The reluctance of the industry to use underwater welding technique is understandable considering the following things: - Class, either DNV or have not received LR technique for permanent repairs. There are weld defects which almost always accompanies (porosity, lack of fusion, cracking) these burdensome welding technique for permanent improvement purposes. On improving elements that can be said to be less important, the class was able to accept it as a conditional permanent which can be considered as a permanent home in the next inspection found no significant reduction of quality welding.
- AWS D3.6 refers to: 1999 Specification for underwater welding, namely, the best results can be obtained from this technique is a new Class B. Results like this can only be acceptable if only for the purpose welding applications that are less important / critical where lower ductility, porosity is more, the discontinuities are relatively more acceptable. If welding is used usually only applied for purposes that are 'fit for purpose' only.
- The high risk of hydrogen cracking in the HAZ area, especially for material that has higher levels of carbon equivalent of 0.4%. Especially in the North Sea, offshore structures used to use this material.
- Based on existing experience in the industry, welding technique is only performed up into no more than 30 meters.
- Shielded metal process performance arc (SMA) of ferritic electrodes deteriorate with advancing into. Commercial producers also limit the use of electrodes to a depth of 100 meters.
- The nature of the welding results also deteriorated with increasing depth, especially for small ductility and toughness (Charpy impact).
- Due to direct contact with water, the water around the welding area to boil and becomes ionized hydrogen gas and oxygen. Most of the gas is fused into the HAZ area but most of the others will flow into the air. When the flow is retained, there will be a risk of explosion is usually harmful to divers.
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