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Underwater-weldingfor saving while rescuing:SOLUTIONS with Effective, Powerful AdviceShould I take the plunge?
Underwater welding, welding under water, enclosure welding, hyperbaric enclosure welding, wet Underwater-welding, high pressure water jet welding, other welding processes: friction welding, resistance welding, arc welding, tig welding, mig welding, oxyacetylene welding, electron beam welding, laser beam welding, welding techniques, welding information, welding links, welding tips, welding instructions, improving welding results, welding safety issues, joining questions needing answers: these are some of the items developed in this Site for the benefit of interested readers. What is in here for me? Underwater welding, one of the best examples of adapting a well known process to the harsh and dangerous environment of the sea, demonstrates what necessity, ingenuity and continuing efforts could accomplish, mostly to save huge investments in offshore structures that were damaged and needed repair. The advantages are of economical nature, because Underwater Welding for marine maintenance and repair jobs bypasses the need to pull the structure out of the sea and saves much valuable time. If one thinks of Underwater-welding the hull of a ship or of a partially submerged oil drilling tower, one understands that the alternative may be extremely expensive, if at all possible. The limitations of Underwater-welding concern the inevitable bulky and expensive setup to provide the welder with all the support needed, for respiration, for protection from cold, for special welding equipment, for remote surveillance camera, for special non destructive testing. Important AnnouncementSee our New Page on Metals Knowledge for assembling at no cost an Encyclopedia Online, a rich collection of valuable information on Metals, from expert Internet sources.
The main risks for the welder performing Underwater-welding are the potential for electric shock, the possibility of producing in the arc mixtures of hydrogen and oxygen in pockets, which might set up an explosion, and the common danger sustained by divers, of having nitrogen diffuse in the blood in dangerous proportions. Curiously the risk of drowning is not listed with the hazards of Underwater-welding. First there were no demands for quality. Underwater welding was just applied to weld a patch until a more thorough repair could be performed. But as soon as more experience was gained, ambitious individuals and companies joined forces to improve results and to establish achievable specifications.
Let us continue... ... with some more details on Underwater-welding. There are three main ways to perform Underwater-welding. One is to build an enclosure, a pit, around the place of repair and to pump away all the water: that amounts to prepare the conditions for normal welding in air, although the place may be deep under sea level. Another method of Underwater-welding consists in preparing an enclosure to be filled with gas (helium) under high pressure (hyperbaric) to push water back, and have the welder, fitted with breathing mask and other protective equipment, weld quite normally out of water but under pressure. The third is the wet Underwater-welding method, where no attempts are made to dry up the location of welding. Instead the power of the arc generates a bubble of a mixture of gases which lets metal melting and joining occur more or less normally, using specially covered electrodes to avoid that too much hydrogen be absorbed in the weld. The skilled welder must also be a diver, equipped for Underwater-welding, with all the extra equipment and protection a welder must use. There is also a less used method of Underwater-welding which features a special torch which sprays a cone of high pressure water, within which protective gas under pressure insulates the weld location from the water during welding.
The following is the most complete and authoritative Specification concerning Underwater-welding: AWS D3.6M Basic informations and suggestions on this subject can be found by clicking on Taking the Plunge. Note: Let us make it clear at once that Underwater-welding has nothing to do and should not be confused with Submerged Arc Welding wich is a specialized process described in a page on Arc Welding, and which is performed outside water. An Article on Developments in Underwater wet Welding was published In Section 11 in Issue 29 of Practical Welding Letter for January 2006. To read the article click on PWL#029. Note: On the same subject see also a new Page with deeper insight and current developments. Click on Welding Underwater.
We believe that "A Welder's Mate" is essential reading for anyone serious with learning and practicing Underwater Welding, and a useful manual for every surface welder.
We urge our readers to read the first Excerpt by clicking on
We recommend the second edition of this book.
To purchase the New Edition of the Book £22.99 inc P&P £25.99 inc P&P £28.49 inc P&P Other Welding Processes. Even if you are not familiar with Underwater-welding, you certainly know your processes. But how could a different one be selected? You know that there is no universal welding process perfectly adapted and convenient to whatever form and material joining. However in most cases one or more processes may be selected which permit acceptable welds to be performed. How would you select your process? Is the process you use the best one? How would you improve on it? What is the best process? Tip!: The "best" process is the the least expensive and available one that can be used to produce acceptable welds performing the functions of strength and stability required for the joint. If you are looking... ... for information on other welding PROCESSES, chances are you will be able to find what interests you just by browsing here. However, if you do not find what you look for, no problem. Any questions or comments or feedback? Write them down and send them to us by e-mail. Click on the Contact Us button in the NavBar at top left of every page. The following descriptive information of only the most important processes is provided for general orientation leaving more specific details to be found in the underlined referenced pages hereafter. For practical purposes of designation, processes are usually divided between PRESSURE and FUSION WELDING. In the first type, pressure is always applied, with or without external means to provide heat, while melting temperature may or may not be reached. In the second type melting temperature is usually reached locally without the use of pressure. Did you know that... Welding history recognizes FORGE WELDING, which belongs to the pressure category, as one of the oldest processes performed in the blacksmith's shop well before the twentieth century. Do you agree that it could be a very interesting experience for school-children to watch, if somebody wanted to revive the practice for a show? Would you organize that for your community? This joining is achieved when two elements, usually steel bar ends, heated to white temperature in a coal burning forced air furnace, are brought rapidly together and hammered thoroughly on the anvil to expel any oxide layer which might be present and to work them intimately to complete union. An Article on Forge Welding was published in section 2 of Issue 35 of Practical Welding Letter for July 2006. To see the article click on PWL#035.
Similar but different... A modern sophisticated version, called FRICTION WELDING was developed, which has some important applications, especially for mass production or for specialized repairs. In general it is not for job-shops, but small shops dedicated only to this specialty may thrive, given the right conditions. A description of the process follows in the dedicated page: click on Friction Welding Process. Most important in the pressure category are RESISTANCE WELDING processes, further divided into spot, seam and projection welding, frequently highly automated. Many of our everyday household items and car bodies are held together by resistance welds. How would you decide if it is the right solution for your welding problems and how could you improve on it? These processes share the fact that heating is produced by the resistance to the flow of a concentrated high electric current which is made to pass locally between special copper electrodes holding the elements to be welded together under applied pressure. For more details click on Resistance Welding.
On the other hand... Of the fusion welding processes developed in the twentieth century, and acclaimed as a real and important breakthrough, GAS WELDING, using an open FLAME, is probably one of the earliest of modern welding history. In this manual process the heat required for local progressive melting is provided by the flame of combustion of acetylene gas (other gases were tried and abandoned) with oxygen. A filler metal rod of appropriate composition may or may not be used as required. In preparation for Underwater-welding there may be a need to perform flame cutting using hydrogen gas. (Flame welding is not used). See details in Cutting. ARC WELDING represents a family of quite different processes, each one best adapted to its particular application niche. In these processes the energy required for melting the metals is provided by an electric arc, struck between the electrode, held by the torch, and the workpiece, usually clamped on a welding table. Underwater-welding is mostly performed by variations on this process, taking into account the particular environmental and operator's requirements. In the general case, the electrode is either consumable, melting to provide filler material, or non consumable, being made from a refractory tungsten alloy. In this case, when needed, filler metal is provided separately either from a manually held filler rod or from a reel fed continuously in automatic or semi-automatic equipment. The needed protective atmosphere is provided by gases from decomposition processes of suitable materials, enrobing the electrodes (sticks) or included in the core of specially prepared (flux cored) filler wires. Otherwise a stream of inert gas like Argon or carbon dioxide (CO2) or mixtures thereof is continuously supplied to the molten pool through the torch.
An Article on Ultrasonic Welding was published in the April 2004 Issue No. 08 of Practical Welding Letter. To read the Article click on PWL#008. An Article on Explosive Welding was published in the May 2004, Issue No. 09 of Practical Welding Letter. Click on PWL#009 to read it. An Article on Diffusion Bonding was published in the June 2004 Issue No. 10 of Practical Welding Letter. Click on PWL#010 to read it. An Article on Magnetic Pulse Welding was published in the Feb. 2005 Issue No. 18 of Practical Welding Letter. To see the article click on PWL#018. An Article on How to start Process Comparison was published on the May 2005, Issue No. 21 of Practical Welding Letter. To read the article click on PWL#021. An Article on Welding in cold Weather was published in section 3 of the issue 30 of Practical Welding Letter. To see the article click on PWL#030. An Article on Friction Stir Welding was published in the Contribution Department (11) of the issue 32 of Practical Welding Letter for April 2006. To read it click on PWL#032. An Article on Friction Stir Welding was published (2) in Issue No. 47 of Practical Welding Letter for July 2007. Click on PWL#047 to read it. To receive regularly the Letter as it is published please subscribe. Last but most important... High Energy Welding processes are more specialized, in that they require sophisticated equipment, mostly precisely computer controlled, and are used for specific and important applications like aerospace, outer space, submarine (but not Underwater-welding!) and nuclear, or for mass production of delicate small implements. Note: See also a new Page with deeper insight and current developments. Click on Welding Underwater .
Any questions or comments or feedback? Write them down and send them to us by e-mail. Click on the Contact Us button in the NavBar at top left of every page.
For any one of the following Processes click on the underlined item:
Welding Underwater Processes
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