Welding Procedures, Codes, and Standards
Core Concepts
You must know the role of a Welding Procedure Specification (WPS) and Procedure Qualification Record (PQR), and how welder performance qualification (WPQ) differs from procedure qualification. Study AWS D1.1 structural steel essentials: prequalified joints, essential variables, qualification tests, and inspection acceptance criteria. Recognize other standards (ASME Section IX, API 1104, AWS D1.2 for aluminum) by scope. Understand essential, nonessential, and supplementary essential variables and how a change triggers requalification. Codes govern procedure, personnel, and inspection; standards define symbols, filler metals, and testing methods.
Traps
Frequent distractors confuse WPS with WPQ, or assume a qualified procedure automatically qualifies every welder. Essential-variable changes (e.g., filler metal classification, position, preheat) require requalification; nonessential changes (e.g., travel speed) do not. Remember D1.1 governs steel structures, not pressure vessels (ASME).
Worked Example / Rule of Thumb
Rule of thumb: procedure qualification proves the process, performance qualification proves the person. Changing from vertical-up to vertical-down, or changing FCAW to GMAW, is an essential-variable change requiring a new PQR.