HOW TO CALCULATE FUSION PRESSURE AND TIME

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Issue Time: 2021/12/30 23:27:11

Summary

To properly fuse the thermoplastic pipes and ensure the weld quality, the operator is always obliged to find the right fusion pressure and time under the welding standard which requested by the project.

You could consult with our sales to ask for the welding table for Riyang butt fusion machine (Riyang fusion pressure calculator is on the way), or you could use other fusion pressure calculator APP to work out the pressure and time.This page will indicate how to calculate the fusion pressure and time manually, we will use the standard ISO21307:2017 as an example.

EXAMPLE

Standard: ISO21307:2017 Single Low-pressure

Machine: Riyang Basic Butt Fusion Machine V315

Pipe: OD315, SDR17

Step 1

Check below illustration for single low-pressure fusion jointing cycle.

Key

Xtime

Ypressure

P₁bead-up pressure

P₂heat soak pressure

P₃fusion jointing pressure

t₁bead-up time

t₂heat soak time

t₃heater plat removal time

t₄time to achieve fusion jointing pressure

t₅cooling time in the machine under pressure

t₆cooling time out of the machine

Step 2

Check out the formula of the gauge pressure calculation

Where

GPis the gauge pressure (bar);

IPis the interfacial pressure (MPa);

ACis the total effective piston area, given by the manufacturer of butt fusion machine (mm2)

ASis the interfacial surface area (mm2)

DPis the drag pressure

Note: The interfacial pressure is the amount of force per unit of pipe area required to butt fuse the pipe or fitting ends.

Step 3

Refer to below tables for phases , parameters and values for single low-pressure fusion jointing procedure

Note:

1.(en + 3) This is the cooling time for the butt joint when still in the machine and under pressure. Cooling time may be shortened and should be lengthened depending on ambient temperature (approximately 1% per 1℃)

2.(d) A cooling time out of the machine and before rough handling maybe recommended.

Step 4

Now using all information and formula above we will calculate all values by maximum

e_n= d_n/ SDR = 315mm / 17 = 18.52 mm

P₁= P3 0.19 x {π x (d_n-e_n) x e_n}÷2000 x 10} + 5 (for example) = 21 bar

P₂DP = 5 bar

t₁= bead-up size 0.5 + 0.1 x 18.52mm = 2.3 mm

t₂(13.5 ± 1.5) x 18.52 = 278 s

t₃10 s

t₄3 + 0.03 x 315 = 12.5 s

t₅0.015 x 18.52²- 0.47 x 18.52 + 20 = 16 min

t₆d