Underwater welding with the SMAW (Shielded Metal Arc Welding) process has been used for years successfully on many underwater projects. The method
uses a well insulated electrode holder and coated electrodes. Most welding applications use a 7018 series electrode that is coated with wax or a proprietary
plastisized coating. Welding current is normally set to about 10% higher than would be used for welding in an air environment. The recommended polarity is
DCSP (Direct Current Straight Polarity).
A #4 through a #8 welding lens is recommended for use on the helmet or mask due to the poor visibility under water. The rapid heat loss in water dictates the actual welding technique. Stringer beads should be used instead of a weave bead. Fillet welds are recommended over
full penetration welds. Fillet welds will develop approximately 80% of the tensile strength and 50% of the ductility of welds made above water when they are properly made.
Welding underwater using this method requires holding a very close arc.
Watch a short video of an underwater smaw weld being made here:
The fact that water and electricity don't mix makes this process inherently dangerous and requires added safety precautions. The welding current should be turned on and off
from above water with the welding diver in constant communication with the surface crew. Deep divers with metal helmets need to be sure not to ground the helmet to any part of the welding circuit.
Underwater welding requires both extensive diving and welding training for safety. It should never be attempted without training in both disciplines.
A reasonably priced underwater welding course is available on Ebay:
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