How To Prevent Electric Shock For Underwater Welding Square Tube?

When we weld the rectangular tube underwater, we should pay attention to prevent electric shock. In this regard, the following eight measures can be taken:

(1) Underwater welding equipment and power supply should have good insulation and waterproof performance, and their insulation resistance value should not be less than 1MΩ and should be resistant to salt spray corrosion, atmospheric corrosion, and seawater corrosion. 

(2) When underwater wet welding and cutting square tubes, an automatic switch box dedicated to welding should be installed in the circuit. For underwater dry or partial dry welding, an accident alarm system and a power-off system shall be installed in the circuit control system.

(3) The electrodes should be thoroughly insulated and waterproof to ensure that electrical contact occurs only where the arc is formed.

(4) Diving welders must wear special protective clothing and special gloves when operating square pipes.

(5) As soon as the underwater arc is formed, the surrounding water evaporates to produce cavities or bubbles. The voltage required to strike an arc underwater is higher than on land due to the cooling and pressure of the water. From the perspective of operational safety, the underwater welding power supply must use direct current, and the use of alternating current is prohibited. Its no-load voltage is generally between 50-80V.

(6) The control electrical appliances that are in direct contact with the diving welder must use an isolation transformer and have overload protection. The electric welding machine for square tube welding must be grounded, and the grounding wire must be polished to prevent corrosion.

(7) In welding or cutting, it is often necessary to replace the welding rod. When changing the welding rod underwater, you must first send out a switch signal to confirm that the circuit has been cut off before removing the welding rod head and then replacing the welding rod. Otherwise, it is easy to cause electric shock accidents and cause danger.

(8) When the rectangular pipe is welded underwater, the diving welder must not turn his back to the grounding point, that is, place himself between the working point and the grounding point. Otherwise, it is not only prone to electric shock accidents but also prone to electrolytic corrosion of the metal parts of diving equipment. In addition, be careful not to put your hands on the workpiece to be welded and cut, and at the same time touch the welding rod or welding handle to the helmet and receive an electric shock.