What Is Underwater Welding?

Have you ever wondered what underwater welding is?

At Harcan Marine, we know underwater welding is one of the most essential skills in the marine industry. Whether it’s maintaining offshore oil rigs, repairing ship hulls, or reinforcing underwater pipelines, this trade keeps critical infrastructure running. But how does it actually work, what are the types of underwater welding, and what makes it such a challenging profession?

In this guide, we’re breaking down everything you need to know about underwater welding—straight from the experts.

Defining Underwater Welding

Want to know what underwater welding is? It’s a highly specialised skill, essentially combining commercial diving and welding. It plays a key role in maintaining and repairing submerged structures, ensuring the structural integrity of ships, offshore platforms, pipelines and other essential marine infrastructure.

Underwater welding involves performing welding typically in the ocean or other bodies of water. It can be done in two ways:

Wet Welding: Where divers are directly in the water

Dry Welding: Divers are in a hyperbaric chamber to keep the work area dry

But which option is better?

Underwater Welding: Dry vs Wet

Dry welding means the diver is in a large airtight chamber (hyperbaric) placed over the metal being welded. It’s filled with a gas mix (oxygen and helium) that keeps water out, making it the safer option.

For wet welding, welders use electrodes that create a protective gas bubble around the weld, preventing water from interfering with the process.

Unlike dry welding, wet welding takes place directly in the surrounding water, making it a faster and more accessible method for emergency repairs. However, it also comes with more risks, including reduced visibility, rapid heat dissipation that can weaken welds, and increased exposure to electrical hazards. While wet welding is more convenient in time-sensitive situations, dry welding is generally preferred for its higher-quality results and better control over welding conditions.

Is Underwater Welding Dangerous?

When asking, “what is underwater welding?” and “how do you weld underwater?”, it's important to consider the significant risks involved.

Underwater welders face extreme conditions, including low visibility, strong water currents, and high-pressure environments. One of the biggest dangers is electrical shock, as welding equipment must be carefully insulated to prevent accidents in a water-filled workspace. Additionally, welders must be aware of decompression sickness, a condition caused by rapid changes in pressure that can lead to serious health complications.

Proper training, high-quality equipment, and strict safety procedures are essential to mitigate these risks, making professional certification a crucial step for anyone considering this career.

Where Is It Used?

Underwater welders are crucial in keeping the world’s marine infrastructure running.

Offshore oil and gas platforms rely on them for maintenance and repairs, as constant exposure to saltwater can seriously weaken metal structures. In the shipbuilding and repair industry, underwater welders fix everything from hulls to propellers, ensuring vessels stay seaworthy without needing costly dry docking.

Beyond ships and oil rigs, underwater welding is vital for civil infrastructure like bridges and dams, reinforcing underwater sections that would otherwise be impossible to reach. It’s also used in salvage and demolition, where welders help recover or dismantle sunken ships and other submerged structures.

Welders are responsible for assembling pipelines, docks, and even artificial reefs. Their work keeps essential structures safe, functional, and able to withstand the harsh marine environment.

Underwater Welding Diving Essentials

Underwater welding is a highly technical and physically demanding profession that requires both advanced welding skills and commercial diving expertise. But exactly how deep do underwater welders go? Depths can vary depending on the project, with most welders working at depths between 10 and 50 metres.

However, some commercial diving operations, especially those on offshore oil rigs, may require welding at extreme depths, where water pressure and visibility become major challenges. To safely perform these tasks, divers rely on specific underwater welding equipment, including dry suits, commercial diving helmets, and high-powered welding gear designed to function in submerged environments.

Understanding what equipment you need for underwater welding is crucial for efficiency and safety, as welders must be fully equipped to handle the harsh conditions of deep-sea welding while ensuring precise, high-quality results.

So, What Is Underwater Welding?

Underwater welding is a tough, high-stakes job that requires precision, skill, and the right equipment. From deep-sea repairs to critical marine construction, it’s a profession that keeps industries running.

That’s where Harcan Marine comes in. With industry expertise and a commitment to safety and quality, our team has the skills and experience to handle even the most challenging underwater welding projects. When it comes to marine maintenance and repairs, leave it to the experts at Harcan.