The underwater welding process becomes more complicated because of the existence of water, and there will be various problems that are not encountered in land welding. At present, there are many underwater welding methods being applied and studied all over the world, and arc welding is a mature one. With the development of underwater welding technology, in addition to the commonly used wet underwater welding, local dry underwater welding and dry underwater welding, some new underwater welding methods have emerged. However, from the perspective of marine development in various countries, the research on underwater welding is far from meeting the needs of the development of the situation. Therefore, whether now or in the future, it will be a very meaningful work to strengthen the research in this field.

Underwater welding and cutting are indispensable and important technical means in the installation and maintenance of underwater engineering structures. They are often used in marine salvage, marine energy, marine mining and other marine projects, as well as the construction of large underwater facilities.

Welding power supply must be DC, and alternating current is prohibited. Because at the same voltage, the alternating current passing through the diver's body is greater than the direct current. Compared with DC, the arc stability of alternating current is poor, which is easy to cause large splash and increase the danger of burning diving equipment.

2, all equipment and tools should have good insulation and waterproof performance, insulation resistance shall not be less than1m.. In order to prevent the corrosion of seawater and atmospheric salt fog, it is necessary to coat an insulating sheath with reliable water tightness and good grounding.

Dry welding

This is a method that the weldment is covered with an atmospheric chamber and the welder welds in the air chamber. Because it is welded in dry gas phase, the safety is better. When the depth exceeds the diving range of air, it is easy to produce Mars due to the increased simulated pressure of local oxygen in the air environment. Therefore, inert or semi-inert gas should be used in the gas chamber. When dry welding, welders should wear special fire-proof and high-temperature protective clothing.

Compared with wet welding and local dry welding, dry welding has the best safety, but it has great limitations and is not widely used.

Local dry welding

Local dry welding is an underwater welding method. Welders weld in water and manually drain the water around the welding area. Its safety measures are similar to wet welding. Because the local dry method is still under study, it is not widely used.

Wet welding

Wet welding is an underwater welding method. Welders weld directly under water instead of manually draining the water around the welding area.