What do P numbers refer to in welding?

P numbers are a classification system used in welding to identify the base metals that can be welded together. This classification helps to streamline the process of selecting the appropriate welding and procedure specifications.

The P numbers categorize materials based on their mechanical properties and composition, ensuring compatibility in welding processes. For instance, they indicate which base metals are compatible for various welding procedures without requiring additional testing for the qualifications of equipment or personnel.

Understanding P numbers is crucial for welders and engineers as it directly impacts the integrity and performance of the welded joints. By adhering to the P number classifications, welders can ensure their work complies with industry standards and regulations, ultimately leading to safer and more effective constructions.