KEVOS® MAKEOS · Fabrication
Butt Weld Quantity and Cost Check (Groove Area, Weld Metal, Arc Time, Cost against Quote)
For a butt weld with a V, double-V, bevel or square preparation, how much weld metal, filler and arc time does it take, what does it cost, and does my quoted price cover it?
Quantity and cost of a full-penetration butt (groove) weld: the groove area from the plate thickness, preparation, groove angle, root gap and root face, the weld cap area on one or both faces, the weld metal mass per metre and in total, filler wire from the deposition efficiency, arc time from the deposition rate, paid time from the operating factor plus other time per metre, and labour, filler and shielding gas cost (as the weld cost tool, with groove geometry in place of the fillet), against the price quoted for the welding.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Joint preparation | choice | Edge preparation of the joint, from the drawing or welding procedure. |
| Plate thickness | mm | Thickness of the plates being joined. |
| Groove angle (included angle for V, bevel angle for single-bevel) | ° | Included groove angle for single- and double-V; the bevel angle on the one prepared plate for a single-bevel. Not used for a square butt. |
| Root gap | mm | Root gap between the plates. |
| Root face | mm | Root face (land) left unbevelled at the root. |
| Cap reinforcement height | mm | Height of the weld cap above the plate surface. |
| Cap overlap past each groove edge | mm | How far the cap spreads past each edge of the groove. |
| Weld caps | choice | Whether there is a cap on one face or on both (double-V and back-welded joints). |
| Weld length | m | Total length of this weld. |
| Process and rates | ||
| Weld metal density | g/cm³ | Density of the weld metal (steel about 7.85). |
| Deposition rate | kg/h | Deposition rate of the process at the chosen settings. |
| Operating factor (arc time ÷ paid time) | % | Arc-on time as a share of paid welding time. |
| Deposition efficiency | % | Share of the filler bought that ends up in the weld. |
| Labour rate | AUD/h | Charge-out or labour rate per hour. |
| Filler price | AUD/kg | Price of the filler wire or electrodes. |
| Shielding gas flow | L/min | Shielding gas flow rate (0 for processes without gas). |
| Shielding gas price | AUD/m³ | Price of the shielding gas. |
| Other time per metre (fit-up, back-gouging, grinding) | min/m | Other welder time per metre of weld that is not arc time. |
| Price quoted for the welding | AUD | Price quoted for this weld, on the same GST basis as the rates. |
What each input means
Open an input to see what it is, its units, the worked example and the common mistakes, with a small diagram.
What this means: Joint preparation
- What it is
- The shape the plate edges are cut to before welding, which sets the groove cross-section: a V on one side, a symmetric V from both sides, one bevelled plate, or square edges with only a gap.
- Units and format
- Choose one of 4 options from the list: Single-V; Double-V (symmetric); Single-bevel; Square butt (no preparation).
- Example
- The form opens with “Single-V” selected as a worked example. Choose the option that matches your case.
- Effect on the result
- Changes the groove area formula; for the same thickness a double-V needs about half the bevelled groove metal of a single-V.
- Get it right
- Take it from the drawing or welding procedure; a double-V needs access to both sides and usually caps on both faces.
What this means: Plate thickness
- What it is
- The thickness of the plates being butt welded, which sets the depth of the groove and the gap area through the full joint.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 300 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 12 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- The bevelled groove area grows with the square of the depth prepared, so weld metal and cost rise steeply.
- Get it right
- For plates of different thickness use the thinner plate if it is tapered to match, or check the preparation drawing.
What this means: Groove angle (included angle for V, bevel angle…
- What it is
- For a single- or double-V, the full included angle between the two bevelled faces; for a single-bevel, the angle cut on the one prepared plate. A square butt has no angle.
- Units and format
- Enter a number in °: degrees of angle. The form accepts 1° to 120°. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 60° as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- The groove area rises with the tangent of half the included angle, or of the bevel angle.
- Get it right
- Do not enter the bevel on each plate for a V: a 30° bevel on both plates is a 60° included angle.
What this means: Root gap
- What it is
- The gap left between the plate edges at the root of the joint before welding, which fills with weld metal through the full plate thickness.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0 mm to 50 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 2 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Adds gap × thickness to the groove area and widens the cap.
- Get it right
- Use the gap set at fit-up; a gap larger than drawn adds weld metal through the whole thickness.
What this means: Root face
- What it is
- The flat land left square at the bottom of a bevelled edge, which is not bevelled and so reduces the depth of the V or bevel.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0 mm to 300 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 2 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- A larger root face reduces the bevelled depth, so the groove area falls.
- Get it right
- It cannot exceed the plate thickness; a square butt has no bevel, so this value then has no effect.
What this means: Cap reinforcement height
- What it is
- How far the finished weld cap stands proud of the plate surface, the reinforcement that adds weld metal above the groove.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0 mm to 20 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 2 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Each cap area rises in proportion to its height.
- Get it right
- Use the cap height the procedure allows, not the largest seen; excess reinforcement costs metal and time.
What this means: Cap overlap past each groove edge
- What it is
- How far the cap spreads beyond each edge of the prepared groove onto the plate surface, which with the groove width sets the cap width.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0 mm to 20 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 1.5 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- A wider overlap increases the cap width and so the cap area.
- Get it right
- Welders usually tie in a millimetre or two past each edge; measure a sample weld if unsure.
What this means: Weld caps
- What it is
- Whether the joint has a reinforcement cap on one face only or on both faces, as for a double-V or a joint back-gouged and welded from the second side.
- Units and format
- Choose one of 2 options from the list: Cap on one face; Cap on both faces.
- Example
- The form opens with “Cap on one face” selected as a worked example. Choose the option that matches your case.
- Effect on the result
- Two caps double the cap area added to the groove.
- Get it right
- A single-V welded from one side has only the root penetration on the back, which this tool does not add.
What this means: Weld length
- What it is
- The total length of this butt weld, from which the weld metal, arc time and cost per metre are multiplied up to the job.
- Units and format
- Enter a number in m: metres. The form accepts 0.000001 m to 100000 m. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 6 m as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Weld metal, time and cost rise in proportion to the length.
- Get it right
- Add up every joint with the same preparation and thickness; price different preparations separately.
Process and rates
What this means: Weld metal density
- What it is
- The mass per cubic centimetre of the deposited weld metal, used to turn the weld cross-section and length into a mass.
- Units and format
- Enter a number in g/cm³: grams per cubic centimetre (1 g/cm³ = 1000 kg/m³). The form accepts 0.000001 g/cm³ to 25 g/cm³. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 7.85 g/cm³ as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Weld metal mass, filler, arc time and cost all rise in proportion.
- Get it right
- Steel is about 7.85, stainless about 8.0 and aluminium about 2.7; note the unit is grams per cubic centimetre.
What this means: Deposition rate
- What it is
- The mass of weld metal the process lays down per hour of arc time at the chosen wire size, current and process.
- Units and format
- Enter a number in kg/h: kg/h. The form accepts 0.000001 kg/h to 100 kg/h. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 3 kg/h as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Arc time, labour and gas cost fall as the deposition rate rises.
- Get it right
- Take it from the consumable maker’s data for your settings, not the highest figure in the catalogue.
What this means: Operating factor (arc time ÷ paid time)
- What it is
- The share of paid welding time that the arc is actually burning; the rest goes on setting up, changing wire, cleaning, positioning and inspection.
- Units and format
- Enter a number in %: percent: the number is read as a percentage, so type 8 for 8 %. The form accepts 1% to 100%. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 30% as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Paid time and labour cost rise as the operating factor falls.
- Get it right
- Manual welding often runs at 20 to 40 %; measure your own shop rather than assuming a high value.
What this means: Deposition efficiency
- What it is
- The share of the filler metal bought that ends up in the weld, after losses to spatter, stub ends, slag and fume.
- Units and format
- Enter a number in %: percent: the number is read as a percentage, so type 8 for 8 %. The form accepts 1% to 100%. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 92% as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Filler bought and filler cost rise as efficiency falls; arc time does not change.
- Get it right
- Solid wire with gas shielding is high; stick electrodes lose stub ends and slag, so their efficiency is much lower.
What this means: Labour rate
- What it is
- The hourly cost or charge-out rate of the welder, applied to the paid welding time and the other time per metre.
- Units and format
- Enter a number in AUD/h: Australian dollars per hour. The form accepts 0 AUD/h to 100000 AUD/h. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 95 AUD/h as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Labour cost rises in proportion; usually the largest part of the total.
- Get it right
- Use the same basis as the quote: a charge-out rate includes overheads, a wage rate does not.
What this means: Filler price
- What it is
- The price of the filler wire or electrodes per kilogram, applied to the filler bought rather than to the metal deposited.
- Units and format
- Enter a number in AUD/kg: money per kg. The form accepts 0 AUD/kg to 100000 AUD/kg. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 6 AUD/kg as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Filler cost rises in proportion.
- Get it right
- Use the delivered price ex GST per kilogram, including any extra charge for small spools or packs.
What this means: Shielding gas flow
- What it is
- The shielding gas flow set at the torch while the arc is on, used with the arc time to find the gas used.
- Units and format
- Enter a number in L/min: litres per minute. The form accepts 0 L/min to 1000 L/min. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 15 L/min as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Gas cost rises in proportion to the flow.
- Get it right
- Enter 0 for stick welding or self-shielded wire, which use no shielding gas.
What this means: Shielding gas price
- What it is
- The cost of one cubic metre of shielding gas, including cylinder rental spread over the gas used.
- Units and format
- Enter a number in AUD/m³: money per m³. The form accepts 0 AUD/m³ to 100000 AUD/m³. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 12 AUD/m³ as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Gas cost rises in proportion.
- Get it right
- Convert a cylinder price by dividing by its gas content in cubic metres.
What this means: Other time per metre (fit-up, back-gouging, gri…
- What it is
- Welder time per metre of weld spent on work other than arcing, such as fit-up, tacking, back-gouging the root, grinding and inspection, added to the paid time.
- Units and format
- Enter a number in min/m: min/m. The form accepts 0 min/m to 10000 min/m. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 10 min/m as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Adds labour cost in proportion to the weld length.
- Get it right
- Back-gouging and grinding a double-V root can take as long as welding it; enter 0 only if it is costed elsewhere.
What this means: Price quoted for the welding
- What it is
- The price already quoted or budgeted for this welding, against which the calculated labour, filler and gas cost is compared.
- Units and format
- Enter a number in AUD: Australian dollars. The form accepts 0 AUD or more. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 800 AUD as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Only moves the pass or fail line; the calculated cost does not change.
- Get it right
- Compare like with like: exclude material, cutting and painting if they are not in this calculation.
Method and formulas
- Groove area: single-V g t + (t − c)² tan(α ÷ 2); double-V g t + (t − c)² tan(α ÷ 2) ÷ 2; single-bevel g t + (t − c)² tan β ÷ 2; square butt g t.
- Each cap is a parabolic segment ⅔ W h, with W the groove width at the surface plus the overlap on both sides; weld metal per metre = total area × density ÷ 1000.
- Arc time = mass ÷ deposition rate; paid time = arc time ÷ operating factor + other time; cost = labour + filler (mass ÷ efficiency × price) + gas (arc time × flow × price), as the weld cost tool.
- Example: 103.8 mm² of weld metal, 4.8889 kg in all; the weld costs A$660.53 against a quote of A$800.
Limitations
- Idealised groove and cap shapes; real root penetration, root reinforcement and fit-up variation change the volume.
- Preparation dimensions are entered by you; take them from AS/NZS 1554.1 prequalified preparations or the approved welding procedure.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Price a butt-welded plate or pipe joint
- Compare a single-V with a double-V preparation
- Check a welding quote before it goes out
Who it is for
- Fabrication estimators
- Welding supervisors
- Fabrication engineers
What you get
- Groove area, cap width and weld metal per metre
- Weld metal, filler, arc and paid time
- Labour, filler and gas cost against the quote
Interpreting the result
- The groove area grows with the square of the depth prepared, so for thick plate a double-V or a narrower angle cuts weld metal sharply.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 1438–1441, 1476–1484. Topic reference; no source tables or recommended settings are reproduced.
- AS/NZS 1554.1, Structural steel welding, Part 1: Welding of steel structures — prequalified butt weld preparations; dimensions are not reproduced here.
Learn the Concepts Behind This Tool
These KEVOS® Library readings explain the method this tool uses, with worked examples.
Method explained here · KEVOS® original book
Butt welds: full and partial penetration
In Designing Welded Joints by the Numbers
What it covers: Size butt welds from their effective throat, compare full and partial penetration, see how the groove angle and a double-V change the weld metal, and why reinforcement does not count.
Also in Weld volume, cost and distortion
Method explained here · KEVOS® original book
Joint preparation and fit-up
In Pipe Welding by the Numbers
What it covers: Bevel pipe ends, set the root face and gap, calculate the weld metal a circumferential joint needs, control misalignment and ovality, and tack and clamp the joint so the root can be made right.
KEVOS® tools are screening and decision-support utilities. Verify important financial, engineering, safety, legal or operational decisions using appropriate professional standards and your organisation’s approved data.