Some thermo plastic pipes such as pvc pipe, cpvc pipe, and abs pipe are connected together using a solvent weld technique, where a glue is applied to both the pipe and fitting. When pushed together in a socket / spigot arrangement, the glue melts the outer layers of plastic from the pipe and socket so they then melt together and dry, forming a complete seal.
The process of joining pvc and abs pipe together seems, at first hand, a simple one. It is however full of small technicalities that once mastered, can save a lot of time and money.
Common errors are as follows:
Putting the pvc or abs solvent cement on the pipe (or spigot) first. In almost all cases, the plastic pipe glue should be applied to the socket first, as this can then be put down, the pipe glued, and then the fitting picked back up and pushed onto the pipe. If this is done the other way round, the pipe / spigot, when covered in glue, cannot be laid down anywhere.
Gluing valves – When a valve is glued you must be very careful not to let glue run down into the valve body or the mechanism may seize. Apply the glue to one side of the valve, sit the valve vertically, with the glued part of the pvc or abs valve at the bottom and then apply the glue to the pipe. Push the valve, downwards onto the pipe and leave to set in this position. If there is any doubt that some glue may have entered the body of the fitting, turn the handle a few times to ensure the vale stays free. With abs pipe systems this has to be done very quickly as abs sets much faster than pvc.
Twisting the pipe – Many inexperienced users of Plastic Pipe Fittings believe that twisting the pipe, as it enters the socket, will result in the glue being more evenly smeared around the joint in the fitting. This is incorrect; rotational force applied to the plastic pipe and fitting as they are being joined results in the glue becoming denser in some places and void in others. It is acceptable to apply a small amount of rotational movement to the pipe, one it is fully home in the socket, to align it correctly. This movement should be less than 10 degrees and should take place immediately that the pipe has been pushed home. Once again, with abs pipe and fittings, there is very little time for any movement as the solvent welding process is so quick.
Sharp edges on the pipe – Trying to glue a freshly cut piece of plastic pipeinto a fitting is a recipe for disaster. The sharp, cut edge of the pipe, will scrape away the glue in the plastic fittings and any swarf remaining on the pipe end may get drawn into the joint and result in a void. To combat this, all swarf must be removed, the pipe chamfered on the outside edge to an angle of approximately 45 degrees and then cleaned of any debris.
Following these simple tips will save a huge amount of time and anguish when working with pvc, abs and c-pvc pipe and fittings.
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