What Is Underwater Welding?

Underwater welding makes the welding process more complicated due to the presence of water, and there will be a variety of problems not encountered in land welding. At present, there are many types of underwater welding methods being applied and studied in various countries around the world. The mature is arc welding. 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 appeared. However, from the perspective of the ocean development of various countries, the research of underwater welding is far from meeting the needs of the development of the situation. Therefore, strengthening research in this area will be a very meaningful work for both now and in the future.

Underwater welding

Underwater welding and cutting is an indispensable important process in the installation and maintenance of underwater engineering structures. They are often used at sea

There are three types of underwater welding: dry, wet and local dry.

Dry welding

This is a method that uses a large gas chamber to cover the weldment and the welder applies welding in the gas chamber. Since it is welded in a dry gas phase, its safety is better. When the depth exceeds the submerged range of air, Mars is easily generated due to the increase of local oxygen pressure in the air environment. Therefore, an inert or semi-inert gas should be used in the gas chamber. When dry welding, welders should wear special fire-resistant, high-temperature resistant

The underwater environment makes the underwater welding process much more complicated than the onshore welding process. In addition to welding technology, it also involves many factors such as diving operation technology. The characteristics of underwater welding are:

1. Poor visibility. Water absorbs, reflects, and refracts light much more strongly than air, so light weakens rapidly when it travels through water. Also when welding

1. It is recommended that all the cable parts below the waterline and underwater cable parts of the dedicated welding wire above 50 square meters must be completely insulated.

2. Before starting operation, check all cables and connected machines for damaged insulation. Damaged ones must be replaced and defective ones repaired.

3. The capacity of the cable must be able to meet the requirements of the maximum current of the workpiece. The capacity of the connected machine should be at least equal to the capacity of the cable.

4. All connected machines must be fastened and completely insulated. Therefore, the underwater machine should be held tightly with a rubber bag to prevent current loss.

5. Make sure there are no connectors for cables within ten feet of the welding tongs.

6. Route the ground cable to the workpiece in such a way that the body of the diver will never be in

1. Connect the negative lead of the safety switch to the welding tongs, and keep the safety switch in a place accessible to the caretaker.

2.

The risk factor of underwater welding and cutting is that the arc or gas flame is used underwater, which is more dangerous than welding in the atmosphere or general diving operations.

Common accidents in underwater welding and cutting operations are: electric shock, explosion, burns, burns, drowning, scoring,

Underwater welding and cutting safety measures

Ready to work

An important feature of the safety work of underwater welding and cutting is that there are a large number of preparations, which generally include the following aspects:

1. Investigate environmental conditions such as weather, water depth, water temperature, and velocity in the operation area. When the wind on the water surface is less than 6 and the flow velocity of the operating point is less than 0.1 ^} 0. 3m / s, the operation can be performed.

2. Before the underwater welding and cutting, the nature and structural characteristics of the welded and cut pieces should be identified, and whether there are flammable, explosive and toxic substances in the operation object. Properly fix objects that may fall or collapse, especially when cutting underwater, to prevent injuries or damage to the air supply pipe and cables.

3. Before diving, check and test the insulation, watertightness, and technological performance of welding and cutting equipment and tools, diving equipment, gas supply pipes and cables, and communication tools on the water. The oxygen hose must be cleaned with steam or hot water at 1.5 times the working pressure, and no grease can be adhered to the inside and outside of the hose. The air pipe and cable should be bundled firmly every 0.5m to avoid twisting each other. After diving underwater, you should arrange the air supply pipes, cables and signal ropes in a timely manner to keep them in a safe position to avoid damage.

4. Above the operation point, within the area with a radius equal to the water depth, no other operations may be performed at the same time. As unburned or toxic gas escapes and floats to the surface during underwater operations, water personnel should have fire prevention preparations, and the air supply pump should be placed upwind to prevent fire or underwater personnel inhaling

1. As each welding method (wet method, local dry method, dry method) has its own advantages and adaptable occasions, the coexistence of multiple underwater welding methods will persist for a long time.

2.The quality of wet underwater welding is mainly affected by

1. Welding and cutting torches (guns, handles) should be inspected for insulation, water tightness and process performance before use. Tests should be performed on the water surface first. Oxygen hoses should be cleaned with steam or water at 1.5 times the working pressure before use. There must be no grease inside or outside the hoses. Power cables must be inspected for insulation. Heat-cut air-supplying hoses and cables should be bundled securely at 0.5m intervals.

2. The submersible welding and cutting machine should be equipped with wireless communication tools in order to get in touch with the support personnel on the water at any time. Underwater welding and cutting operations are not allowed without any communication. After the submerged welding and cutting workers enter the water, other operations are prohibited in the area where the radius of the water surface at the operating point is equivalent to the depth of the water.

3. Before the underwater welding and cutting, the surrounding environment of the operation area should be identified, and the water depth, hydrology, meteorology and the structure of the object being welded and cut should be familiar. Submersible welders should be given a suitable working position, and welding operations should not be carried out in a suspended state. General submersible welding and cutting workers should stay on the component or the operating platform set in advance.

4. Before the underwater welding and cutting operation is started, the gas supply hoses, cables, equipment, tools and signal ropes should be carefully checked and arranged. Under no circumstances should these equipment and the welding and cutting workers themselves be splashed and flowed by slag On the route. Obstructions around the operating point should be removed, put themselves in a favorable and safe position, and then contact the surface personnel and obtain consent before welding.

5. Underwater operating points are subject to water flow speeds in the range of 0.1 to 0.3 m / s, and when the wind on the surface exceeds 6 levels, underwater operations are prohibited.