Hawkeye PE Fittings - Manual (Page 2)

Hawkeye Industries Inc. TB-0308-FF
2/5 Hawkeye Industries Inc. Technical Bulletin: FPR IDC and NIDC Fittings
5.2 End Preparation
Ensure that the free end of the pipe does not have any
necking or toe-in. The machined fusion ends of the
fabricated fitting should be free of any deformation, and
should conform to ASTM D 2513 dimensions.
5.3 Cleaning
Use only clean, dry and lint-free non-synthetic cloths for
cleaning fusion surfaces, and areas where fusion equipment
will be secured. Isopropyl alcohol may be used to clean
fusion surfaces. Do not touch or otherwise contaminate
fusion surfaces after cleaning.
5.4 Equipment
Ensure that all fusion equipment is properly calibrated and in
suitable working order. Ensure equipment has adequate fuel
prior to initiating the fusion process.
Use a pyrometer or IR thermometer to double check the
temperature of the heater several times throughout the day.
Use only collets, clamps and equipment designed for the size
of pipe, and for the type of fusion performed. Do not use
excessive force to clamp pipe or fittings.
5.5 Cold-weather Fusion
Fusion in cold weather may affect the fusion parameters. Be
sure to check and test the fusion process in cold weather to
guard against unsatisfactory joints.
Ensure the fusion area and equipment is sheltered from
wind, as well as precipitation and other sources of moisture.
Scrape off any accumulated snow or ice from the fusion area
before starting fusion.
Cold temperature can affect the dimensional and mechanical
properties of polyethylene. Slight OD contraction is possible,
although typically compensated for by fusion equipment.
Polyethylene may have increased stiffness and less
resistance to impact, so increased caution when handling in
cold weather conditions is advised.
5.6 Trial Fusion
Perform trial fusions at least once per day per size of fusion
to requalify the fusion procedure and parameters (See 7.0).
Multiple trial fusions may be required throughout the day if
weather conditions are changing.
6.0 Fusion Procedure
Throughout this section, the terms ‘force’ and ‘pressure’ may
be used interchangeably to describe the force between the
pipe ends, the facing tool and the heater. This does not refer
to the hydraulic pressure of the fusion machine. Be sure to
follow the guidelines of the fusion machine to calculate the
appropriate hydraulic pressures required to attain the fusion
forces / fusion interfacial pressures as described here.
6.1 Initial Parameters and Start-Points
The following values provide a suitable starting point for
setting fusion parameters. These shall be adjusted until a
suitable fused joint can be reliably attained via qualifying
fusion.
Heater Temperature: 210±10 °C [410±18 °F]
Interfacial Pressure: 60 – 90 psi [415 kPa – 620 kPa]
Drag Pressure:
Variable - set per fusion
Cooling time: 30 – 90 sec /in pipe diameter
Regardless of fusion parameters, the cycle is split roughly
into two parts, heating and cooling.
Figure 6.1 The Fusion Cycle
In Figure 6.1, the heating portion includes the initial melt,
and the bead formation areas. Cooling beings immediately
after the heater is removed, the pipe ends are joined.
The interfacial pressure is used to determine the required
force, F
FUSION
, between the pipe and fitting to ensure a
successful fusion.
⎟
⎠
⎞
⎜
⎝
⎛ −
⋅ ⋅ = ⋅ =
2
2
1
SDR
SDR
OD P A P F
INT PIPE INT FUSION
π
[lbf]
Where: P
INT
= Interfacial Pressure [psi]
OD = Actual Pipe OD [in]
SDR = pipe standard dimension ratio
π =3.1415
If the cylinder area, A
CYL
, of the fusion equipment is known,
the hydraulic pressure required (P
HYD
) can be found via the
following:
DRAG
CYL
FUSION
HYD
P
A
F
P + =
[psi]
Do not omit the drag pressure, P
DRAG
when calculating the
required hydraulic pressure. Drag pressures for longer length
of pipe, or pipe made less flexible in cold weather can be on
the order of several hundred psi. Measure the drag pressure
for every fusion joint by noting the minimum required
hydraulic system pressure to move the fusion machine
carriage.