Underwater dry welding is basically the same as regular welding, just in more extreme conditions. The process of welding is used to link metals or thermoplastics by using coalescence. It takes place when a filler metal and the work pieces of metal are melted. The filler substance is used to create an outlined band of melted material known as the weld puddle once it cools a strong joint is formed.
Underwater welding (aka Hyperbaric welding) is a process of assembling or repairing items under water. This technology is extremely useful as it serves to effect repairs to items that have been damaged during wars, hurricanes or mid-sea collisions. There are other processes which can be used such as bolted flanges and clamped repairs but they do not provide the strength that welding does and it is used mainly for specialized industries such as the oil and shipping industries and the military.
When people think of water and electricity they know they are not compatible and the final outcome of such a combination can mean serious injury or even death. Carrying out welding underwater carries a number of risks, but by following the safety procedures outline for this practice the risks can be minimized. However, it is this danger that allows welders to earn such high underwater welding pay.
If you plan on doing underwater welding for a repair or building assignment keep in mind that there are two types of underwater wet welding and underwater dry welding. For the dry welding process, the area that needs welding is isolated from water. Currently there are several methods that can be used to carry out this process. A pressurized chamber can be wrapped around the weld area to remove water and keep the diver/welder dry.
Underwater dry welding requires much time and resources for this reason wet welding is often used as a fast, temporary fix. Wet welding is done in the actual water there is no chamber or device to protect the welder from the water. The weld may not be as strong as a dry weld due to the possible environmental contaminants.
Wet welding is susceptible to cold and hot spots as well as pockets of gas that may be trapped in the weld. These defects reduce the structural integrity of the weld. Experts advise that wet welding should only be used as a temporary solution until the necessary resources are in place to carry out a underwater dry welding.