Pipe Weld Calculator
Plan a pipe butt weld: the bevel, root face and gap, the weld metal per joint, how many passes it takes, the arc time per joint and the filler for every joint on the job. Pick a pipe by NPS and schedule or enter the OD and wall.
How to Use
- Choose NPS and schedule to pick the pipe from the ASME B36.10M list, or OD and wall for tube and metric pipe.
- Enter the joint prep: bevel angle on each pipe end, root face (land) and root gap. The defaults follow ASME B16.25: 37.5° and a 1/16 in (1.6 mm) root face; take the gap from your WPS.
- Enter the cap height above the pipe and the root bead height inside it.
- Enter the deposition rate and travel speed of your process (they set the size of one pass; for MIG the Wire Feed Speed & Deposition Calculator turns wire feed speed into a deposition rate), the deposition efficiency of the filler, and the number of joints.
- Read the weld metal, passes, arc time and filler. The drawing shows the bevel, the gap and the passes; Show Work has every step.
Worked Example
The groove. NPS 6 Schedule 40 is 6.625 in across with a 0.280 in wall. With the B16.25 bevel of 37.5°, a 1/16 in root face and a 1/8 in gap, the groove is 0.125 × 0.280 + (0.280 − 0.0625)² × tan 37.5° = 0.0713 in² and 0.4588 in wide at the surface. A 1/16 in cap and root bead add 0.0191 and 0.0104 in², for 0.1008 in² in all. Its centroid runs round a 3.211 in radius, so the weld is 0.1008 × 2π × 3.211 = 2.034 in³, or 0.577 lb of steel per joint.
Passes, time and rod. 3/16 in E7018 at 4.8 lb/h and 9 in/min lays a pass of 4.8 ÷ 60 ÷ 9 ÷ 0.2836 = 0.0313 in², so the joint takes 0.1008 ÷ 0.0313 = 3.2, rounded up to 4 passes. The arc time is 0.577 ÷ 4.8 h = 7.21 minutes, and at 72 % efficiency each joint uses 0.801 lb of electrode, 8.01 lb for 10 joints.
The common mistake: putting the included angle into the formula. The 37.5° in B16.25 is the bevel on each pipe end; the two together make a 75° included angle. Using tan 75° in place of tan 37.5° gives a groove of 0.2115 in² instead of 0.0713 in², nearly three times too much weld metal, passes and rod.
Show Work
Formulas
Bevels, Gaps and the Theorem Behind the Volume
The bevel default comes from ASME B16.25, Buttwelding Ends. For walls over 3 mm up to 22 mm (0.12 to 0.88 in) its Figure 2 gives a single 37.5° ± 2.5° bevel with a 1.6 ± 0.8 mm (0.06 ± 0.03 in) root face; walls of 3 mm and less are cut square or slightly chamfered, and walls over 22 mm get a compound bevel. The standard does not set the gap: that belongs to the welding procedure. Lincoln Electric’s guide Welding Pressure Pipelines & Piping Systems gives two common preps: the API 1104 cross-country joint, with a 30° bevel and a 1/16 in land and gap (“penny land, penny gap”), and in-plant vertical-up welding with a 3/32 to 1/8 in land and gap and an inside bead of at least 1/16 in.
Turning the weld cross-section into a volume uses a result credited to Pappus of Alexandria, who worked in the 4th century AD: a shape swept round an axis makes a solid whose volume is its area times the distance its centroid travels. Because a V-groove is wider at the outside, its centroid sits outside the mid-wall, so the weld round a small, thick pipe weighs a little more than the area times the mid-wall circumference would suggest.
Pass sizes, deposition rates and efficiencies in the presets come from the US Navy’s Steelworker Advanced course (NAVEDTRA 14251A): 3/16 in E7018 at 4.8 lb/h and 9 in/min with 72 % efficiency, and E6011 at 4.5 lb/h with 69 %. The pipeline preset uses Lincoln’s rule of thumb of about 12 in/min for the root with a 5/32 in electrode. Use the figures from your own procedure where you have them.
About This Tool
This calculator works out a single-V pipe butt weld from the pipe size and joint prep: the groove, cap and root-bead areas, the weld metal per joint by Pappus’s theorem, the number of passes from your pass size, the arc time per joint, and the filler for every joint on the job. The groove and cap use the same formulas as the Weld Metal & Filler Calculator for plate, wrapped round the pipe. It draws the pipe end and a section through the joint with the bevels, gap and pass layers. The results are estimates for planning: follow your WPS, the code you work to, and the filler manufacturer’s data sheet, and wear eye and face protection, as OSHA’s welding rules (29 CFR 1910.252) require helmets or hand shields for all arc welding.
Everything runs in your browser; nothing you enter is sent anywhere.
Related tools: Metal Weight Calculator, Welding Cost Estimator, and Welding Amperage Chart.
Frequently Asked Questions
What is the standard bevel for pipe butt welds?
ASME B16.25 calls for a single 37.5° ± 2.5° bevel on each end, which makes a 75° included angle, with a 1.6 ± 0.8 mm (1/16 ± 1/32 in) root face, for walls over 3 mm up to 22 mm (0.12 to 0.88 in). Thinner walls are cut square or slightly chamfered, and thicker walls get a compound bevel. The root gap is not in B16.25; it comes from the welding procedure.
What root gap should I use on pipe?
It is set by your WPS. Lincoln Electric’s pipeline guide describes the API 1104 cross-country prep as “penny land, penny gap”, 1/16 in each with a 30° bevel, and in-plant vertical-up welding with a 3/32 to 1/8 in land and gap, holding a 1/8 in (3.2 mm) gap all the way round when there is no backing ring.
How much weld metal is in a pipe butt joint?
Multiply the cross-section of the weld by the distance its centre travels round the pipe. NPS 6 Schedule 40 (6.625 × 0.280 in) with a 37.5° bevel, 1/16 in land, 1/8 in gap and 1/16 in cap and root bead has about 0.1008 in² of weld, and 0.577 lb of steel per joint.
How many passes does a pipe weld need?
Divide the weld area by the area one pass lays down, which is the deposition rate divided by the density and travel speed. At 4.8 lb/h and 9 in/min a pass is about 0.0313 in² (20.2 mm²), so the NPS 6 Schedule 40 joint needs 4 passes. Real procedures often split wide layers into two beads.
How much filler rod will I need?
Divide the weld metal by the deposition efficiency. Stick electrodes lose stubs, slag and spatter: the Navy’s figure for E7018 is 72 %, so 0.577 lb of weld takes 0.801 lb of electrode per joint, and 8.01 lb for 10 joints, before any allowance for practice or repairs.
How do I use the Pipe Weld Calculator?
Just type your numbers. The answer shows up right away — there is no button to press. Change anything and it updates by itself.
Do I need to install or sign up for anything?
Not at all — it runs in the browser with nothing to install and no account. After it loads once, it even works without an internet connection.
Is my information private?
Yes. Everything happens in your browser. Nothing you type is sent to a server or saved anywhere.
Common Use Cases
Ordering electrodes
Ten NPS 6 Schedule 40 joints at 72 % efficiency need about 8.01 lb of E7018, so a 10 lb can covers them with a little spare.
Planning a pipeline day
An NPS 12 joint with a 0.375 in wall and the 30° API 1104 prep holds 1.17 lb of weld, about 15.6 minutes of arc at 4.5 lb/h.
Comparing bevels
On NPS 8 Schedule 80 a 30° bevel cuts the weld metal from 1.87 lb to 1.55 lb a joint compared with 37.5°.
Estimating a spool
Twelve 168.3 × 7.11 mm butt joints MIG welded at 2.9 kg/h take about 1.06 hours of arc in total.
Training welders
The section drawing shows how the 75° groove widens toward the cap, which is why the fill and cap layers carry most of the metal.
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