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" 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.
SAFETY PRECAUTION: PRIMERS AND CEMENTS ARE EXTREMELY FLAMMABLE, AND MUST NOT BE STORED OR USED NEAR HEAT OR OPEN FLAME. ALSO, USE ONLY IN A WELL-VENTILATED AREA.
APPLICATORS
Select a suitable pure bristle type paint brush. Use a proper width brush or roller to apply the primer and cement . 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.
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.
STEP A
NOTE: Power saws should be specifically designed to cut plastic pipe.
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.
STEP B
C. Test dry fit of the joint
Tapered fitting sockets are designed so that an interference 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.
