- Hyperbaric welding
Hyperbaric welding is the process of
welding at elevatedpressure s, normally underwater. Hyperbaric welding can either take place in the water itself or inside a specially constructedpressure chamber and hence a 'dry' environment. It is predominantly referred to as "Hyperbaric Welding" when used in dry mode.Hyperbaric welding is used in preference to underwater welding because of the increased control over conditions which can be exerted, such as through application of prior and post weld
heat treatment s. This improved environmental control leads directly to improved process performance and a generally much higher quality weld than a comparative wet weld. Thus, when a very high quality weld is required, dry hyperbaric welding is normally utilised.Limitations
Most welding processes SMAW,
FCAW ,GTAW ,GMAW , PAW could be operated at hyperbaric pressures, but all suffer as the pressure increases. [cite book |title=Richardson, IM |title=Properties of the constricted gas Tungsten (Plasma) Arc at Elevated Pressures |volume=Ph.D. Thesis |publisher=Cranfield University, UK |year=1991] The degradation is associated with physical changes of the arc behaviour as the gas flow regime around the arc changes and the arc roots contract and become more mobile. Of note is a dramatic increase inarc voltage which is associated with the increase in pressure. Overall a degradation in capability and efficiency results as the pressure increases.Special control techniques have been applied which have allowed welding down to 2500m simulated water depth in the laboratory, but dry hyperbaric welding has thus far been limited operationally to less than 400m water depth by the physiological capability of
diver s to operate the welding equipment at high pressures and practical considerations concerning construction of an automated pressure / welding chamber at depth. [cite book |author=Hart, PR |title=A Study of non-consumable welding processes for diverless deepwater hyperbaric welding to 2500m water depth |volume=Ph.D. Thesis |publisher=Cranfield University, UK |year=1999]See also
Underwater welding References
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