Welding is an important process in the manufacturing of liquid oxygen storage tanks. Therefore, the quality of welding is a significant factor affecting product quality. The main factors influencing welding quality include welders, welding equipment, base materials, welding materials, and welding processes, among which the selection of welding materials is particularly important.
At the standard level, Table 1 of NB/T47015 “Welding Code for Pressure Vessels” lists the recommended welding materials for commonly used steel grades, including submerged arc welding wires and fluxes, electrodes, MIG wires, and argon arc welding wires. This table has solved most of the problems we encountered when we first came into contact with the welding of liquid oxygen storage tanks. However, when we encounter some tricky situations, such as when the commonly used welding materials run out for some reasons and we can’t purchase them in time or the materials used cannot be found in Table 1, how should we choose the welding materials?
The selection of welding materials for liquid oxygen storage tanks generally follows the following principles:
1.When welding carbon steel and low alloy steel together, the welding material should be selected to ensure that the mechanical properties of the weld metal are higher than or equal to those of the base metal on both sides of the welding joint.
2.When welding stainless steel materials, the welding material should be selected to ensure that the mechanical properties of the weld metal are higher than or equal to those of the base metal on both sides of the welding joint. However, it should be noted that its chemical composition should be the same as or similar to that of the base metal. Especially in working conditions with corrosion resistance requirements, more attention should be paid to the requirements of chemical composition to ensure the corrosion resistance of the weld metal.
3.Select in accordance with the requirements of the design drawings. The selection of welding materials for liquid oxygen storage tanks requires a high level of mastery of material knowledge. Here, we only briefly introduce the selection of welding materials used in daily welding. For each specific working condition, we need to have professional welding technicians make judgments based on the actual situation.
