If you are planning a plumbing project, learning how to use PEX pipe
fittings is an essential skill. PEX (cross-linked polyethylene) tubing has
revolutionized the plumbing industry because it is flexible, resistant to scale
and chlorine, and easier to install than rigid copper or CPVC pipes.
Whether you are a DIY enthusiast or a professional plumber, understanding
the correct way to use PEX fittings ensures a leak-free system that lasts for
decades.
In this guide, we will cover the different types of PEX fittings, the tools
you need, and a step-by-step breakdown of how to make reliable connections.
Why Choose PEX?
Before diving into the "how," it helps to understand the "why." PEX is
popular because:
Flexibility: It can bend around corners, reducing the need for elbow
fittings.
Cost-Effective: It requires fewer fittings and less labor than traditional
piping.
Freeze Resistance: PEX can expand if water freezes inside, reducing the
chance of burst pipes.
Types of PEX Fitting Systems
There are three primary methods for connecting PEX pipe. Your choice
depends on the tools you own and local building codes.
1. Crimp/Cinch Systems
This method uses a copper crimp ring or a stainless steel cinch clamp to
secure the fitting to the pipe. It is the most popular choice for DIYers because
the tools are affordable.
2. Push-to-Connect
These fittings allow you to push the pipe directly into the fitting without
any special tools. They are excellent for tight spaces and quick repairs, though
they are more expensive per fitting.
3. Expansion Systems
This system expands the PEX pipe and fitting so the pipe shrinks back over
the fitting, creating a tight seal. It requires a specialized expansion tool and
is usually preferred by professionals.
Tools You Will Need
To get started with the crimp method (which we will focus on), gather the
following:
PEX Tubing: Ensure it is the same size as your fittings.
PEX Fittings: Brass or poly-alloy fittings.
Copper Crimp Rings: The correct size for your pipe.
Crimp Tool: A go/no-go gauge is often built into quality tools.
Pipe Cutter: For a clean, square cut.
Stainless Steel Cinch Clamps (alternative to crimp rings).
Step-by-Step: How to Use PEX Crimp Fittings
Follow these steps carefully to ensure a watertight connection.
Step 1: Cut the Pipe
Use a dedicated PEX pipe cutter. It is vital to make a straight, 90-degree
cut. If the cut is angled, the pipe will not seat fully into the fitting, which
can cause leaks. Look at the end of the pipe—if it is oval or ragged, cut it
again.
Step 2: Slide the Ring Onto the Pipe
Choose the correct size crimp ring (ensure it fits snugly around the pipe).
Slide it onto the pipe so it is at least 1/4 inch from the end. Do not put it on
the end yet; it needs to be out of the way so you can insert the fitting.
Step 3: Insert the Fitting
Push the barbed PEX fitting into the end of the pipe. Use a twisting motion
while pushing to help it slide in. Push it until the pipe meets the shoulder of
the fitting. You cannot push it in too far; but you can push it in too little.
Make sure the pipe end is not visible past the crimp ring placement.
Step 4: Position the Crimp Ring
Slide the copper ring back down the pipe so it sits over the barbs of the
fitting. It should be positioned 1/4 inch to 1/8 inch from the end of the pipe.
It needs to cover the barbs but not hang off the edge.
Step 5: Crimp the Ring
Place the crimp tool over the ring. Squeeze the handles firmly until they
stop. Do not crimp the same ring twice if you are using copper rings, as this
can weaken the metal. If you are using cinch clamps, use the cinch tool to
tighten the clamp until it clicks or feels snug, then use the tool to ratchet it
tighter.
Step 6: Inspect the Connection
This is the most important step. Use a go/no-go gauge (often built into the
crimp tool or sold separately).
Place the "GO" side over the crimped ring. If it slides over easily, the
crimp is too loose.
Place the "NO-GO" side over the ring. If it fits over the ring, the crimp
is too tight or the ring is damaged.
The ring must pass the "GO" side but fail the "NO-GO" side. If it fails
this test, you must cut the pipe and start over with a new fitting and ring.
How to Use Push-to-Connect Fittings
If you are using push-to-connect (SharkBite) fittings, the process is even
simpler:
Cut the pipe square and clean the end.
Use a deburring tool to remove any rough edges.
Mark the depth of the fitting on the pipe with a marker.
Push the fitting onto the pipe until the marker reaches the fitting's
edge.
Pull back gently to ensure the stainless steel teeth have locked onto the
pipe.
Common Mistakes to Avoid
Using the Wrong Size Ring: A 3/4" ring will not seal a 1/2" pipe.
Forgetting the Ring: It sounds silly, but it happens often. Always check
you have the ring on before inserting the fitting.
Poor Cuts: An angled cut will lead to gaps.
Skipping the Gauge Check: Even with the best tool, sometimes a crimp fails.
Always check.
Conclusion
Learning how to use PEX pipe fittings is a valuable skill that can save you
money on home repairs and renovations. The crimp method offers reliability and
low cost, while push-to-connect offers speed and ease. Always follow local
plumbing codes and test your system with air or water pressure before closing up
walls.
By following these steps and using the right tools, you can create a
durable plumbing system that will provide years of trouble-free service.
