Underwater welding

Underwater welding refers to a number of distinct welding processes that are performed underwater.cite book |author=Keats, DJ |year=2005 |title=Underwater Wet Welding - A Welder's Mate |publisher=Speciality Welds Ltd |url=http://www.specialwelds.com |isbn=1-899293-99-X. |Pages=300 ] cite book |author=Cary, HB and Helzer, SC |year=2005 |title=Modern Welding Technology |location=Upper Saddle River, New Jersey |publisher=Pearson Education |isbn=0-13-113029-3 |pages=677-681 ] The applications of underwater welding are diverse—it is often used to repair ships, offshore oil platforms, and pipelines. Steel is the most common material welded.

The two main categories of underwater welding techniques are wet underwater welding and dry underwater welding, both are classified as hyperbaric welding.

For deepwater welds and other applications where high strength is necessary, dry underwater welding is most commonly used. Research into using dry underwater welding at depths of up to 1000 m are ongoing. [cite journal |author=Bennett PB, Schafstall H |title=Scope and design of the GUSI international research program |journal=Undersea Biomed Res |volume=19 |issue=4 |pages=231–41 |year=1992 |month=July |pmid=1353925 |doi= |url=http://archive.rubicon-foundation.org/2596 |accessdate=2008-07-05] In general, assuring the integrity of underwater welds can be difficult (but is possible using various nondestructive testing applications), especially for wet underwater welds, because defects are difficult to detect if the defects are beneath the surface of the weld.

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Wet underwater welding

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Risks

The risks of underwater welding include the risk of electric shock to the welder. To prevent this, the welding equipment must be adaptable to a marine environment, properly insulated and the welding current must be controlled. Commercial divers must also consider the safety issues that normal divers face; most notably, the risk of decompression sickness following saturation diving due to the increased pressure of inhaled breathing gases.cite book |title=US Navy Diving Manual, 6th revision |year=2006 |publisher=US Naval Sea Systems Command |location=United States |url=http://www.supsalv.org/00c3_publications.asp?destPage=00c3&pageID=3.9 |accessdate=2008-07-05 ] Another risk, generally limited to wet underwater welding, is the buildup of hydrogen and oxygen pockets, because these are potentially explosive. Many divers have reported a metallic taste that is related to the breakdown of dental amalgam. [cite journal |author=Ortendahl TW, Dahlén G, Röckert HO |title=Evaluation of oral problems in divers performing electrical welding and cutting under water |journal=Undersea Biomed Res |volume=12 |issue=1 |pages=69–76 |year=1985 |month=March |pmid=4035819 |doi= |url=http://archive.rubicon-foundation.org/3030 |accessdate=2008-07-05] [cite journal |author=Ortendahl TW, Högstedt P |title=Magnetic field effects on dental amalgam in divers welding and cutting electrically underwater |journal=Undersea Biomed Res |volume=15 |issue=6 |pages=429–41 |year=1988 |month=November |pmid=3227576 |doi= |url=http://archive.rubicon-foundation.org/2486 |accessdate=2008-07-05] [cite journal |author=Ortendahl TW, Högstedt P, Odelius H, Norén JG |title=Effects of magnetic fields from underwater electrical cutting on in vitro corrosion of dental amalgam |journal=Undersea Biomed Res |volume=15 |issue=6 |pages=443–55 |year=1988 |month=November |pmid=3227577 |doi= |url=http://archive.rubicon-foundation.org/2485 |accessdate=2008-07-05] There may also be long term cognitive and possibly musculoskeletal effects associated with underwater welding.cite journal |title=Further investigation of possible musculoskeletal and cognitive deficit due to welding in divers identified in the ELTHI diving study |year=2005 |author=Macdiarmid JI, Ross JAS, Semple S, Osman LM, Watt SJ, Crawford JR |journal=Health and Safety Executive |volume=Technical Report rr390 |url=http://www.hse.gov.uk/research/rrpdf/rr390.pdf |accessdate=2008-07-05]

References

External links

* [http://www.hse.gov.uk/diving/ Health and Safety Executive] - Performs research on long term health effects from underwater welding.
* [http://www.twi.co.uk/j32k/protected/band_3/ksdja001.html Process overview at The Welding Institute]