve. And every diver gets a helmet or mask, a weight belt, a harness, a knife — and a dive suit that actually fits. Here's a thing a lot of newcomers miss: the standard requires communication. A diver tends to go where the work is, and if you can't talk to him, you can't bring him up. I've worked off a simple 'tug on the line' system in zero-viz, but Subpart T wants something better — a two-way voice system for surface-supplied air dives. And that communication system has to work, not just be in the truck.

Procedures: Plan the Dive, Dive the Plan

Subpart T doesn't tell you how to dive a specific job. It tells you what has to be in writing before you descend. Dive plan: max depth, bottom time, decompression schedule, breathing gas mix, and the emergency procedures. You need decompression tables or a dive computer, and someone on the team who knows how to use them. I've had a dive computer fail on a 130-foot job; without a backup plan, that's a problem. The standard also requires an emergency action plan that includes an oxygen resuscitator and a first aid kit. It needs a list of the nearest recompression chamber, and a way to get the diver there. On inland jobs, that might be a two-hour drive. I've made that drive once, and never want to again. There's also a recordkeeping thing: you have to log every dive. Time in, time out, depth, gas, any problems. That log is legal proof you operated according to the plan. If an inspector asks, you hand it over. It also protects you in a lawsuit.

Common Misconceptions and Staying Compliant

One of the biggest misconceptions is that a recreational certification from PADI, NAUI, or SSI makes you a commercial diver. It doesn't. Subpart T doesn't require a specific school, but it does require training and experience commensurate with the hazards. A weekend certification isn't that. ADCI publishes consensus standards and training programs, but ADCI is not a regulator. It's an industry association. OSHA is the cop. You can have an ADCI card and still get cited if you skip the dive plan. Another one: 'It's just a quick inspection, we don't need all that.' That's exactly when things go wrong. I've done 200-foot penetrations on dam intakes where the delta P math told us to stay away from the grate. That's where the real rules live — not in Subpart T, but in your own pre-dive hazard analysis. Subpart T is the minimum. Add to it what the job demands. To stay compliant, run your operation like the inspector is watching. Because sometimes they are. Keep your dive logs, test your air, keep your equipment maintenance records, and never let a diver go down without a standby diver. That's not OSHA's rule; that's survival.

Frequently Asked Questions

Does OSHA 29 CFR 1910 Subpart T apply to all commercial diving? Subpart T covers general industry commercial diving. Construction diving falls under 29 CFR 1926 Subpart Y. Scientific diving may be exempt under defined conditions. If you're paid to dive commercially, assume it applies. What is the difference between Subpart T and Subpart Y? Subpart T is general industry; Subpart Y is construction. The requirements are nearly identical, but the trigger is the nature of the work. Bridge construction vs. Bridge inspection is a classic example. Do I need a standby diver for every dive? Subpart T generally requires a standby diver at the dive location whenever a diver is in the water, with limited exceptions for specific scuba operations. The standby diver must be ready to enter the water immediately. What is the main thing OSHA looks for during an inspection? OSHA inspectors typically look for a dive plan, a qualified dive team, and records of dive logs and equipment maintenance. Without those, a dive gets shut down.