Underwater Welding

Underwater welding plays a crucial role in repairing ships, offshore structures like oil drilling rigs, and submerged pipelines. The process of retrieving damaged components from underwater for repairs can be both costly and time-consuming. This is where underwater welding comes in, offering a cost-effective and efficient solution.

One unique aspect of underwater welding is that it’s performed under elevated pressure conditions. This heightened pressure affects the behavior of welding processes, causing changes like alterations in arc behavior and an increase in arc voltage with rising pressure.

History of Underwater Welding:

The roots of underwater welding trace back to 1932 when Russian metallurgist Konstantin Khrenov first conceptualized the technique. The British Admiralty – Dockyard executed the inaugural underwater welding operation to seal leaking ship rivets.

Innovation in underwater welding continued, with ‘Van der Willingen’ of Holland developing the first waterproof electrodes in 1946.

Types of Underwater Welding:

Underwater welding can be classified into two primary types:

1. Wet underwater welding
2. Dry underwater welding (also known as hyperbaric welding)

Wet Underwater Welding:

As the name suggests, this method is carried out directly underwater, exposing the welder to the water and surrounding elements. Shielded Metal Arc Welding (SMAW/MMAW), commonly known as stick welding with a waterproof electrode, is the predominant welding process employed in these conditions. A constant current welding machine, delivering DC at 300–400 Amps, powers the electrode during these operations. The electrode holders are heavily insulated and designed for water cooling. Additionally, a robust isolation switch is installed in the welding cable to disconnect the welding current when not in use, ensuring safety. Other welding processes that may be utilized include Flux-Cored Arc Welding (FCAW) and friction welding.

Dry Underwater Welding:

Also referred to as hyperbaric welding, this technique involves the use of a specially constructed enclosure or chamber, known as a habitat, to surround both the component and the welder. This chamber, adequately sized to accommodate the welder and component, is filled with a mixture of gases (typically helium and oxygen or argon) to prevent water ingress. Various welding processes may be employed for dry hyperbaric welding, including Shielded Metal Arc Welding (SMAW), Flux-cored arc welding (FCAW), Gas tungsten arc welding (GTAW), Gas metal arc welding (GMAW), and Plasma arc welding (PAW). However, Gas tungsten arc welding (GTAW) or TIG welding is commonly preferred. Dry hyperbaric welding often yields superior weld quality compared to wet welding due to better control over physical conditions, making it preferable when weld quality is paramount. Furthermore, heat treatments such as preheating or post-heating can be conducted during dry hyperbaric welding, enhancing the overall quality of the weld.

Quality of Underwater Welding:

Dry hyperbaric welding generally delivers better weld quality compared to wet welding due to enhanced control over physical conditions. This makes dry welding the preferred choice when superior weld quality is essential. Additionally, heat treatments and non-destructive tests (NDT) are feasible during dry hyperbaric welding, further ensuring weld integrity.

Classes of Welds:

Underwater weld metal properties vary with pressure and cooling rates, resulting in differences from welds made above water. The American Welding Society (AWS) publishes the AWS D3.6 code for Underwater Welding, defining three weld classes: Class A, Class B, and Class C.

Underwater Welding Salary:

Underwater welding offers lucrative career opportunities, with professionals working in construction, surveying, and repair across both freshwater and saltwater environments. Salary varies based on factors such as employer, location, depth of dive, and previous experience, with annual salaries ranging from $20,000 to $300,000.

Underwater Welding Dangers:

Underwater welding poses several hazards, including electric shock, high differential pressure, diving risks, and the potential for explosion. Safety measures such as heavy insulation, isolation switches, and adherence to established protocols help mitigate these risks.

Underwater Welding Certifications and How to Become an Underwater Welder:

To pursue a career in underwater welding, individuals need a commercial diving certificate, welding certification, and relevant safety certifications. The AWS D3.6 code is an internationally recognized standard for underwater welding. To become an underwater welder, one must meet minimum requirements including a high school diploma or GED, swimming ability, commercial diving certification, and AWS Certified Welding Training. Training and certification are essential steps towards becoming a successful underwater welder.