Challenges to Develop an Underwater Wet Welding Electrode for "Class A Welds" Classification, as Required in the AWS D3.6 Code

Historically, the procedures for underwater wet welding with coated electrodes are certified (qualified) as "B class" according to AWS D3.6. Because of this, wet welding with coated electrodes is used only in non-structural repairs and emergency situations. The main impediments in achieving "A class" certified wet welds reside in intrinsic characteristics of the coatings types used. The Rutile based electrodes, which are widely used in wet welding due to good arc stability and easy operation, presents low values of elongation in tensile test, the occurrence of defects such as pores and cracks and failure in bend tests. The oxidizing electrodes are used less, due to low arc stability and poor operation, and usually do not reach “A class" certification in qualification procedures for HSS steels because of low values of ultimate strength in tensile test and the occurrence of defects such as cracks in the root pass and lack of fusion that promote failure in bend tests. Another obstacle that arises, regardless of electrode type used, is the failure in hardness test measurements in the HAZ (heat affected zone) that presents values above the limit. This article discusses each of one challenges mentioned above and describes the results obtained with a new wet welding electrode that have achieved weld metal mechanical properties required for "class A" qualification in tests conducted in a hyperbaric chamber in laboratory.