A well-done underwater wet welding project starts long before a welder diver strikes the arc. In fact, proper prep-work begins at the surface level.
Though it’s less expensive than dry welding, project managers and underwater welders must often determine whether the wet welding project they’ve been requested to perform is even in their range of capability. Small projects require just as much expertise as large ones (just on a different scale).
And then there’s the qualifications: How many divers are trained in underwater wet welding? Do they have the proper equipment for the depth and type of weld? For inspection?
There’s many other factors to think through before even attempting the project.
At the end of the day, underwater welders must remember the bottom line:
Proper inspection provides a solid foundation to your work – no matter what it is.
This is the nature of the construction industry. So what’s to be inspected, and how to you go about preparing for wet welding projects? This guide will give you specific factors to view as you make your own assessments.
Underwater Wet Welding Considerations
Welding topside or underwater is similar when it comes to qualification. Few certifications are transferable.
You must perform the specific weld technique in the specific environment and specific circumstances presented to you. Even so, gaining coded welding qualification from recognized diving schools is a good first step. From here, companies are much more likely to look at you and allow you to inspect welding sites, even if you don’t actually perform the weld right away.
Training first. Qualification second (from recognized training organizations). Experience third. And fourth, and fifth.
There’s some things that can’t be stated on paper, and your employer takes those aspects seriously. Focus on these areas as well:
- Team Player
- Organization Skills
- Taking Initiative
- Progressive Thinking
- Respect Peers and Authority figures
One of the scariest parts of welding underwater? Your surroundings. Environments are completely out of a diver’s control, and they only thing they can do is work with it. It can also have a major impact on diver safety, so the team will look at the waters ahead of time to determine what’s best.
Sometimes underwater welders talk about performing a weld in zero visibility conditions. Technically this is never true, as the brightness from the arc always provides at least a small radius of sight for work. Still, without at least 10 – 25% visibility, welds will turn out mediocre at best. The best welder divers have to have a point of reference to see the parameters, beginning and ending portion of the weld.
Anything different is an excuse for bragging rights. Make sure you have the proper equipment to simulate the right lighting conditions if there’s not enough sun.
Salt versus Fresh
Oceans are actually easier to wet weld in. This has to do with the high salt content in the water. The salt is composed of sodium and chlorine ions, both of which conduct electricity well. When an electric arc is struck, the ions carry the charge and direct it in an efficient manner, much like air in a funnel.
Freshwater is different. When an underwater welder fires up their stinger, the arc behaves more in a more unstable fashion, shooting up bubbles from different directions and connecting more loosely to the metal being welded upon. This isn’t to say freshwater wet welding is impossible – it simply takes more experience and preparation when undergoing the project.
Every weld type has its strengths and weaknesses, and arc blow falls under the weakness of SMAW. It’s broken down into two categories:
Thermal Blow (control): Sporadic temperature and wrong metal mixes are recipes for disaster in your underwater welding. Make sure your weld site is completely cleaned beforehand, and that you’re moving at a solid speed when you begin.
Magnetic Blow (partially control): Here, there’s too many factors to point to a root cause. The built up magnetism causes deflection of your arc current and puddle, and it can push back from the side, behind or in front. It’s always a factor in direct current (the way wet welds are performed).
Your primary uncontrollable variable includes the surrounding environment, though wrong power settings and angle also play major roles. Since magnetic blow almost always happens to some degree, make sure you plan for counter moves to keep your arc and weld site stable.
Underwater welding in heavy current is an out-of-body experience. It’s like a heavy wind, but with more fluidity and less sharpness. It is often the biggest factor on projects closer to the shore, where current is always pushing in an out from the shore. Sometimes you just want to press the “pause” button on the moon (probably a bad idea).
These water currents may carry your electric current with it. If you must perform the wet weld that day, think about putting barriers between you and the water, such as a welding cage. You may even need to enclose your weld, turning it into a partial dry welding project. DC power is always used over AC.
There’s a reason that the majority of underwater welding takes place in shallow waters.
Besides light, water pressure creates significant challenges. High pressures force you to use excess electric cable further down. If you don’t have a high quality connection, you may lose partial or total power during welding. In addition, high pressures may distort your weld equipment and wet welding area, including the pool. In the end, you may need to adjust your weld speed to compensate for some of these variables.
Underwater Welding Equipment
During their careers, underwater welders may use many types of equipment to accomplish their projects from start to finish. Each job is specialized, however, so not all tools are required. The point of the first dive is to inspect your weld site so you’ll know exactly what’s needed for the job.
In any underwater welding project, inspection tools like tape measures, lights, cameras, wire brushes (to clear away areas and provide proper measurement) are often necessary. As with every underwater welding job, you’ll also need the correct stinger and electrodes. Your electrodes will range from 3 – 5 millimeters, with a little leeway in between. Along with waterproof coating, check your electrodes for correct length and inner material (usually carbon manganese or nickel).
A chipping hammer is a great tool as well for clearing away rust and toxins.
That leads us to the metals…
Metal & Construction Types
If the company employing your services doesn’t know what types of metal you’ll be welding together, you might become a little suspicious. Only specific metals work well for joining together underwater. This may happen in the instance of lost building records and blueprints. If your company reps don’t have those specifics, you’ll have to inspect it for yourself and take a sample or recording.
Stick welding is used on four types of metals:
- Cast Iron
- Stainless Steel
Aluminum is a rarity because of its value (though underwater welders have performed projects on it).
Cast iron: Underwater? Probably not.
Stainless steel and steel will be your most common occurrences.
Find out the coding on your steel type, then look up the metal mix to determine which equipment and techniques will work best on them. This process involves a number of evaluations:
- Heat transfer (and pre-heat)
- Gas interferences and hydrogen
- Welding technique used
- Metal constitution
- Electrodes types
- Amount of carbon (higher equals lower welding capabilities)
Project Style & Methods
Simple is better. No matter which underwater welding method you’re using, this statement stands true. The three fundamental types are Back Step, Back Hand and Vertical.
Take a look at how thick your metal gauge is directly over the site. Thinner often lends itself to Back Step. How much of an angle is the pipe or hull? Is there a “t-bone” formation of metal that you’ll be repairing (best for vertical welds on fillet style)?
As you can see, there’s a lot of considerations to take into account. And though you have more experience with one style, it might not work best for this particular weld. If you try to force an underwater weld method that’s not appropriate, you’ll spend twice the time with reduced quality to show for it.
Be patient, and spend time practicing the style that you feel is best in a different setting.
Speed or Safety
When you’re evaluating a site for weldability, you’ll probably see two ways to do it: The blaze and the crawl.
Don’t be fooled by what’s in front of you. Even the most “cut and dry” wet welds may present unforeseen complications.
Spend more time up front, evaluating the weld and planning for anything that would go wrong or unexpected. It will happen. If not on this job, on another.
Part of a Whole
Point your finger at something. How many fingers do you have pointing back at you?
Even if you’re doing an inspection and underwater welding job solo, you always have a full diving team behind you helping in preparation, communication and troubleshooting. Keep your team in mind during every part of the project. Though they may not know how to wet weld, everyone has their own areas of specialty that may be useful in getting the job done.