The design and performance tests of customized water-proof welding rods for local-dry underwater welding

Local-dry technology, used for complex structures like KTY connections, especially for that is with limited space to weld, put forward requirements on operational flexibility that can be met by shielded metal arc welding (SMAW). Thus, in the present work, local-dry SMAW (LD-SMAW) was proposed to attempt to repair cracks on the KTY connections, in which the design of customized water-proof welding rods for LD-SMAW is particularly vital to guarantee the weld quality. Commonly used water proofers in the market and commonly used welding rods on land were selected for fabrication of customized water-proof welding rods for local-dry underwater welding. Their performances were compared in terms of amount of welding fume, the water absorption, and the diffusible hydrogen content in the molten metal. Experimental results showed low-hydrogen welding rods (LB-52U for root pass; CHE58-1 for filling and cap passes) and inorganic water proofer (Nano water proofer), which introduce minimum content of carbon and hydrogen, are superior materials for making water-proof welding rods. The water absorption of the customized water-proof welding rods, which were made in dry glove box protected by Argon, was less than 0.1 g in 2 min. And the diffusible hydrogen content in the molten metal was less than 9 mL/100 g, which can effectively decrease or eliminate the cold cracks.