Waste pipe - solvent weld joints

Solvent weld joints for plastic waste pipes

This type of fitting is far neater than compression as each consists of a section of shaped pipe only slightly larger than the waste pipe itself.

These come in a huge variety of forms, from bends and straight connectors to compression / solvent weld adapters and inspection pieces.

Cutting plastic waste pipe

When cutting pipe, allowance must be made for the additional length required inside the fitting. Insert a piece of pipe until it is fully home and mark the amount to be added. You may find it useful to place a small pencil alignment mark on the fitting and the pipe so that they can be quickly and easily positioned later. This is particularly useful where bends are used.

Cut pipes with a small hacksaw. Use a paper guide to ensure that the cut is square.

Clean up the ends with a small file to remove any dirt trapping burrs.

Welding or glueing the joints

Paint the solvent onto both the outer side of the pipe and the inner side of the fitting. The type of solvent to be used should be as recommended by the manufacturer. Only apply this to the areas of pipe and fitting which will be in contact with each other. The solvent literally melts the plastic. The two pieces may then be slotted together using a slight twisting action at the same time. Be sure to line up the parts quickly. As the solvent dries, the plastic hardens once more and the two surfaces become fused as one.

Check with the instructions as to when it will have cured sufficiently for water to be allowed to flow through. Generally this will be about an hour for cold water and longer for hot water.

If you are assembling a long run of plastic waste, you should fit special expansion joints every 3m or so. Unlike the other systems, there is no allowance for thermal movement with this type. Failure to allow for this may result in stress and possible failure at the joints.

When the pipe is tested, small leaks may be overcome by allowing the pipe to dry out and adding a little solvent to the mouth of the fitting.

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