Depends on the depth, generally we use regular compressed air down to about 170 fsw but if below 170 fsw we would use a gas mixture of heliox (helium and oxygen)
Argon and Helium are used as sheilding gases in welding.
Common gases used for welding include argon, helium, and carbon dioxide. These gases are often used as shielding gases to protect the weld area from atmospheric contamination and to help improve the quality of the weld. Oxygen and acetylene are also commonly used in oxy-fuel welding and cutting processes.
helium and argon
These inert gases are used in gas tungsten arc welding, and also in gas metal arc welding for the welding of non-ferrous metals. Semi-inert shielding gases, or activeshield gases, include carbon dioxide, oxygen, nitrogen, and hydrogen. These active gases are used with GMAW on ferrous metals.
Underwater welding uses a special flux around the welding rod which produces gasses which form a bubble around the end of the rod ,excluding the water. It is difficult and never as strong, lacking penetration. It is only used when absolutly necessary.
Underwater smokers are devices used in underwater welding and cutting operations to protect welders from harmful gases and provide a source of heat. They typically consist of a combustion chamber that burns fuel, producing smoke and heat to create a protective barrier around the work area. This helps to improve visibility and safety while performing underwater tasks in challenging conditions. Additionally, underwater smokers can aid in maintaining the temperature of the water to prevent freezing or other adverse effects on the welding process.
The two noble gases commonly used to protect during welding are argon and helium. They are used to create an inert atmosphere that shields the molten metal from reacting with oxygen and nitrogen in the air, preventing oxidation and ensuring a strong, clean weld.
Oxy-Gasoline is an effective fuel and is very good when traditional gas bottles are not available. Hydrogen is a good fuel when welding aluminium but is not used when welding steel because it damages the steel. Propane, butane and butane/propane mixes are also used.
The gases commonly used in welding are oxygen, acetylene, argon, and carbon dioxide. These gases play different roles in the welding process, such as providing heat, shielding the weld from atmospheric contamination, and facilitating the arc.
Depends on what you think of as normal welding. Gas welding use oxygen-acetylene. MIG/TIG use Argon. MAG, use an argon-something mix. Depending on what materials you are welding, there are some more options tha might be used.
In dry welding for underwater welding, a hyperbaric chamber is used to create a dry, pressurized environment for the welder to work in. The chamber is sealed to prevent water from entering and is pressurized to balance the external water pressure. The welder enters the chamber through an airlock system and performs welding tasks with the help of specialized equipment and gas supply systems.
Disadvantages of buying welding tools would be the new technology of spot welding which is flameless and and doesn't require the expensive inflatted gases.