Piping
Isometric piping drawing
In short
The isometric plan describes a pipe line item by item: straights, elbows, tees, branches, reducers, flanges, valves and caps. It gives the dimensioned isometric, numbered welds, the bill of materials and each spool cut length: centre-to-centre − take-outs − root gaps.
Calculation
Example calculated in the app with the default values.
Inputs
- Pipe
- DN100 · 114.3 × 3.6 mm
Results
- Pipe to cut
- 3953 mm
- Spools
- 6
- Welds
- 11
- Pipe mass
- 38.9 kg
Worked example
Every value in this section belongs to the example, calculated with the tool’s default values.
Spool cut list
| Mark | Pipe | From | To | Cut (mm) |
|---|---|---|---|---|
| M1 | DN100 · 114.3 × 3.6 | S1 · Flange 1 | S2 · Elbow 3 | 792 |
| M2 | DN100 · 114.3 × 3.6 | S3 · Elbow 3 | S4 · Tee 5 | 1239 |
| M3 | DN100 · 114.3 × 3.6 | S5 · Tee 5 | Branch end | 293 |
| M4 | DN100 · 114.3 × 3.6 | S6 · Tee 5 | S7 · Ball valve 7 | 442 |
| M5 | DN100 · 114.3 × 3.6 | S8 · Ball valve 7 | S9 · Elbow 9 | 595 |
| M6 | DN100 · 114.3 × 3.6 | S10 · Elbow 9 | S11 · Flange 11 | 592 |
Bill of materials
| Item | Size | Quantity |
|---|---|---|
| Pipe | DN100 · 114.3 × 3.6 | 3.95 |
| 90° elbow 1.5D | DN 100 | 2 |
| Equal tee | DN 100 | 1 |
| Ball valve | DN 100 | 1 |
| Weld neck flange EN 1092-1 type 11 PN 16 | DN 100 | 4 |
| Flat gasket EN 1514-1 IBC PN 16, 2 mm | DN 100 | 4 |
| Stud bolt M16 (8 per joint) | DN 100 | 32 |
Welds
| Mark | Between |
|---|---|
| S1 | Flange 1 / Pipe |
| S2 | Pipe / Elbow 3 |
| S3 | Elbow 3 / Pipe |
| S4 | Pipe / Tee 5 |
| S5 | Tee 5 / Pipe |
| S6 | Tee 5 / Pipe |
| S7 | Pipe / Ball valve 7 |
| S8 | Ball valve 7 / Pipe |
| S9 | Pipe / Elbow 9 |
| S10 | Elbow 9 / Pipe |
| S11 | Pipe / Flange 11 |
How to use it
- Pick the line pipe: outside diameter and wall thickness.
- The calculation runs on the example line: flange, 1000 mm East, elbow to North, 1500 mm, tee Up, 700 mm, ball valve, 900 mm, elbow Up, 800 mm, flange.
- Read the pipe to cut.
Frequently asked questions
What is an isometric piping drawing?
It shows a line in three dimensions on a flat sheet, on axes at 30° (ISO 6412-1 and ISO 6412-2): simplified elbows, marked welds, dimensions on the axis. Lengths run from one reference point to the next: elbow vertex, tee or branch axis, joint plane of a flanged joint, face of an end flange, valve axis.
How are spool cut lengths worked out from a piping isometric?
Each spool is cut to the axis distance between the weld ends of the two neighbouring fittings, minus one root gap per welded end: cut length = centre-to-centre − take-outs − gaps. Take-outs come from EN 10253-2 or ASME B16.9 tables for elbows, tees and reducers, and from EN 1092-1 type 11 (H2 length) for weld neck flanges.
What does the example line give?
DN 100 line (114.3 × 3.6): flange, 1000 mm East, elbow to North, 1500 mm, tee Up (400 mm branch), 700 mm, ball valve (190 mm face-to-face), 900 mm, elbow Up, 800 mm, flange. The result is 6 spools, 11 welds and 3953 mm of pipe to cut. First spool: 1000 − 52 (PN 16 flange) − 152 (1.5D elbow) − 2 × 2 (gaps) = 792 mm.
Which isometric piping symbols are used?
The line is drawn on 30° axes with simplified elbows (ISO 6412-1 § 4.2) and welds marked S1, S2… Spools are marked M1, M2… in the cut list. Valves use the symbols of the Piping symbols reference sheet (ISO 10628-2): gate valve, ball valve, butterfly valve, globe valve and check valve.
What is in the bill of materials?
The pipe in metres, 90° or 45° elbows (or cut elbows) with their radius, equal tees, reducers, valves, caps, EN 1092-1 type 11 weld neck flanges, EN 1514-1 IBC flat gaskets (2 mm by default) and stud bolts, counted per joint. A flange at the end of the line stands alone; in the middle of the line it is a joint of two flanges and a gasket.
Limits
Indicative results. Take-outs come from EN 10253-2, ASME B16.9 and EN 1092-1 type 11 (PN 16 and PN 40) tables: outside the tables, enter the length from the maker's catalogue, as for the valve face-to-face. An elbow turns 90° at most (beyond that, two elbows); a change of direction needs an elbow; a tee branch is square to the line. Set-on branch: longest generatrix L − √(R² − r²), shortest L − R.
Sources
- EN 10253-2:2021+A1:2026 (raccords à souder bout à bout) : Coudes 2D/3D (rayon R), tés égaux (F), réductions (L) ; tableaux Zickwolff, consultés le 08/11/2026 (link)
- EN 1092-1:2018, brides à collerette type 11 (H2) : Zickwolff (DIN EN 1092-1:2018-12), recoupé RoyMech, consultés le 09/11/2026 (link)
- EN 1514-1:2024, joints plats non métalliques (type IBC) : Épaisseur 2 mm : exemple de désignation de la norme (extrait public) (link)
- ISO 6412-2 et ISO 6412-1 : représentation isométrique des tuyauteries : Axes à 30°, coudes simplifiés (ISO 6412-1 § 4.2), soudures repérées ; symboles : fiche Réf. Symboles de tuyauterie (link)
- Géométrie : Longueur de coupe = entraxe − encombrements − jeux ; coude recoupé : R · tan(θ/2) ; piquage posé : L − √(R² − r²) au plus long, L − R au plus court