What is the purpose of back-up plates in container repairs?

The primary purpose of back-up plates in container repairs is to reinforce structural integrity. When welding repairs are made, the back-up plate serves to support the material being welded, particularly in thin sections, ensuring that the weld adheres properly and maintains strength and durability in the repaired area. This additional support is crucial because it helps to prevent burn-through during the welding process and stabilizes the joint being welded, which is particularly important for maintaining the container's overall structural integrity after repairs.

While back-up plates may play a secondary role in assisting with the positioning of an insert during welding, their main function is focused on providing strength and ensuring that the repair can withstand the stresses encountered in service. This correlation of purpose highlights the crucial role that back-up plates play not just in the mechanics of welding but in the overall safety and functionality of the container.