Welding of storage tanks

1. Welding procedure qualification

For steel grades used for the first time, process qualification should be carried out in accordance with the current national standards based on the steel grade, plate thickness, welding method and welding materials, etc., to determine the appropriate welding process. Welding procedure qualification adopts butt weld specimens and T-fillet weld specimens, among which butt weld specimens undergo tensile tests and transverse bending tests.

2. Welder requirements

For ordinary welders engaged in electrode arc welding, submerged arc welding and gas electric vertical welding, the assessment is usually conducted in accordance with GB50236-1998. Welders who pass the examination in accordance with the "Detailed Rules for the Assessment of Special Equipment Welding Operators" and obtain the qualification certificates of steel category, group and specimen classification code issued by the quality and technical supervision department can engage in welding of storage tank parts without the need for further examination.

3. Preparations before welding

To ensure the welding quality, the welding equipment should meet the requirements of the storage tank welding construction. For the butt welds of the tank wall with tensile strength σb≥430MPa and plate thickness ≥13mm, low-hydrogen type electrodes should be used for welding. Before welding, the welding materials should be dried and used in accordance with the product manual or the provisions of Figure 1. The low-hydrogen type welding rods after drying should be stored in an insulated cylinder at 100℃ to 150℃ and taken out as needed. It is worth mentioning that sealed flux-cored wires and sealed boxed flux-cored wires, in principle, do not need to be dried again. After drying, flux-cored wires should be cooled to room temperature before use.