Underwater Welding Guide: Underwater Welding & How it Works

Underwater Welding Guide: Underwater Welding & How it Works

Underwater Welding Guide: Underwater Welding & How it Works

Underwater welding is one of the most interesting and challenging professions in the field of welding. Imagine all the difficulties and challenges that a welder faces while doing his job on land, and then add water to the equation. Because of the unique nature of this profession, underwater welding requires a specific set of skills and equipment. In this article, we will discuss the details of how underwater welding works, its applications, and the risks involved in this type of work.

How Does Underwater Welding Work

Underwater welding, also known as hyperbaric welding, is a technique performed while submerged in water. As you can imagine, welding in an underwater environment is vastly different from welding on land. So, why was this technique developed, and how does it work?

Underwater welding was first developed in 1932 by a Soviet scientist named Konstantin Khrenov. It was initially used to repair ships and other marine structures without the need to dry dock them. However, with advancements in technology and equipment, underwater welding is now used for a wide range of applications, such as offshore oil and gas pipelines, construction of bridges and harbors, and even salvage operations.

Types of Underwater Welding

There are two main techniques used in underwater welding: wet welding and dry welding. As the names suggest, wet welding is done while submerged in water, whereas dry welding is performed in a sealed hyperbaric chamber, allowing the welder to work in a dry environment.

Wet Welding

When people use the term underwater welding, they are usually referring to wet welding. In this method, the welder wears a diving suit and helmet connected to an air supply on the surface. The welding equipment is also attached to the surface by cables, providing power and shielding gas for the welding process.

When the electrode touches the metal to be welded, an electric arc is created, similar to regular welding on land. However, a gas bubble is formed at the same time, which envelops the weld pool and keeps water away from the hot metal. These bubbles are critical to the process as they shield the weld and prevent the surrounding water from conducting electricity.

The downside of these bubbles is that they also limit the view of the weld, making it challenging for the welder to see and control the process. They can also cause the weld to cool too quickly, resulting in a weaker weld.

Given these challenges, wet welding is typically used for urgent or emergency repairs, where speed is more important than precision.

Dry Welding

Dry welding is a more complex and costly process, but it produces higher-quality welds. In this method, the welder works in a hyperbaric chamber, which is pressurized to keep water out. The welder can also control the atmospheric composition inside the chamber to prevent corrosion and improve weld quality.

Without the presence of water, there are no gas bubbles formed during welding, resulting in better visibility and control over the process. Dry welding also allows for preheating of the metal before welding, reducing the risk of cracking.

Since this is almost like regular welding on land, welders can use most of the traditional welding techniques and equipment. However, certain techniques fail if the weld is at excessive depths.

Where is Underwater Welding Used?

Wet welding is commonly used in marine industries due to its cost-effectiveness and quick turnaround time. Welding a damaged ship or pipeline underwater is often much cheaper than bringing it to the surface for repairs. This is especially true for deep-sea operations, where the cost of lifting and transporting equipment can be high.

Here are some common applications of underwater welding:

Ship Repair: Ship repair is one of the most common uses of underwater welding. Whether it’s a minor hull repair or a significant structural fix, underwater welders ensure ships remain seaworthy without the need for dry docking.

Oil Rig Maintenance: Oil rigs often operate in harsh marine environments, requiring constant maintenance. Underwater welding is used to repair and maintain these massive structures.

Infrastructure Development: From underwater pipelines to bridge supports, underwater welding plays a large role in developing and maintaining underwater infrastructure. This includes repairing leaks, reinforcing structures, and installing new components.

Given the inherent risks of this trade, underwater welding is usually only carried out in shallow waters. This limits its use in certain situations, such as deep-sea oil rig maintenance or repair. However, with advancements in technology and training, it is becoming more widely used in deeper waters as well.

Equipment and Techniques Used in Underwater Welding

The equipment and techniques used in underwater welding depend on the type of welding being performed and the water depth.

Wet Welding Equipment:

  • Welding Machine: The welding machine used for wet welding is similar to a standard above-water welder but with additional waterproofing measures. These machines only use direct current (DC) for welding. This allows for a stable arc even in the highly conductive seawater environment. A switch is also installed on the surface so the welding operator can turn the current off when it is not needed.
  • Electrodes: Wet welding electrodes are similar to traditional welding rods but with additional waterproof coatings. They also have a higher iron content for increased arc stability and reduced risk of weld cracking.
  • Welding Helmet: A specialized welding helmet protects the welder’s eyes from the bright arc. It includes a face shield and a filtered lens that can be adjusted to different shades to improve visibility underwater.
  • Diving Equipment: Since wet welding is performed while submerged, specialized diving equipment, such as a wetsuit, scuba gear, and oxygen tanks, is necessary for the welder’s safety.

Wet Welding Techniques:

  • Shielded Metal Arc Welding (SMAW): Also known as manual metal arc welding, this is the most common technique used in wet welding.
  • Flux-Cored Arc Welding (FCAW): This method uses a continuously fed tubular electrode filled with flux, which creates a shielding gas around the weld area to protect it

These techniques require the welder to have proper training and experience to perform them safely and effectively. Steel, specifically carbon or stainless steel, is the most common metal for wet welding.

Dry Welding Equipment:

  • Hyperbaric Chamber: Dry welding is performed in a sealed hyperbaric chamber filled with a mixture of oxygen and other gases.
  • Welding Machine: Similar to the ones used for above-water welding, dry welding machines are designed to operate under high pressures and can use both DC and AC currents.
  • Electrodes: Dry welding electrodes do not require any additional waterproof coatings since they are not exposed to water during the welding process.
  • Communication Systems: Due to the isolated nature of working inside a hyperbaric chamber, communication systems such as intercoms or radios are installed.
  • Welding Safety Gear: As with any type of welding, safety gear such as helmets, gloves, and protective clothing is essential for dry welding. Due to the high-pressure environment, additional precautions must be taken, including decompression chambers in case of emergency.

Dry Welding Techniques:

Most arc welding processes can be used for dry welding, but the most common methods are:

  • Gas Tungsten Arc Welding (GTAW): Also known as tungsten inert gas (TIG) welding, this method uses a non-consumable tungsten electrode to create the weld. This is the most common method used for dry welding due to its precise control and ability to produce high-quality welds.
  • Gas Metal Arc Welding (GMAW): Also known as metal inert gas (MIG) welding, this method creates the weld using a consumable wire electrode and shielding gas.
  • Flux-Cored Arc Welding (FCAW): This method uses a continuously fed flux-cored electrode that creates a shielding gas when it melts, protecting the weld from outside elements.
  • Shielded Metal Arc Welding (SMAW): Also known as stick welding, this method creates the weld using a consumable electrode coated in flux.

Challenges Faced by Underwater Welders

There is a reason why underwater welders get paid well: the job is not easy. It requires specialized training and experience, as well as physical and mental endurance. Here are some of the challenges faced by underwater welders:

Differential Pressure: One hazard is differential pressure, which occurs when there is a difference in pressure between two points underwater. If not managed properly, this can create dangerous situations.

Electric Shock: Electric shock is another risk, given the combination of electricity and water. Specialized equipment and strict safety protocols are used to minimize this risk.

Decompression Sickness: Also known as “the bends,” decompression sickness occurs when a diver ascends too quickly, causing nitrogen bubbles to form in the blood. Underwater welders must follow precise decompression procedures to avoid this potentially life-threatening condition.

Overall, underwater welding requires a high level of skill, physical and mental strength, and strict adherence to safety protocols. It is not a job for the faint of heart, but for those who are up for the challenge, it can be an incredibly rewarding career.

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Underwater welding is a unique and challenging profession that requires specialized skills, equipment, and techniques. It requires not only a profound understanding of welding techniques but also a high level of expertise in diving. Despite the challenges and risks involved, the demand for skilled underwater welders continues to grow as the need for underwater construction and maintenance increases. Whether you’re just starting out in the field or looking to upgrade your welding toolkit, H&K Fabrication is here to support your journey. We offer a wide range of high-quality pipe-fitting tools and equipment to help you get the job done efficiently and safely.