Welding
Number of weld passes calculator
In short
The number of passes comes from the joint section: A = b·t + (t − c)²·tan(α/2) for a single V groove, A = z² / 2 for a fillet weld. Layers of limited thickness, per AWS D1.1, are stacked from the root and split when too wide; you can also start from the area of one pass: n = ⌈A / Ap⌉.
Calculation
Example calculated with the tool’s default values.
Inputs
- Preparation
- Single V
- Thickness t
- 12 mm
- Included angle α (β for single bevel)
- 60°
- Gap b
- 2 mm
- Root face c
- 1.5 mm
- Number of passes
- AWS D1.1 limits (process, position)
- Process
- GMAW or FCAW (135, 136)
- Position (EN ISO 6947 · AWS)
- PA · 1G / 1F · Flat
Results
- Passes
- 2
Worked example
Every value in this section belongs to the example, calculated with the tool’s default values.
Other results of the example
- Layers
- 2
- Groove area
- 87.7 mm²
- Average pass area
- 43.8 mm²
- AWS D1.1 (prequalified WPS): layer ≤ 6 mm, pass split above 16 mm wide; single-pass fillet ≤ 12 mm in PA. Estimate: the WPS sets the actual number.
Step-by-step calculation
Groove area
A = b·t + (t − c)²·tan(α/2)
87.7 mm²
Layers
layers ≤ 6 mm; pass ≤ 16 mm wide
2 layer(s), 2 pass(es)
Layers from the root
| Layer | Passes | Pass no. |
|---|---|---|
| 1 | 1 | 1 |
| 2 | 1 | 2 |
How to use it
- Pick the preparation: square (I), V, Y, double V, single bevel, or fillet weld.
- Enter the thickness t, the included angle α (β for a single bevel), the gap b and the root face c, or the throat a of the fillet.
- Pick the method: AWS D1.1 limits, with the process and the position, or a known area of one pass.
- Read the number of passes.
Frequently asked questions
How do I calculate the number of weld passes?
First work out the groove area, then stack layers of thickness ≤ hmax from the root; a layer wider than wmax is split (AWS D1.1:2015, table 3.6 and note e). Example: 12 mm V at 60°, 2 mm gap, 1.5 mm root face, GMAW flat: A = 87.7 mm², layers ≤ 6 mm, pass ≤ 16 mm wide, so 2 layers and 2 passes.
How many passes for a fillet weld?
The leg length is z = a·√2 and the section A = z² / 2. It takes one pass if z ≤ zmax: 12 mm flat in GMAW or FCAW, 10 mm with a covered electrode, 8 mm overhead. Beyond that, L = ⌈z / zmax⌉ layers and L² passes: the weld triangle splits into L² similar triangles with side z / L.
Which AWS D1.1 limits does the weld pass calculator use?
Layer thickness ≤ 6 mm in GMAW or FCAW (135, 136) and ≤ 5 mm with a covered electrode (111). A layer is split above 16 mm wide flat, horizontal and overhead, and above 25 mm vertical and on pipe. The calculation only uses these limits for processes 111, 135 and 136.
How do I lay out the passes from the area of one pass?
With the "area of one pass" method, the number of passes is n = ⌈A / Ap⌉, with A the joint section and Ap the area deposited per pass: wire speed × wire section / travel speed, or measured on a macro. The passes are then spread over the layers according to their width.
How is the groove area calculated?
Square groove: A = b·t. Single V: A = b·t + (t − c)²·tan(α/2). Double V: A = b·t + 2·((t − c)/2)²·tan(α/2). Single bevel: A = b·t + (t − c)²·tan β / 2. Here t is the thickness, b the gap, c the root face, α the included angle and β the bevel angle.
Limits
Indicative results: the number of passes is a geometric estimate, the WPS sets the actual number. Layer and width limits are those of AWS D1.1:2015 (table 3.6, prequalified WPS), for covered electrode, GMAW and FCAW only. For a double V, passes are split on both sides, with back-gouging per the WPS.
Sources
- Géométrie : Section d’un chanfrein en V, X, demi-V ; triangle du cordon d’angle
- AWS D1.1:2015 : exigences des DMOS préqualifiés : Tableau 3.6 (épaisseur et largeur de passe) (link)