Do’s and Don’t’s for cementing plastic pipe systems

Do’s and Don’t’s for cementing plastic pipe systems 

·         Do chamfer the edges of a cut pipe. Chamfering is not, as many incorrectly believe, a process that enables the pipe and fitting to glide together more easily, although this can be an added benefit. The main purpose of chamfering the outside edge of a pipe before the application of cement is to allow as much of the cement as possible to enter the joint. A straight cut pipe without any chamfering will act as a blade, scraping off the solvent cement inside the socket.

·         Do use additional unions to make the process pipework easy to disassemble in the future. Although it is often difficult to imagine why a system might need to be taken apart, unions should still be added for good practice. A pipeline may require to be inspected, cleaned or modified, and if unions are installed then these processes become easier, reducing downtime in the future.

·         Although not always possible, do try to leave a short section of pipe between each fitting rather than butting them up right next to each other. A section of plastic pipe between the fittings should be a little longer then a socket depth for that size of pipe. Following this rule allows far easier adaptation of the pipework in the future, as a fitting can be cut out, leaving a spigot long enough to cement another one on.

·         Do work out where your last join will be about five or six joins before you get to it, and ensure there will be enough movement available to make the joint. It is often the case that inexperienced fitters get to the last join and realise it is to a wall connection or other immovable object, and there is not sufficient space to allow for the socket to be pushed on to the pipe. In such situations a remedy is to fit a short section of plastic pipe, with a union at either end, so that it can be removed to give movement to the plastic pipe system.

·         Don’t add cleaner to your cement to try to thin it down after leaving the led off for an extended period. This will result in a poorly performing and potentially leaking, joint. Whenever possible rest the lid of the cement tin back on top to prevent evaporation of the solvent. If the solvent cement becomes too thick to apply or lumpy, it should be discarded and a new tin opened.

Finally, remember that shortcuts taken when assembling plastic pipe system always bite back in the end!