What is Solvent Welding?
Solvent weld or solvent welding is a way of joining two pieces of plastic waste pipes using a glue which is called solvent weld cement.
The cement is liberally applied to both parts of the connection and the solvent literally welds the parts together.
Solvent weld is not considered to be the DIY way of doing things but we disagree strongly.
What About Push Fit Fittings?
Push fit fittings and compression fittings are big, bulky and ugly and although they have their place and are sometimes invaluable, solvent weld is much easier, much more reliable, much neater and much cheaper.
Plan Your Pipework Before Solvent Welding it Together
When attempting to solvent weld your waste pipes it is always a good idea to set out the "run" using dry joints and only cement them when you are sure you have it right.
The image above shows all of the parts you might use in a typical installation. The section and images below show you how to join it all together.
Plastic Pipework That can be Solvent Welded
The list below indicates each item in the image above (the labels run in a clockwork direction starting from the pot of solvent weld):
- A – Solvent cement. This usually comes in a 250ml tub and has a application brush in the top. In most cases solvent weld will set in about 10 minutes (will be pretty much solid after 1 minute) and fully cured within 24 hours, but this may vary depending on manufacturer so please read their guidelines. Additionally, it is always a good idea to clean all curfaces to be welded with a suitable degreasing cleaner and also ensure that they clean and free of dirt and dust
- B – Pipe clips. Plastic waste pipes can sag a little as they get hot and it is important that any near horizontal runs are clipped every 500mm or so. If a pipe sags, it stores water and slows up the run. If the run slows a blockage can easily occur
- C – Air admittance valve. More can be found out about this fitting in our project called gurgling sinks, baths, basins and showers
- D – Pipe reducer. Slotted into a 40mm pipe allows a 32mm pipe to be connected to it in line
- E – 90 degree quick bend. Bends in waste pipes are either quick bends or easy bends. A quick bend turns in a short distance and the easy bend takes longer. An easy bend is shown on the right
- F – Equal Tee piece. All openings are of an equal size. Tee pieces cab be bought which allow 32mm waste pipe to join 40mm and 50mm waste pipe and vice-versa
- G – Straight coupling. This is used for connection two lengths of waste pipe in a straight line.
- H – 135 degree bend to gradually turn a pipe run
- I – Short length of 32mm waste pipe
- J and K – Show how to join an access plug to a waste pipe system. If a run of pipe changes direction quickly via a Tee piece or a quick bend a blockage can occur. If you can insert an access plug into the run you will be able to clear any blockages quickly and easily. See our project on fitting waste traps you will find the access plugs in part two of this project
Cutting and connecting waste pipes could not be easier with solvent weld. Simply cut the pipe to length with a hacksaw, apply the adhesive, twist the two parts slightly as you push them together and it is done. Permanent and watertight.
All project content written and produced by Mike Edwards