Underwater Welding Cutting Kamsar
Welding and cutting are the core tools of underwater ship repair. Done well, they allow a Diver to remove damaged steel, fit patches and secure structures while the ship stays afloat. Done badly, they are dangerous and give poor results. This page describes how underwater welding and cutting in Kamsar is carried out, and the controls that make it safe and acceptable to class.
Underwater Welding
The Diver uses a shielded metal arc process with waterproof-coated electrodes, powered by a direct current welding set on the surface. Cables, electrode holders and switches are built for underwater use. Because the arc burns inside a gas bubble surrounded by water, the weld cools fast. Welding procedures set the electrode type, current range and run sequence to give a sound weld within these limits.
Underwater Cutting
- Oxy-arc cutting: an arc heats the steel and a stream of oxygen blows out the molten metal. It is the standard method for cutting steel plate underwater.
- Exothermic cutting: a burning rod gives very high temperature and can cut steel and other metals, useful for thick sections.
- Mechanical cutting: hydraulic shears, saws and diamond wire are used where heat is not acceptable, such as near fuel tanks.
- Water-jet cutting: used for specialist jobs where hot work is unsuitable.
Safety Controls
Underwater hot work needs specific safety rules. The welding set has a knife switch controlled by the supervisor, so the current can be cut at once if needed. The Diver wears insulated equipment, and the work is planned so that the diver is not between the electrode and the earth return. Cutting generates hydrogen and oxygen gas, which can collect in enclosed spaces and explode, so we vent or avoid trapped pockets and never cut near unsafe tanks.
Controlling Hot Work on the Ship
Before cutting or welding on a hull, the ship's crew must confirm that spaces behind the work area are gas-free and safe. The chief officer or chief engineer signs a hot work permit, and the master agrees the plan. If tanks behind the plate contain oil, fuel or flammable vapour, we do not cut or weld until the area is certified safe or a cold method is chosen.
Welder-Divers and Procedures
Underwater welding is performed by Divers trained and tested for the method. For class work, welders may need to pass procedure and welder qualification tests, as set by the society. We keep records of the procedure, electrode batch and run sequence, and attach them to the repair report, with photographs and video of the welded area.
Inspection of Welds
After welding, welds are cleaned and inspected visually, by CCTV and close-up photographs. Where required, we carry out magnetic particle or ultrasonic inspection. Any weld that does not meet the agreed standard is ground out and re-welded. If a repair is temporary, the limits are stated clearly in the report.
Request Welding or Cutting
Send details of the work, and we will propose a procedure and safety plan.
Training and Qualification of Welder-Divers
Underwater welding demands two skills: diving and welding. Welder-Divers train in both, and tests for welding procedures are usually required for class work. We select personnel with proven experience, check their certificates and record the procedure used. Where the class asks for a welder qualification test, we arrange it before the repair so the welds are accepted. This preparation protects the owner from rejected work.
Weather and Tide Limits
Welding and cutting stop in poor weather or strong current, because the Diver cannot work safely and the arc becomes unstable.
Frequently Asked Questions (FAQ)
Q1. What cutting method is used most underwater?
Oxy-arc cutting, which can cut steel plate efficiently in shallow water.
Q2. Why is a safety switch used in underwater welding?
It lets the supervisor cut power instantly, protecting the Diver from electric shock.
Q3. Can cutting be done near fuel tanks?
No hot cutting. A cold method or a certified gas-free condition is required.
Q4. What current is used for wet welding?
Typically in the range of 200 to 400 amps DC, depending on electrode and plate.
Q5. Are wet welds as strong as dry welds?
They are typically harder and more brittle, which is why class often accepts them only for temporary or non-critical repairs.