How to cut and crimp PEX pipe (AVOID Doing This!)

PEX has become more popular in the past few years. It is a cheap and easy-to-use material. Steel and copper were harder to handle. Plumbers are able to work more efficiently with PEX. DIY’ers can install their own plumbing as well given that PEX is quite straightforward to work with. Let’s take a look at how PEX is cut and crimped. 

PEX is a great material to use as you can install it quickly and it is quite affordable.

How to cut PEX

PEX can have a plastic mantle (or outer plastic shell). We can use a pocket knife to remove this. Be careful that you don’t damage the water pipe itself when you do this. Just cut deep enough and go around the mantle. This should allow you to remove it without too many issues.

 Once this is done, we can cut the PEX pipe itself. This is done with a PEX cutting tool. Depending on the diameter of your pipe, you will have to pick the right one. Measure where you have to cut the pipe and draw a line in this spot. This makes it easier to see where you have to cut. Then you slide the PEX cutter over this place. Then you just have to close the tool. Cut in one smooth movement. Make sure that you cut perfectly straight. 

It is important that the water flow doesn’t get interrupted. This is why we will use the calibration tool. This is a piece of plastic that fits inside of the pipe. It allows us to make the pipe round again so that the water doesn’t get slowed down. Just place the correct size inside the pipe. Once this is done, you just turn this piece around a few times until the pipe is perfectly round. Check if there is no damage to the pipe before you install it. Small tears can lead to water leaks and it is best to discard a piece of pipe if you think that there is an issue. This ensures that you don’t have to redo a part of the installation later on. 

Example of a PEX cutter

Once this is done, we can connect the PEX pipe to the rest of the installation. This approach should work for both PEX-A and PEX-B systems. If you make a dent in PEX-A, it can be fixed with a heat gun. If this happens with PEX-B, you will have to cut this piece of pipe and throw it away.

 If you see some dirt around the pipes, you can use a cloth to remove it. Make sure that screws or other building materials don’t get inside the pipes. You can use some tape to close them off when you are working on something else.

How to crimp PEX: clamp vs crimp

Once we have cut the PEX pipe to the right size, we can connect it with another piece of PEX pipe. Let’s take a look at how we can crimp PEX-B.

We start by picking the right fitting (or connector). The diameter has to be right and the angle as well. We slide the plastic ring over the pipe and insert the metal fitting. Make sure that the pipe goes until the wider part of the metal piece. The plastic ring should be between ⅛” and ¼” from the fitting stop. 

 Once this is done, we can use a crimping tool to close the ring. Some tools require less force than others so make sure that you get one that is easy to use. Once it has been done, we have to check if the crimping was done properly.

This is done with a crimp ring gauge (or go/ no go gauge tool). It is just a piece of metal that you can slide over the ring. If it is not possible to get it over the ring, it indicates that the cramping wasn’t successful. You have to check this for every ring that you install to ensure a proper connection. 

Some crimping tools have a cutter that allows you to remove the plastic ring if there is a problem. You can then reuse the fitting and pipe and install another ring. Be careful that you don’t damage the pipe when you do this. 

PEX-B has the fittings inside the pipes. This can restrict the water flow and lead to low pressure in some faucets or the shower. To fix this, you can use a wider pipe diameter. PEX-A doesn’t have this issue as the fittings are not inside of the pipes. This is why a lot of plumbers prefer PEX-A over PEX-B as wider pipes take up more space. 

PEX-A is installed in another way. We use a bigger plastic ring and don’t need metal fittings. An expansion tool makes the fitting wider and we just slide it over the other pipe. The ring will get back to its original size and we will have a strong connection.  

After a while, your crimping tool will have to be calibrated. Some crimping tools also are adjustable and work with different diameters, make sure that you pick the right option when you use them. If you notice that a lot of fittings are installed incorrectly (with the go/ no go gauge tool), then it might be time to check your crimping tool. 

To conclude, we can say that cutting and crimping PEX is quite straightforward. You just need to do it a few times and you will get used to the technique. Getting the right tools is essential as this will make everything easier. If you make a mistake, it is often quite easy to fix.

You can remove the piece of pipe or add another fitting. Make sure that PEX is allowed by your local code. You should also pressure test your installation to make sure that there are no leaks. Make sure that the PEX isn’t exposed to sunlight as this type of material is not able to deal with it. 

Learning to work with PEX can be quite daunting at first. After a few tries, you should notice that it is quite easy to use. Just make sure that you use the right tools for the specific type of PEX that you are working with.

It also takes some discipline to work with PEX as you have to check each connection. One fitting that hasn’t been installed properly, can lead to water leaks behind a wall. This can create a lot of damage.

Before you start using a PEX system, you should test it to make sure that it can handle the water pressure. If it drips just a little, it can already lead to a lot of problems. PEX pipes are hidden behind the drywall and this can make it hard to access without damaging the drywall.

Having to repair drywall is a hassle so it is best to avoid this and test the PEX pipes.

PEX can be a lot of fun to work with if you are used to it. Plumbers can also work very fast with it. In one day they can often install multiple rooms and activate the water. It is important to pressure test the system before it is used.

Make sure to use the right tools when you work with PEX. For example, the cuts have to be made with a special tool so that the material is not damaged. If you notice that your cutter is breaking down, simply get a new one.