API 1104 Pipeline Welding: Scope, Qualification Logic, and Exam Traps
What API 1104 Governs
API 1104 is the standard for welding pipelines and related facilities. It covers girth welds in transmission and distribution lines, plus fabrication welds, and it is written for field conditions where joint fit-up, weather, and access are less controlled than in a shop. A candidate must know that the standard governs procedure qualification, welder qualification, production welding, inspection, and acceptance criteria as one linked system: a qualified procedure does not excuse an unqualified welder, and a qualified welder does not rescue an unqualified procedure.
The Qualification Chain
Understand the sequence. A welding procedure specification is written, then qualified by testing a test joint; the resulting procedure qualification record documents the essential variables proven. Welders and welding operators are then qualified separately, typically by radiographing a test girth weld. Essential variables are the heart of the topic: changes in base metal group, filler classification, wall thickness range, position, or joint design may require requalification. Learn which changes are essential and which are nonessential, because questions love the distinction.
Defects and Acceptance
Know the defect families: incomplete fusion, incomplete penetration, internal porosity, slag inclusions, undercut, high-low misalignment, and cracks. Cracks are never acceptable. Other defects are judged by size, density, and location against defined limits, often with different rules for girth welds in different service conditions.
Traps to Expect
Common traps: confusing procedure qualification with welder qualification; assuming a radiograph passing means acceptance without applying size limits; mixing up which positions require which tests; and forgetting that repair welds need their own qualification and inspection.
Worked Rule of Thumb
If a question says a welder passed a test in the 5G position and then asks about welding in 6G, treat positional qualification as restrictive: qualification in the fixed position does not automatically extend to all positions. Ask instead which essential variable changed, then decide whether requalification is triggered.