This paper will present welding technology and welding consumables for the welding of duplex stainless steel cargo tanks. For assembly welding both SMAW and FCAW are being used and special flux-cored wires have been developed to optimize welding performance in vertical and overhead welding positions. Most of the prefabrication of tank sections is made with submerged arc welding. Procedures using a suitable backing flux and submerged arc flux for one-sided welding are presented. High productivity is combined with high quality of the weld. Procedures using tandem arc welding are compared with single arc welding. In a chemical tanker there are many welds between stainless and carbon steels, and processes, including gravity welding, procedures and consumables are discussed.