McElroy 28 - Determining Fusion Pressure; Butt Fusion Pressure Calculation

9 - 1
Determining Fusion Pressure
Variable Definitions
O.D. = Outside Diameter
t = Wall Thickness
 = 3.1416
SDR = Standard Dimensional Ratio
IFP = Manufacturer’s Recommended
Interfacial Pressure
TEPA = Total Effective Piston Area
Formulas
O.D.
t = ------------
SDR
AREA = (O.D. - t) x t x ∏
FORCE = AREA x IFP
(O.D. - t) × t × ∏ × IFP
GAUGE PRESSURE = ----------------------------------------------- + DRAG
TEPA
Example
Pipe Size = 8" IPS
O.D. of Pipe = 8.625
DRAG = as measured in PSI (for this example use 30 PSI)
SDR of Pipe = 11
Recommended Interfacial Pressure = 75 PSI
Using a Model 28 Fusion Unit
O.D. 8.625
t = ------------- = --------------- = 0.784
SDR 11
TEPA = 4.710 (From Table)
(O.D. - t) × t × ∏ × IFP
GAUGE PRESSURE = ----------------------------------------------- + DRAG
TEPA
(8.625. - .784) × .784 × 3.1416 × 75
GAUGE PRESSURE = ----------------------------------------------------------------------------------- + 30 PSI = 338 PSI
4.710
TX02893-10-12-10
Fusion High Force Medium Low Force
Model (Standard) Force (High (Extra High
Velocity) Velocity)
28/250 4.71 - 1.66
412 11.78 6.01 3.14
618 11.78 6.01 3.14
824 29.44 15.32 9.45
1236 29.44 15.32 9.45
1648 31.42 14.14 -
2065 31.42 - -
1600 31.42 14.14 -
Total Effective Piston Areas