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 2.
Threading:
Threading
of Sch. 80 or 120 pipe only is recommended. Sch. 40 pipe is not
recommended for threading. Pressure ratings of threaded pipe are derated
by 50% from the plain end pressure rating due to thread depth.
3.
Solvent Welded Joints:
A.
Cut and bevel pipe per Procedure 1. above.
B.
Condition pipe and fittings to the same temperature. Avoid direct sunlight.
C.
Check dry fit of pipe and fitting after wiping with a clean, dry, lint
free cloth- Pipe should enter fitting about 1/3 to 2/3 depth without
resistance.
D.
Mark the depth of the socket on the pipe end to be joined.
E.
Using a clean brush, apply a liberal coat of P-72 solvent cement
to the pipe end over the primed area, making certain the end is completely
covered. Then do the same to the socket of the fitting, using
a circular motion, finishing with straight outward brush strokes
to prevent excessive cement in the socket. For larger sizes, 4
" (100mm) and above, two persons are required to work simultaneously
on the pipe and fitting to make sure of a fast connection.
Primer:
Some
users and fabricators prefer the use of a primer, (this is generally
due to applications involving higher temperatures and pressures). Where
a primer is desired the following procedure applies. Apply primer (see
primer note) to the socket fitting until the surface softens. Use a
natural bristle brush half the pipe size. The purpose of the primer
is to dissolve and penetrate the surface of the socket and pipe.
Repeated applications may be necessary. Then immediately do the same
to the end of the pipe to the mark that denotes the depth of the
socket, again apply the primer to the socket of the fitting. Then
apply solvent cement
While
both surfaces are still wet, insert the pipe into the socket while turning
the pipe 1/4 turn. Make certain that the pipe reaches the bottom
of the socket. For 4 " (100mm) and larger pipe, two or more
persons may be required to push the pipe into the socket. The
application of the solvent cement and the insertion of the pipe
into the fitting should take approximately one minute for pipe up to
4 " (100mm) in diameter and up to 2 minutes for larger pipe
diameters.
Hold
the joint together for approximately 30 seconds (longer for larger
size pipe) until the pipe is firmly set in the socket bottom. Remove
any excess cement on the outside of pipe and fitting. Where accessible,
inside of pipe and fitting must be wiped clean. Allow the joint
to cure and become completely set before handling for installation.
 4.
Pipe Supports:
It
is important to follow the pipe support spacing guidelines given. This
will prevent sagging of the pipe. Pipe supports should be equal in length
(minimum) to the diameter of the pipe, and should form at least a 120¡
"saddle". Avoid point loads. Saddles should be smooth and
lined with rubber if necessary to prevent any scratching or nicking
of the pipe exterior. P-72 pipe must be allowed to move longitudinally
and circumferentially, and therefore cannot be clamped down tight. If
it is necessary to completely clamp P-72 pipe, a minimum 1/4"
(6mm) thick rubber gasket should be placed between the pipe and clamp
and minimal tightening force used. Heavy valves and other accessories
should be independently supported so as not to place any stresses on
the P-72 piping from this weight or operating torques.
5.
Expansion / Contraction Systems:
Due
to the high thermal expansion and contraction coefficient of all plastic
pipe, care must be taken to design a system to accommodate the changes
in length of P-72 piping. Expansion loops and/or special anchored expansion
joints for plastic pipe should be used. Consult Prince Rubber &
Plastics for more detail. Consider that many commercially available
expansion joints are not suitable for plastic pipe due to the
high forces required to move them. Note that P-72 pipe can expand
4" per 100' per 100¡ F (100mm per 30.2m per 56¡C) temperature rise.
6.
Hydrostatic Pressure Testing:
Do
not use air or compressed gas to pressure test! It is recommended to
wait at least 48 hours up to and including 4" (100mm) pipe after
solvent cementing, and 72 hours for 6" (150mm) pipe and larger,
before pressure testing. The hydrostatic pressure rating of a piping
system must be considered as the pressure rating of the lowest pressure
rated component of the system.
7.
Welding P-72:
P-72
can be easily rod welded with hot air, and butt-welded with a heated
plate welder, producing strong joints. (Special instruction available).
8.
Storage and Handling:
All
plastic pipe, including P-72 is relatively fragile compared to metal
pipe. Do not drop plastic pipe, especially at low temperatures. Store
pipe neatly and straight on proper supports, and do not walk on it or
pile heavy loads on it. Whenever possible, inside storage is recommended.
P-72
Pipe and Fittings with FRP Overwrap
It
is sometimes desirable to overwrap P-72 pipe
and fittings with FRP (Fiberglass Reinforced
Plastic) for:
a)
Increased durability and structural strength.
b) Higher pressure ratings than unsupported P-72 can achieve.
c) Reinforcing large bore pipe and fittings when using a P-72 liner.
d) Reinforcing piping systems that may be subject to excessive outside
forces.
e) Reinforcing special outlets.
f) Increased support spacing.
P-72
is available with filament wound or hand lay-up FRP reinforcing
depending on the application. Usually the P-72 will be considered a
"liner" inside the FRP and the FRP will be considered
as the structural load bearing part of the "dual -laminate".
In this case, it is best to use a thin liner of 3/16" or 1/4"
thickness P-72 with the FRP, to prevent potential cracking at
welds, or in the P-72, all due to the difference of coefficient of expansion
between P-72 and FRP. Recent data developed has shown that the thin
wall liner of P-72, whether extruded or formed from sheet, performs
well with either filament wound or hand lay-up FRP overwrap. P-72 is
available overwrapped from 2" (50mm) and up in size.
Flanged
and solvent cemented FRP reinforced P-72 can be used as a complete
piping system. We can assist you with P-72/FRP dual-laminate
specifications based on your requirements such as:
a) Pressure/Temperature
b) Structural strength.
c) Support spacing.
d) General engineering detail.
Note:
Primer:
Prince Rubber & Plastics Co. Inc, can make available a primer
for resale in quart containers. However, if you wish to make
up your own primer, the following recipe can be used:
To
manufacture a suitable primer, use the following
recipe: 
8 parts Methyl Ethyl Ketone (MEK)
2 parts Tetrahydrofuran (THF)
Mix thoroughly
Keep lightly covered in metal container
when not in use.
Caution:Carefully
follow manufacturer's guidelines in handling
these products. (Refer to Manufacturer's Material
Safety Data Sheets).
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