How Does Underwater Welding Work? What’s the Science Behind?
A very interesting way of welding is underwater welding. This process is obviously very difficult and comes with its own complications and rules since it is not handled the same way the regular welding done on land is. The process is even more critical than orbital welding.
There will come a time when you will need to weld certain metallic things while being submerged underwater because of situations that do not let you bring the metal parts or bodies up to the surface to perform the general welding methods.
So, knowing how does underwater welding work and the science behind it all is helpful for those dire situations.
The Science Behind How Underwater Welding Works
When you are involved in ship construction, you specifically need to know about underwater or hyperbaric welding. The types or methods of underwater welding are given below with their step by step processes:
Method 1: Wet Welding
In this section, we’ll detail the wet welding process.
Step 1: Examine Areas to Be Welded
You first need to investigate or examine the surfaces or areas that you will be welding. This includes cleaning up the metallic surfaces and finding out what kind of metal they are. It will affect the amount of heat you will require to weld the metal parts together.
Step 2: Charge Up the Electrodes
In underwater welding, you need to use an electrode that has plasma, an anode, and a cathode. The anode needs to be charged positively while the cathode needs to be charged negatively.
This is done because the anode and cathode are of opposite charges, and this helps the electrons travel quickly between the cathode and anode. The electrons will move down from the cathode to the anode and the positive ions move up from the anode to the cathode.
While these particles are moving back and forth between these two points, a large amount of energy is forming. This makes the arc from the welding tool heat up to 5000 degrees Celsius and above. That arc is also protected by a gaseous bubble around it, which is waterproof.
Because of this bubble, the welding tool can weld the metal parts together while underwater.
Step 3: Make a Plan or Schedule
Since you will be diving into the water, you need to prepare some diving gear and extension cords for your welding tools and your other body gear. You should pinpoint exactly where the spot of the welding site is and discuss the time you might need with your coworkers.
When you have ascertained the weld site or spot, you should also check the surroundings to ensure you will be safe in that area when you are busy welding. Make sure to check for any sharp objects around or if there might be any dangerous marine animals swimming around.
To be on the safe side, you can also arrange some breaks in between welding to avoid accidents. And in the meantime of the breaks, you should check your gear every time before you dive back in again.
Step 4: Begin the Wet Welding
Once you have dived in with all your welding gear and have safely positioned yourself, you can signal your coworkers to turn on the power switch for the welding tool so that you can begin welding the joints.
Place your electrodes on the metal surface where the joining will take place. When the power is first generated, you will get around 300 or more amperes of electricity traveling through as direct current (DC).
Hold the metal parts or surfaces together and begin welding. If the parts are large and heavy, you must take in another diver or more to help you hold the parts together while you handle the welding.
Step 5: Shut Down
When you are done welding, signal your coworkers who are on the surface so that they can turn the power off. Given that the welding has taken place underwater, the water will cool down the metal very fast, which will make it harden quickly.
You only need to wait for a while before checking to see if the welded joints are strongly in place. Then you can swim back up to the surface.
Method 2: Dry Welding
Let’s go through the dry welding process.
Step 1: Understanding Dry Welding
Dry hyperbaric welding is also sometimes known as habitat welding. This is a bit different from the wet hyperbaric welding process. That is because there is a hyperbaric chamber is involved in this process.
You need to mark or make a seal around the metal structure or area you will be welding. Some hoses will be connected, and these hoses will push out water and fill the empty space with different light gases like oxygen, helium, etc.
The hyperbaric chamber is then pressurized to a certain amount of depth so that it doesn’t cause decompression sickness.
Step 2: Examining Areas in Welding Site
Just like in the wet hyperbaric welding process, here you also need to investigate the areas that you will be welding. Most metal bodies that lie underwater are steel, but if any other parts around and inside are metals other than steel, you need to be careful and identify them.
You also have to check the weld site and its surroundings to make sure you will be safe in that area, and so are the metal parts you will weld.
Step 3: Preparing the Joints
Of course, here you also need to clean the joint area before welding. But aside from that, you also need to prepare a chamber that you have to put around the joint.
And make sure there are separate chambers for each joint. The chambers have different sizes, so they will match or adjust to the different joint sizes easily.
Step 4: Preparing the Hyperbaric Chamber
After different gases are formed in the chamber, all the water should be pushed out. The gases that replace the water in the hyperbaric chamber depend on the kind of metal that will be welded. The chamber pressure will be a little above the water surrounding the metal joints.
Step 5: Begin Welding
Turn on the power supply to the hyperbaric chamber and set up the welding tool’s electrodes with a port. Then dive into the water till you get to the weld site. Signal a coworker on the surface of the land to turn on the power to the welding tools.
Now you can begin welding the metal joints outside the chamber. After you are done, signal your coworker to shut down the power so that you can check the joints.
If you are involved in construction work in industries that construct metallic structures like cars, airplanes, ships, etc., you will need to have a thorough idea of welding.
But knowing how underwater welding works is helpful, especially for work in ship industries. That’s why the methods and steps above will help you do things properly. Lastly, I would also recommend you to see our reviews on underwater boat lights.