A.O. Smith Power Direct ventedGasModels Instruction Manual page 21

prIMer
It is recommended that Tetrahydrofuran (THF) be used to prepare the
surfaces of pipe and fittings for solvent welding. Do not use water,
rags, gasoline or any other substitutes for cleaning PVC, ABS or
CPVC surfaces. A chemical cleaner such as MEK may be used.
ceMent
The cement should be a bodied cement of approximately 500 to
1600 centipoise viscosity containing 10-20% (by weight) virgin PVC
material solvated with tetrahydrofuran (THF). Small quantities of
dimethyl formamide (DMF) may be included to act as a retarding
agent to extend curing time. Select the proper cement; Schedule 40
cement should be used for Schedule 40 pipe. Never use all-purpose
cements, commercial glues and adhesives or ABS cement to join
PVC or CPVC pipe and fittings.
applIcators
Select a suitable pure bristle type paint brush. Use a proper width
brush or roller to apply the primer and cement (see chart below).
Speedy application of cement is important due to its fast drying
characteristics.
recoMMended Brush* sIZe for prIMer
and ceMent applIcatIons
nominal pipe (Ips)
3
*use onlY natural BrIstle
3. MaKInG the joInt
a. cutting
Pipe must be squarely cut to allow for the proper interfacing of the
pipe end and the fitting socket bottom. This can be accomplished
with a miter box saw or wheel type cutter. Wheel type cutters are
not generally recommended for larger diameters since they tend
to flare the corner of the pipe end. If this type of cutter is used,
the flare on the end must be completely removed.
NOTE: Power saws should be specifically designed to cut plastic
pipe.
size Brush width (Ins.)
1-1/2 – 2-1/2
B. deburring
Use a knife, plastic pipe deburring tool, or file to remove burrs
from the end of small diameter pipe. Be sure to remove all burrs
from around the inside as well as the outside of the pipe. A slight
chamfer (bevel) of about 10°-15° should be added to the end
to permit easier insertion of the pipe into the end of the fitting.
Failure to chamfer the edge of the pipe may remove cement from
the fitting socket, causing the joint to leak.
C. Test dry fit of the joint
Tapered fitting sockets are designed so that an interfaced fit
should occur when the pipe is inserted about 1/3 to 2/3 of the
way into the socket. Occasionally, when pipe fitting dimensions
are at the tolerance extremes, it will be possible to fully insert
dry pipe to the bottom of the fitting socket. When this happens,
a sufficient quantity of cement must be applied to the joint to fill
the gap between the pipe and fitting. The gap must be filled to
obtain a strong, leak-free joint.
d. Inspection, cleaning, priming
Visually inspect the inside of the pipe and fitting sockets and
remove all dirt, grease or moisture with a clean dry rag. If wiping
fails to clean the surfaces, a chemical cleaner must be used.
Check for possible damage such as splits or cracks and replace
if necessary.
depth-of-entry
Marking the depth of entry is a way to check if the pipe has
reached the bottom of the fitting socket in Step F. Measure
the fitting depth and mark this distance on the pipe O.D. You
may want to add several inches to the distance and make a
second mark as the primer and cement will most likely destroy
your first one.
21
step a
step B