Underwater blasting safety rules

A blaster must conduct all blasting operations, and no shot may be fired without the blaster’s approval. See 1926.912(a).

• This means the designated blaster on site has sole authority to determine when a shot is fired.
• Employers should make sure workers know who the blaster is and that only that person may authorize firing.

No — loading tubes and casings of dissimilar metals must not be used because galvanic action in water can create transient electric currents. See 1926.912(b).

• Use matching or compatible metals to prevent galvanic corrosion/electrical transients that could cause accidental initiation or other hazards.

Only water-resistant blasting caps and detonating cords shall be used for all marine blasting, and if a loading tube is necessary it must be a nonsparking metal loading tube. See 1926.912(c).

• Water-resistant components help ensure reliable initiation in a wet environment.
• Nonsparking metal loading tubes are required when a tube is needed to prevent ignition sources during loading.

No blast may be fired while any vessel under way is closer than 1,500 feet to the blasting area, and persons on vessels or craft moored or anchored within 1,500 feet must be notified before a blast is fired. See 1926.912(d).

• A vessel 'under way' must be at least 1,500 feet away when firing.
• If vessels are moored or anchored within 1,500 feet, they must receive advance notification so people aboard are warned.

No — blasts must not be fired while any swimming or diving operations are in progress in the vicinity of the blasting area; agreed signals and arrangements must be used to ensure no blast occurs while anyone is in the water. See 1926.912(e).

• Before blasting, confirm with dive/swim teams that all personnel are clear and that the agreed signal confirms the water is free of people.
• Document or record the agreed procedures so all parties understand the hold-and-fire arrangements.

Yes — blasting flags shall be displayed for underwater blasting operations. See 1926.912(f).

• Use clearly visible flags at required locations to warn nearby vessels and personnel.
• Flags are a visual control and should be used together with notifications and other warning systems required by the standard.

Explosives aboard vessels used in underwater blasting must be stored and handled according to the provisions outlined in the applicable handling and storing explosives requirements referenced by the standard. See 1926.912(g) and consult the broader explosives-handling rules such as 1926.911 for additional requirements.

• Follow the specific vessel storage and handling provisions in the explosives-related sections of Part 1926.
• Keep manifests, segregation, and safe stowage consistent with the applicable handling and storage rules referenced by 1926.912(g).

Each underwater charge must have a float device attached to an element of the charge in such a manner that the float will be released by the firing. Misfires must be handled in accordance with the requirements of 1926.911. See 1926.912(h).

• Attach one float per charge so each can be located/recovered after firing.
• If a charge fails to detonate (misfire), follow the misfire procedures in 1926.911 to protect personnel and property.

A nonsparking metal loading tube is required when a loading tube is necessary for the operation; the standard does not mandate a tube in every case. See 1926.912(c).

• Use a nonsparking metal tube whenever loading through a tube is needed to reduce ignition risks.
• Evaluate the loading method and use the tube only when necessary, ensuring it meets the nonsparking-metal requirement.

A vessel 'under way' must not be closer than 1,500 feet to the blasting area at the time a blast is fired; vessels that are moored or anchored within 1,500 feet may remain but must be notified before the blast is fired. See 1926.912(d).

• Under way = must be kept beyond 1,500 feet at firing time.
• Moored/anchored = can be within 1,500 feet but must receive advance notice so occupants are warned and can take protective actions.

The standard requires that signals and arrangements be agreed upon to ensure no blast is fired while any person is in the water, but it does not prescribe specific signals — employers and responsible parties must agree on and use reliable signals and procedures. See 1926.912(e).

• Typical arrangements include verbal confirmation, radio check-ins, visual clearance signals, or countdowns coordinated with dive teams.
• Whatever method is chosen, document it and confirm understanding with all involved parties before work begins.

Floats must be attached in a way that they are released by the firing so each charge can be located and recovered after detonation; this aids in confirming detonation and in recovering remnants. See 1926.912(h).

• Floats help divers or recovery crews find the exact charge locations and determine which charges detonated.
• Proper attachment ensures the float does not remain tethered to an unexploded charge, which could create hazards during recovery.

No — the standard requires water-resistant blasting caps and detonating cords for all marine blasting; non-water-resistant components are not permitted. See 1926.912(c).

• Using water-resistant components reduces the risk of misfires or unreliable performance due to moisture ingress.

No — blasting flags are required to be displayed under 1926.912(f), but notification to persons on vessels moored or anchored within 1,500 feet is separately required under 1926.912(d).

• Displaying flags provides visible warning to nearby craft and personnel.
• Employers must also proactively notify those aboard moored/anchored vessels within 1,500 feet before firing — flags do not substitute for direct notification.

Misfires must be handled in accordance with the requirements of 1926.911; consult that section for specific procedures on how to deal with misfires safely. See 1926.912(h).

• Do not attempt to fire another charge without following the misfire procedures in 1926.911.
• Ensure only trained personnel perform misfire recovery following the referenced section.

Yes — the storage and handling of explosives aboard vessels used in underwater blasting operations must follow the provisions outlined in the applicable handling and storing explosives requirements referenced by the standard, which align vessel practices with the broader explosives rules in Part 1926. See 1926.912(g) and consult 1926.911 for related handling and storage requirements.

• Vessel stowage must meet the same safety objectives (segregation, secure storage, and safe handling) required for any blasting operation.
• Ensure crew training, manifests, and storage arrangements comply with the referenced provisions.

The blaster conducting the operation is responsible for approving shots and must ensure blasting procedures are followed, but the employer and supervisory personnel are responsible for implementing and enforcing the broader requirements in 1926.912. See 1926.912(a) and the rest of 1926.912.

• The blaster controls firing decisions; the employer must provide compliant equipment, training, notifications, flags, storage, and procedures.
• Supervisors should verify distance restrictions, notifications, and that required water-resistant/dissimilar-metal prohibitions are observed.

Before firing, confirm that a qualified blaster will conduct and approve the shot, that only approved water-resistant components and compatible metals are used, that necessary nonsparking tubes are in place, that blasting flags are displayed, that vessels and any moored craft within 1,500 feet have been notified, and that no swimming/diving operations are in progress or that agreed signals are in place. See 1926.912(a)–(f).

• Verify float attachments for multiple charges and that misfire procedures per 1926.911 are understood.
• Document notifications and confirmations so the blaster has clear authority to fire.

While 1926.912 sets specific blasting safety requirements, employers must also assess workplace hazards and select appropriate PPE under general OSHA PPE rules; see OSHA's interpretation on PPE hazard assessment for guidance. See 1926.912 and the PPE hazard assessment interpretation at https://www.osha.gov/laws-regs/standardinterpretations/2024-03-28.

• OSHA’s PPE guidance explains that employers must assess hazards and provide suitable PPE when required (see the 2024-03-28 LOI).
• For underwater blasting, combine the 1926.912 requirements (water-resistant components, safe handling, notifications) with a job-specific PPE hazard assessment to determine protective clothing, hearing protection, floatation, and rescue equipment.