State SDV 75 70 NE/PE - Manual (Page 21)

21
PRIMER
It is recommended that Tetrahydrofuran (THF) be used to prepare the
surfaces of pipe and fi ttings 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 fi ttings.
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.
TABLE 3: RECOMMENDED BRUSH* SIZE FOR PRIMER
AND CEMENT APPLICATIONS
Nominal Pipe (IPS) Size Brush Width (INS.)
3 1-1/2 – 2-1/2
*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 fi tting 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 fl are the corner of the pipe end. If this type of cutter is used,
the fl are on the end must be completely removed. NOTE: Power
saws should be specifi cally designed to cut plastic pipe.
STEP A
B. Deburring
Use a knife, plastic pipe deburring tool, or fi le 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 fi tting.
Failure to chamfer the edge of the pipe may remove cement from
the fi tting socket, causing the joint to leak.
STEP B
C. Test dry fi t of the joint
Tapered
fi tting sockets are designed so that an interfaced fi t
should occur when the pipe is inserted about 1/3 to 2/3 of the
way into the socket. Occasionally, when pipe fi tting dimensions
are at the tolerance extremes, it will be possible to fully insert
dry pipe to the bottom of the fi tting socket. When this happens,
a suffi cient quantity of cement must be applied to the joint to fi ll
the gap between the pipe and fi tting. The gap must be fi lled to
obtain a strong, leak-free joint.
D. Inspection, cleaning, priming
Visually inspect the inside of the pipe and fi tting 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 fi tting socket in Step F. Measure the fi tting 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 fi rst one.
Apply primer to the surface of the pipe and fi tting socket with a
natural bristle brush. This process softens and prepares the PVC,
ABS or CPVC for the solvent cementing step. Move quickly and
without hesitation to the cementing procedure while the surfaces
are still wet with primer.
E. Application of solvent cement
• Apply the solvent cement evenly and quickly around the
outside of the pipe at a width a little greater than the depth
of the fi tting socket.
• Apply a light coat of cement evenly around the inside of the
fi tting socket. Avoid puddling.
• Apply a second coat of cement to the pipe end.
STEP E