Commercial Diving Standards: OSHA Subpart T, ADCI and Insurance
A bridge engineer, water superintendent, or port facility manager does not need to be a commercial diving expert. You need to know what standards the contractor you hire must meet, and which insurance actually covers the work. This page lays out the governing rules: OSHA 29 CFR 1910 Subpart T, ADCI (Association of Diving Contractors International) consensus standards, and the maritime insurance framework that determines whether a dive contractor can absorb a serious incident. It also covers work-specific standards like NBIS for bridges, AWWA M42 and C652 for tanks, and USCG UWILD requirements. The point is practical: safety compliance and procurement are the same issue. A low bid may look fine on paper and still leave the owner exposed if the contractor misclassifies divers, skips supervision, or carries the wrong coverage. The difference between recreational scuba and commercial diving is not depth; it is the legal and operational structure around the work. Here is what to check before you sign.
OSHA Subpart T sets the legal floor
The federal rule is 29 CFR 1910 Subpart T, issued by OSHA. It applies to any commercial diving operation in U.S. coastal and inland waters, including work on bridges, tanks, pipelines, and vessel hulls. Subpart T requires a dive team with defined roles: a supervisor, the diver in the water, a standby diver, a tender, and—when the dive profile requires it—a person at the control panel for a bell or a deck decompression chamber. The rule specifies minimum equipment, air quality, depth limits, emergency procedures, and medical qualifications. It also mandates a written safe practices manual and a system for reporting accidents. State-plan states may have their own rules, but they must be at least as strict. For a plain-language breakdown of the rule, see our article on OSHA Subpart T in plain English. The short version is that the rule is not a preference. If your contractor cannot cite the paragraph numbers, you have not hired a commercial diving operation.
ADCI consensus standards define good practice
OSHA writes the rules. ADCI—the Association of Diving Contractors International—publishes consensus standards that describe how responsible contractors run a dive. These standards cover dive supervisor certification, diver training, equipment inventories, decompression procedures, and recordkeeping. They go beyond Subpart T in areas where the federal rule is silent. For example, ADCI requires a designated dive supervisor for every operation and specifies the training that supervisor must have. In litigation, ADCI standards are often introduced as evidence of the standard of care. An insurer will look at whether the contractor follows ADCI before writing a maritime liability policy. A contractor that says 'we follow OSHA' but has no ADCI accreditation may be technically compliant, but you have no independent verification. When you ask for a bid, ask for the ADCI certificate. The contractor should be able to name the supervisor who will be on site. This is not paperwork. It is how the industry separates practitioners from weekend charter operations.
Insurance: Jones Act, USL&H, and the real cost of a low bid
Dive contractors operate under maritime law, not just workers' compensation. If the work takes place on or over navigable waters, the Jones Act and the Longshore and Harbor Workers' Compensation Act (USL&H) can apply. These statutes create liability for vessel owners and employers. A diver is not necessarily an independent contractor even if the paperwork says so; courts look at control. If a diver is injured and the contractor has no USL&H coverage, the property owner or the general contractor can be named in a Jones Act claim. Maritime employers' liability insurance covers some of these risks, but only if the policy is written for diving operations. Many standard commercial general liability policies exclude diving, and a state workers' comp policy does not cover maritime injury. The result is that a low bid may come from a contractor who simply does not carry diving insurance. Underwriters who know diving will not write a policy for a shop that disregards OSHA or ADCI. Read our article about why the cheapest bid may be uninsurable.
What standards apply to the structure, not the dive
Subpart T covers how the diving is done. The structure itself has its own inspection or repair rules. For underwater bridge inspections, 23 CFR 650.311 and the National Bridge Inspection Standards (NBIS) require that a qualified team leader lead the inspection. That team leader must have specific FHWA-NHI training and be a certified commercial diver, not simply a recreational one. For potable water tanks, AWWA M42 describes inspection intervals and AWWA C652 covers disinfection after a repair. Any material that touches potable water must meet NSF/ANSI 61. For vessel hulls, 46 CFR 71.50-3 sets the conditions for an in-water hull examination (UWILD). For underwater welding, AWS D3.6M is the code that governs weld quality. If the work is for the U.S. Army Corps of Engineers, EM 385-1-1 adds safety requirements on top of Subpart T. You can put all of this in a single sentence, but you cannot hire a contractor who does not know it. Ask the contractor to state which standard governs your asset type. If they hesitate, keep looking. Use our checklist when you shortlist a contractor.
Why scuba training is not enough and why delta P is different
Recreational scuba certification is a hobby credential. It does not train a person for commercial diving, and it does not meet OSHA or ADCI requirements. A PADI Open Water card does not cover rigging, underwater cutting, thermal stress, or the legal duties of a commercial diver. A dive master with a thousand dives is not a commercial supervisor. The work is physically harder and logistically more complex. One hazard separates this trade from any other: differential pressure, known as delta P. It occurs near intakes, gates, and valves when water moves through an opening. The pressure differential can pin a diver against the structure. The force is measured in tons, and no diver can pull free. Positive isolation—locking out valves, installing blanks, or dewatering the line—is the only safe method. It cannot be taken for granted. Every dive plan for a water or power facility should address delta P explicitly. If a contractor treats it as routine, that is a warning sign. Read our explanation of why commercial diving is not scuba and the article on differential pressure, the hazard that kills divers.
Standards and insurance questions
Does OSHA Subpart T apply to a one-day inspection of an intake structure?
Yes. Subpart T applies to all commercial diving operations in U.S. waters or in state waters where a state plan is in effect. The size of the job does not matter. A single inspection still requires a dive supervisor, standby diver, tender, and written procedures.
Our contractor says they have 'OSHA-certified divers.' Is that a thing?
No. OSHA does not certify divers. OSHA writes the regulations; it does not issue certifications. Credentials come from a training institution recognized by ADCI or from ADCI's own supervisor certification. Anyone who says 'OSHA-certified' is not familiar with the industry.
What insurance should a dive contractor carry for work on my bridge?
They need USL&H coverage for the divers, maritime employers' liability, and a general liability policy that explicitly covers diving operations. If they have a vessel, it should be covered under a hull and P&I policy. Ask for a certificate of insurance naming your agency as additional insured. Have your risk manager review it.
Who is the 'qualified team leader' for an NBIS underwater bridge inspection?
The team leader must meet the FHWA-NHI training and experience requirements in 23 CFR 650.309 and be a commercial diver qualified under Subpart T. They are responsible for the inspection report, not just the dive. Ask for proof of both qualifications before awarding the contract.