Underwater Welding: Techniques, Safety & Industrial Applications

Underwater, or hyperbaric, welding is a highly specialized technique for welding underwater, most often in the sea, and is commonly used to repair things such as pipelines, ships, and oil platforms.

In this article, we’ll take a closer look at the different types of underwater welding techniques, how they are performed, and what they are used for.

What Underwater Welding Is and How It Works

As the name suggests, underwater welding is any welding done below the surface of a body of water; this could be in the ocean or even in a large man-made pool such as those used in conjunction with nuclear reactors.

The basic premise of underwater welding doesn’t differ greatly from welding on land, the main considerations being a greater need for shielding gas and much higher safety precautions.

Types of Underwater Welding: Wet vs Dry Techniques

Not all underwater welding is considered “wet”; there are multiple methods of “dry” underwater welding that are facilitated by a hyperbaric chamber. Dry welding often yields better results, at the expense of time and cost.

Wet Underwater Welding techniques: Shielded Metal Arc Welding

Underwater SMAW, commonly referred to as stick or arc welding, works by using a consumable metal electrode with both a flux and wax coating.

The flux, much like normal SMAW, burns off to create a gaseous shield to prevent oxidation. The wax prevents the flux from being damaged when it contacts the water.

Wet Underwater Welding Techniques: Flux Cored Arc Welding

FCAW is another commonly used method for welding on land, whereby a consumable wire is fed from a reel through a handheld torch, and a copper contact tip at the end of the torch allows the passage of current through to the workpiece.

Similar to underwater SMAW, the flux burns to create shielding gas; different types of flux-cored wire are used for different materials, but all create a large amount of gas to protect the welding pool from the water.

Dry Underwater Welding Techniques: Habitat Welding

Habitat welding involves a pressurized chamber to enable welding to be completed in a relatively dry environment, enabling better quality welds with a greater ability to do specialized or difficult jobs.

Underwater welding habitats can often accommodate multiple personnel, allowing helpers to work alongside the welder, speeding up the task.

When habitat welding, there is much less restriction on the type of welding that can be used. For instance, MAG (metal active gas) and GTAW (gas tungsten arc welding) are both commonly used in habitat welding, as and when the job requires.

Dry Underwater Welding Techniques: Dry Spot Welding

In a similar fashion to habitat welding, dry spot welding involves a watertight, pressurized container. However, instead of being big enough to fit multiple people inside, it is only slightly bigger than the work area.

The welding electrode is passed through a specially sealed hatch, and the welder views the weld pool through a viewing window.

Safety Precautions, Risks, and Certification Requirements

Even welding on land requires stringent safety precautions to avoid things such as burns and fume inhalation. Underwater welding adds extra dangers, including electrocution and drowning.

The key dangers presented to underwater welders are

• Electric shock – the conductivity of salt water especially means extreme care is needed
• Decompression sickness – at any serious depth, divers must remain “in saturation” to avoid decompression sickness; this is a particular danger if an accident occurs underwater.
• Explosions – many welding processes give off hydrogen, an extremely flammable gas, and preventing the buildup of this is crucial.
• Drowning – dealing with bulky and heavy equipment, as well as diving gear, makes the risk of drowning much higher than in normal diving operations.

Underwater Welding Certification

Underwater welders will typically hold both advanced diving and welding qualifications, with specialized certifications in certain fields, such as underwater pipelines, oil rig repair, etc.

AWS D3.6M is the North American standard for underwater welding, with CSWIP 3.1U being the most widely used underwater weld inspection standard.

Other specialized courses are available throughout North America and Europe for both dry and wet underwater welding.

Tools, Equipment, and Technology Used in Underwater Welding

Alongside the specialized equipment for creating diving habitats and diving gear, underwater welding uses a few specific tools and types of technology not seen in the average welding shop:

• Electrically insulated and waterproof electrode holders
• Diving helmets with built-in welding screens
• Pneumatic or hydraulic cutting and grinding tools
• Underwater welding rods, with special coatings
• A high-powered DC welding machine, with a knife switch safety cutoff

Industrial Applications and Career Opportunities in Underwater Welding

Anywhere there is infrastructure underwater, there will be a need for underwater welders at some point. Common industrial uses include in and around oil pipelines, oil rigs, bridge and tunnel construction and maintenance, and ship repair.

Underwater welding is a highly specialized field with career opportunities all over the world. Those holding the appropriate certifications can make a very good living, with salaries more than doubling that of a traditional welder.

Saturation divers who can weld (those who spend extended times underwater) can earn even more still, especially if they are multiskilled, e.g., being certified in welding, weld inspection, and more.