In this post, we will discuss how does underwater welding work? and Its Types of Underwater welding. You can also download the PDF file of this article at the end of it.
Underwater Welding Process
In 1932 Russian metallurgist (Konstantin Khrenov) invented underwater welding. Underwater welding is also called hyperbaric welding. It is the process of welding at high pressure in underwater.
When it is used in a dry environment called “hyperbaric welding“. And in the wet environment called “underwater welding“.
Dry welding is used in the preference of welding under wet water when the high-quality weld is required. Due to the increased control in the situations which can be done through the use of before and after weld heat treatment.
Thus, when a very high-quality weld is required, dry hyperbaric welding is used. Research is underway to use dry hyperbaric welding at depth of 1,000 meters (3,300 feet). In general, assuring the integrity of underwater welds can be complex. (But it is possible using various non-destructive testing applications). Mainly for wet underwater welds.
There are two methods of underwater welding 1. Wet welding, and 2. Dry welding.
Applications of hyperbaric welding.
- It is usually used for the repair of ships, offshore oil platforms, and pipelines.
Types of Underwater Welding
There are mainly two types of weldings performed underwater:
- Wet Welding
- Dry Welding
#1 Wet Welding
This method is done underwater. This involves the use of designed welding rods and involves the same process used in standard welding.
Wet underwater welding exposes the diver and electrode to the water and surrounding elements. Divers use around 300–400 amps of D.C power to charge their electrodes, and they weld using varied forms of arc welding.
Due to hydrogen cracking, the process is usually limited to low-carbon equivalent steals, especially in greater depth. Wet welding is done with the same equipment used for dry welding, but the electrode holders are designed to cool the water and are heavier insulating.
Advantages of wet welding:
- The wet welding process is faster and cheaper.
- There is no habitat.
- high tensile strength.
- Ease of access to weld spots.
#3 Dry Welding or Hyperbaric Welding
Hyperbaric welding is the process by which a chamber is sealed around the structure that is to be welded. It is filled with a gas (usually a mixture of helium and oxygen, or argon), which then forces water outside the hyperbaric region. This allows for a dry environment in which to perform the weld.
Advantages to dry welding:
- It has a high quality of welding.
- It has welder or diver safety.
- Dry welding has non-destructive welding.
- It has surface monitoring.
Underwater Welding Equipment
To weld properly underwater, a commercial diver uses five main tools:
- Diving helmet
- Diving suit
- Power supply
#1 Diving Helmet
The figure shows the diving helmet for the underwater welding process. It is essential to wear a safe diving helmet for their work. During the welding process helmet, protect our eyes and face.
Also, the diving helmet allows breathing for the welder-diver in underwater, so that’s it used in underwater purpose. A welding screen that attaches to the front of their mask for eye protection. Some of these welding screens flip up or down like a welding hoods, and they all come in different colours.
#2 Underwater Welding Diving Accessories
welder-divers will use these diving accessories:
- Diving knife
- Umbilical cord
- Gas panel and compressor
- Bailout gas
- Knife switch
#1 Diving knife
It is a tool for every situation. Whether they need to cut into project material, wedge opens a door or free themselves from a Critical condition a diving knife works.
#2 Umbilical cord
This is gas is pumped from the diver too and from the surface.
To keep the diver floating in one place while doing his work.
#4 Gas Panel and Compressor:
A qualified team controls the gas gauge and keeps the steady supply of air coming below in the diver. Divers also observe these directly. Many uses a low-pressure gas because of its low maintenance is almost unlimited air supply.
#5 Bailout Gas
It is used for emergency situations, in the case of poor SSA equipment, this gas is usually done by the diver as a secondary gas supply. It comes in the form of a small SCUBA tank.
#6 Knife Switch
Not the same as a diving knife. It is used when using electrical appliances underwater like wet welding. Built in the form of a simple liver, it regulates the flow of electricity from the upper side to power your device.
#3 Diving Suit
For the diving purpose divers must use a dry suit because it provides better protection against climate control than a wetsuit.
Depending on the environment in which you diving, dry suits either are neoprene, rubber or shell.
However, as an extra external layer of protection, some underwater welders wear coveralls at the top of their suit.
If a molten metal directly hits its suit, then it can burn through it. Coverall prevents it from occurring.
To protection of hands, welder-divers wear thick, rubber linemen’s gloves over several pairs of latex. To prevent the water from being in gloves, they can snap a rubber band around the wrist section.
The electrodes are the most important tool of underwater welding it provides materials for the weld. underwater electrodes should be extremely water-resistant coating and high yield strength.
Water-resistant coating: The longer it can hold up in a hostile marine environment, the better.
High yield strength: Better quality material in the electrode provides a high-density weld which will last for a long time.
Stingers hold the electrodes, and they are made of lightweight plastic materials to reduce the possibility of twinge and fatigue. The stinger has the following characteristics:
- It should be insulated.
- It should have Ergonomic and lightweight.
- Angled Correctly.
#6 Power Supply
For every welding process, the power supply must be required. In underwater welding, DC power source is usually used.
The power source for under-water manual metal arc (MMA, SMA / SMW) welding should be direct current welding generator type, which is able to produce at least 300 A on 65V open circuit (OC).
Equipment welding circuit should include a DC circuit breaker (twin pole single action, 400 A minimum).
So now, we hope that we have clear all your doubts about Underwater Welding Process. If you have still any doubts about the “Types of Underwater Welding” you can contact us or ask in the comments. If you like our article, then please share it with your friends.
Subscribe to our newsletter to get notified when we upload new posts.
Download PDF of this article:
You may be interested in reading more articles on welding:
- What are the Types of Welding Joints (Explained in Detail)
- Common Types of Welding Defects [Causes & Remedies]
- What is the Difference Between Tig and Mig Welding?