Underwater Welding
William Luer
I. Introduction:
Underwater welding has been in use since its discovery in 1932 by Soviet engineer and inventor Konstantin Konstantinovich Khrenov. This discovery would also prove to be extremely useful during the immense destruction of World War II (1939-1945). Welding is the process of uniting or fusing metals by hammering or compressing especially after being rendered soft or pasty by heat. It is most often used with steel, which has a melting point of about 1500o C (2732o F). The history of dry welding can be traced back thousands of years ago to the Bronze Age (3300-1200 BCE) and was also used to create the iron pillar; an 11,900-pound tower erected around 310 CE in Delhi, India.
II. Discovery:
Underwater welding is split into two main categories: dry welding and wet welding. Wet welding is the most common and is performed by a diver clad in a full wetsuit, a 30-pound helmet, and thin rubber gloves. In these rubber gloves, the diver holds a fully waterproof electrode that when charged, heats up the same as it would on land since water is equally conductive. The helmet contains a lense plate that can be flipped up and down over the eyes to protect them from the intense light and also supplies him with sufficient air. Less dangerous DC currents are always used over the common AC currents of your home because they lessen the chance of fatal shock.
Dry welding requires a makeshift habitat that is lowered from a ship, placed around the structure to be fixed, sealed and then drained of all water. This newly made hyperbaric chamber is filled with helium gas and can be operated in just like any other weld on land.
Underwater welding is based off the concepts and ideas of normal welding. In fact many of the wet welding techniques only have a slight variation that allows them to be able to function at an elevated pressure. One of the variations may be to create a helium filled chamber surrounding the structure. There are three other techniques used such as: manual metal arc welding (MMA), flux-cored arc welding (FCAW), and friction welding. MMA welding is the most common process used today. FCAW welding was the technique of choice in the former Soviet Union. Friction welding is used mainly in deep water repair due to the fact that is relatively insensitive to depth changes and is operated by robotic arms up to 10,000 feet under water.
III. Biography:
Konstantin Konstantinovich Khrenov has been credited with the discovery of underwater welding in 1932. Khrenov was born in Borovsk, Russia in 1894. He graduated from the department of electrochemistry of St. Petersburg State Electrotechnical University in 1918. In 1932, he worked as a lecturer at the Moscow Institute of Electromechanical Engineering and the Bauman Moscow State Technical University. His career was dedicated to developing and improving new techniques and equipment.
Due to his dedicated mindset and the extreme aid that underwater welding had towards the Soviet Union in WWII, Khrenov was given the Stalin Prize in 1946.
IV. Impact on the World:
Underwater welding has had a vast impact on the world as we know it. It is used most often to repair ships, oil platforms, and pipelines offshore that have been damaged, most often by hurricanes or explosions. During World War II, ships could be constructed, built, and repaired all without having to leave the water.
This may all sound too good to be true and you’re exactly right. There are three potential risks that may result from underwater welding. The first is electric shock from the electrode the diver is holding. The second risk is for the potential for pockets of explosive gas to be built up as a product of the welding and cutting. The third and final risk has to do with pressure changes. If a diver is to experience too rapid of pressure changes, deadly bubbles of nitrogen will emerge in his bloodstream and kill him.
Due to the high level of expertise required, Global Industries, a leading company in construction, engineering, and support for oil and gas industries, makes trainees undergo years of specialized training. As you can see, underwater welding also gives jobs to people from across the world.
V. Journal Article:
The Journal Article I chose has to do with the effects of wet underwater welding on the fracture behavior of welds. It takes into account the nature of the surrounding fluid having to do with temperature distribution. Inhomogeneous volume changes and thermal residual stresses occur on the weld due to the heating and cooling. A similar weld was performed in both a wet and dry weld scenario in order to see the differences.
In a dry weld, the molten pool of steel that dried to an inhomogeneous volume was 15mm longer than that of the wet weld because the water provides a high cooling rate. The depth and width between the two experiments were nearly identical. In conclusion, the water contact leads to a high cooling velocity and to a high temperature gradient in the vicinity of the weld seam compared to dry welding in air atmosphere.
Video
"Konstantin Khrenov : Define, Explore, Discuss." 1000s of Museums Online : MuseumStuff.com. Web. 12 Dec. 2010. <http://www.museumstuff.com/learn/topics/Konstantin_Khrenov>.
"Konstantin Khrenov : Info, Images, Discussion." Web. 12 Dec. 2010. <http://www.joeinvestoronline.com/library/Konstantin-Khrenov.php>.
Lutz, Lindhost. On the Effects of Wet Underwater Welding on the Fracture Behaviour of Welds 1969: 1-8. Web. 12 Dec. 2010. <http://www.iasmirt.org/SMiRT16/G1969.PDF>.
"Underwater Welding (Knowledge Summary)." TWI - Welding and Joining Specialist. 2010. Web. 12 Dec. 2010. <http://www.twi.co.uk/content/ksdja001.html>.
U.S. Army Operator Ciculars. "Great Welding Hist
ory Information !!" Great Welding History Information. Web. 12 Dec. 2010. <http://www.weldguru.com/welding-history.html>.
"YouTube - Underwater Welding." YouTube - Broadcast Yourself. Ed. The History Chanel. Modern Marvels, 16 Dec. 2008. Web. 12 Dec. 2010. <http://www.youtube.com/watch?v=zt-IcUp82w4>.
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