21
VENT PIPE PREPARATION
1.
INITIAL PREPARATION
A. Make sure the solvent cement you are planning to use is
designed for the specifi c application you are attempting.
B.
Know the physical and chemical characteristics and limitations
of the PVC and CPVC piping materials that you are about to
use.
C.
Know the reputation of your manufacturer and their products.
D.
Know your own qualifi cations or those of your contractor. The
solvent welding technique of joining PVC and CPVC pipe is a
specialized skill just as any other pipe fi tting technique.
E.
Closely supervise the installation and inspect the fi nished
job before start-up.
F.
Contact the manufacturer, supplier, or competent consulting
agency if you have any questions about the application or
installation of PVC and CPVC pipe.
G.
Take the time and effort to do a professional job. Shortcuts will
only cause you problems and delays in start-up. By far, the
majority of failures in PVC and CPVC systems are the result of
shortcuts and/or improper joining techniques.
2.
SELECTION OF MATERIALS
• Cutting Device - Saw or Pipe Cutter
• Deburring Tool, Knife, File, or Beveling Machine (2” and above)
• Brush - Pure Bristle
• Rag - Cotton (Not Synthetic)
• Primer and Cleaner
• Solvent Cement - PVC for PVC Components and CPVC for CPVC
Components
• Containers - Metal or Glass to hold Primer and Cement. Select
the type of PVC or CPVC materials to be used on the basis of their
application with respect to chemical resistance, pressure rating,
temperature characteristics, etc.
• Insertion Tool - Helpful for larger diameter pipe and fi ttings 6 inches
(15.2 cm) and above.
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 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.
IMPORTANT NOTE: A dauber type applicator should only be used on
pipe sizes 2” and below. For larger diameter pipe, a brush or roller must
be used.
RECOMMENDED BRUSH* SIZE FOR PRIMER
AND CEMENT APPLICATIONS
Nominal Pipe
Size Brush Width
(IPS)
(INS.)
2
1-1/2
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
