Weld pass vs weld layer: meaning and how to check it
A weld pass is one trip of the arc or flame along the joint, leaving one bead behind. A weld layer is one level of weld metal in a multipass weld, and it can be made of a single pass or several passes laid side by side. Count passes to track the welding; count layers to track the build-up.
Use this diagram
How to tell passes from layers
- Count the beads. On an etched cross-section, each bead outline is one pass. In the drawing above there are eight.
- Group them by height. Beads sitting side by side at the same level form one layer. The drawing has four: the root, two fill layers and the cap.
- Name the passes by job. The root pass goes in first and forms the root. Fill passes build the joint up. Cap or cover passes finish the face. Some procedures add a hot pass right after the root to burn out trapped slag.
- Check the bead style. A stringer bead runs straight with little side-to-side motion. A weave bead swings across the joint, so one weave pass can fill a layer that would take two or three stringers.
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Definitions and Terminology
A fatigue crack in a cyclically loaded fillet-welded attachment started along the line where the surface of the weld blends into the flange plate. At which weld feature did the crack start?
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Common mix-ups
- Pass versus bead. The pass is the act of welding along the joint once; the bead is the metal it leaves. In practice the words are used together, but the pass is the action.
- Layer versus pass in a WPS. A procedure may control whether a layer is made with one pass or several, or cap the width of a weave. Read what the WPS says rather than assuming one pass per layer.
- Root pass versus root. The root pass forms the weld root, but the root is a location and the pass is a bead.
- Interpass work. Between passes come cleaning and a temperature check. That's what interpass temperature is about.
- Reheating. Each new pass reheats the beads and the heat-affected zone below it, so pass order changes the metallurgy, not just the shape.
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Passes and layers on the CWI exam
Pass, layer, bead, stringer and weave are terms in Definitions and Terminology, at least 12% of Part A, and the control of them sits in Welding Application and Control, at least 9% of Part A. Part A is closed book.
On Part B, procedure documents set limits on passes and bead style. Procedure and Performance Qualifications is at least 28% of the practical, and checking a record of passes against a WPS is the kind of task that domain covers.
On a D1.1 Part C, single-pass and multipass limits appear in the prequalification rules in Clause 5 and the workmanship rules in Clause 7. Look them up in your own copy.
Practice it
The discontinuity cards in the CWI Part A flashcards tie slag inclusions to cleaning between passes and to a weave that runs too wide. Every term from this page sits in the welding terms glossary.
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Sources
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- AWS bookstore, terminology and symbols listing, American Welding Society. Retrieved 20 Oct 2026.
- CWI Part A Fundamentals Examination Information, American Welding Society, Rev. 03.01.2024. Retrieved 20 Oct 2026.
- AWS B5.1:2025, Specification for the Qualification of Welding Inspectors, American Welding Society, Tables 5.1 and 8.1. Retrieved 20 Oct 2026.
Facts checked 25 October 2026 against the sources listed above. If something has changed, tell us and we will correct it within 2 business days.
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