20
VENT PIPE PREPARATION
1.
INITIAL PREPARATION
A.
Make sure the solvent cement you are planning to use is
designed for the specific 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 qualifications or those of your contractor.
The solvent welding technique of joining PVC and CPVC pipe
is a specialized skill just as any other pipe fitting technique.
E.
Closely supervise the installation and inspect the finished
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 fittings 6 inches
(15.2 cm) and above.
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 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. 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 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.
STEP A
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