PVCu solvent cement welding offers a simple and quick means of constructing high integrity leak-free joints. Correctly made joints are stronger than both the pipe and fitting.
The solvent cement operates by chemically softening the outside of the pipe and inside of the fitting. PVCu pressure pipes and fittings are designed for an interference fit.
Although PVCu solvent cement has good gap filling properties, no attempt should be made to increase the clearance between pipes and fittings by excessive abrading.
Joint integrity is greatly reduced if these surfaces are not absolutely clean and properly prepared. The procedure detailed below must be followed.
Please note, under no circumstances should sealing paste be used as this can be harmful to PVCu products.
Prepare the fittings and pipe as follows:
1. Cut the pipe at right angles to its axis and to the required length. Deburr the cut end of the pipe and then chamfer the leading edge of the pipe at approximately 30° – 40°. This will prevent the solvent cement being wiped from both the pipe and the fitting when pushed together.
2. Dry fit the pipe to the socket of the fittings. When the pipe is fully home in the socket, draw a line around the pipe at the edge of the socket. Where this is not possible, measure the socket depth and draw a line at the corresponding point along the pipe. This will give a visual indication to ensure that the pipe is fully home in the socket.
3. Roughen both the pipe surface up to the indicator mark and the inside of the socket with emery cloth, this will take off the shiny surface.
4. Do not roughen both surfaces of the pipe and fitting to the extent that the clearance between them is noticeably increased.
5. Degrease the surface of both the pipe and the fitting with a lint free cloth or piece of absorbent paper dampened with Effast MEK Cleaner. Ensure that both jointing surfaces are fully cleaned. Allow the cleaner to evaporate, before applying the solvent cement. Any excess cleaner should be quickly removed from the surface of the pipe or fitting as this may affect the integrity of the system.
6. Select the correct solvent cement. Do not attempt to solvent weld PVCu pipe and fittings with ABS cement or vice versa. ABS cement, will need to be thoroughly stirred before use, PVCu cement does not.
7. Apply the solvent cement straight from the tin with a suitably sized brush. Ensure that the roughened area in the socket and pipe up to the visual indicator is completely covered with an even layer of cement. It is essential that the excessive use of solvent cement is avoided. This part of the procedure must be done quickly and neatly as the solvent cement must still be wet when the pipe and fitting is pushed together.
8. Push the pipe and fittings together and hold in place for up to 30 seconds for smaller diameter sizes (up to 2"/63mm) and up to 1 minute for larger sizes (2"/63mm – 12"/315mm). When the joint is made a bead of cement will form between the chamfer of the pipe and the central register of the fitting. This bead will help ensure the integrity of the seal. Excessive deposits inside the fittings must be avoided as this can weaken the wall especially on small sizes. A bead of solvent cement will also form around the outer joint of the pipe and socket. This excess cement should be wiped away leaving the outer part of the joint clean. Do not disturb the joint for 10 – 15 minutes.
9. After 8 hours under normal conditions the cement within the joint will have dried enough to be able to withstand the rated pressure of the pipe system, however, we would recommend leaving the joint for the full period of 24 hours wherever possible. Please note that all drying times in a pipe system only start on the completion of the last joint. After 24 hours the pipe system can be fully pressure tested. The test pressure should be equal to 1½ times the rated pressure of the lowest rated fitting or pipe within the system.
10. Please note that during the jointing procedure both solvent cements and cleaners produce vapours (fumes), therefore, we recommend that the jointing procedure should be undertaken in a well-ventilated area. We also recommend ventilation within the pipe system during assembly, to disperse any potentially harmful vapours.
The above jointing procedure is given as a guide, for further details please refer to our technical guide, which is available upon request.
Connect joints in wet or damp conditions.
Use dirty brushes or cleaning rags which are dirty or oily.
Use the same brush for different solvent cements.
Dilute or thin solvent cements with MEK cleaner.
Leave solvent cement tins open.
Use near a naked flame, or smoke whilst jointing.
Make joints in a confined space.
An extensive range of threaded fittings are available mostly having parallel threads to relevant standards. Tightening of threads should only be done by hand or at most by an extra quarter turn with a strap wrench.
Extra care must be taken not to over tighten or damage the fitting component. Pipe wrenches must not be used in any circumstances.
It is recommended that PTFE tape should be used in the jointing of threaded fittings to complete a satisfactory seal.
Please note, under no circumstances should a sealing paste be used as this can damage both PVC and ABS products.
If you require any further information then don’t hesitate to ring us here at Pipestock on 0845 634 1053. We’re always happy to help!