HDPE BUTT FUSION REFERENCE TOOL
Butt Fusion Pressure & Time Calculator
Estimate machine gauge pressure from pipe OD, wall thickness, FX machine piston area and measured drag pressure. Then review the matching ISO 21307:2017 or DVS 2207-1 stage values without mixing the two procedures.
The project WPS, pipe manufacturer instructions and machine documentation remain controlling.
DIRECT ANSWER
How is butt fusion gauge pressure calculated?
For the method shown here, the pipe-wall force is divided by the selected FX machine piston area. The hydraulic pressure contribution is converted to bar and the measured drag pressure P2 is added. With OD 315 mm, SDR 11, piston area 2,000 mm² and drag pressure 10 bar, the estimated P1/P3 gauge pressure is 29.32 bar.
PRESSURE-TIME CYCLE
Read the butt fusion jointing diagram
The original source diagram is retained so the relationship between P1, P2, P3 and t1-t5 remains visible.
Bead-up pressure
Initial pressure used to form the specified bead.
Drag / heat-soak pressure
Measured carriage resistance and the low-pressure heating stage.
Fusion pressure
Pressure held while the joint forms and cools.
Bead-up stage
Continue until the selected procedure's bead criterion is reached.
Heat-soak time
Heating period after the initial bead has formed.
Changeover to cooling
Heater removal, pressure build-up and cooling under pressure.
GAUGE PRESSURE FORMULA
Convert pipe-wall force into machine pressure
P1 and P3 use an interface pressure of 0.15 MPa in this planning calculation. The measured drag pressure P2 is added after the hydraulic contribution is converted to bar.
Interfacial pressure
0.15 MPa.
Outside diameter
Pipe OD in millimetres.
Wall thickness
OD ÷ SDR or a manual value.
FX piston area
Workbook value in mm².
Measured drag pressure
Site resistance in bar.
PARAMETER COMPARISON
Switch between ISO 21307:2017 and DVS 2207-1
The two procedures are separated into switchable blocks. Select one standard and use only its pressure and timing requirements.
ISO 21307:2017
Single low-pressure fusion jointing
Use the phase formulas with wall thickness en and outside diameter dn. Select the maximum heater removal time from the source Table 2.
OD 315 / SDR 11 EXAMPLE
ISO calculated values
The supplied PDF example uses 2,002 mm². The FX-315 calculator uses 2,000 mm² from the FX workbook.
- P1 / P3
- 29.32 bar
- Minimum bead
- 3.4 mm
- t2 heat soak
- 344-430 s
- t3 removal
- ≤ 16 s
- t4 pressure build
- ≤ 12 s
- t5 cooling
- ≥ 19 min
DVS 2207-1
Heated-tool butt welding of PE-HD
The displayed ranges follow the source table's wall-thickness bands at approximately 20°C and moderate airflow. Follow the approved WPS when site conditions are outside that scope.
OD 315 / SDR 11 EXAMPLE
DVS band values
Wall thickness is approximately 28.64 mm, so the 26 < en ≤ 37 mm row is used.
- P1 / P3
- 29.32 bar
- Bead-up size
- 3.0 mm
- t2 heating
- 260-370 s
- t3 changeover
- 12-16 s
- t4 pressure build
- 14-19 s
- t5 cooling
- 32-45 min
PRESSURE & TIME CALCULATOR
Calculate values for the selected procedure
Choose a standard, machine, OD and SDR. Machine piston values come from the supplied FusingX workbook and can be manually adjusted for a verified machine configuration.
Calculated P1 / P3 gauge pressure
ISO 21307:2017
[0.15 × π × (315 − 28.64) × 28.64 ÷ 2,000 × 10] + 10.0
Planning estimate only. Verify every value against the approved WPS, current standard and machine documentation.
PRACTICAL GUIDANCE
Butt fusion calculation FAQ
What is drag pressure in butt fusion?
Drag pressure is the hydraulic pressure needed to move the carriage and overcome machine and pipe resistance before fusion force is applied. Measure it for the actual setup and add it as P2.
Why does piston area change gauge pressure?
The same pipe-wall force produces a different hydraulic pressure on machines with different effective piston areas. Use the verified value for the selected FX machine configuration.
Can ISO and DVS values be mixed?
No. Select one approved procedure and keep its bead, heating, changeover, pressure build-up and cooling requirements together.
Does this calculator replace a WPS?
No. It is a planning and cross-checking aid. The approved welding procedure, applicable standard, pipe manufacturer requirements and machine documentation remain controlling.
FUSINGX SUPPORT
Need help matching an FX machine to your pipe range?
Send the pipe OD, SDR, material and site requirements so the FusingX team can recommend a suitable butt fusion machine configuration.