Introduction
SharkBite fittings are the go-to connectors for DIYers and professionals who want fast, leak-free plumbing without soldering or clamping. But one tiny detail often sparks confusion — the plastic insert (also called the tube liner) inside the fitting.
This small plastic piece can make or break your connection depending on what type of pipe you’re joining. Remove it at the wrong time, and you risk leaks. Leave it in when you shouldn’t, and you could restrict water flow or damage the fitting.
Let’s break down when — and when not — to remove that insert, using clear, real-world logic.
Understanding the Plastic Insert
What the Insert Does
The plastic insert supports the inner wall of softer tubing, such as PEX, to prevent it from collapsing under the gripping force of the SharkBite’s stainless-steel teeth.
Think of it like a backbone: rigid, subtle, but essential to keeping the structure sound.
Where It’s Found
Every SharkBite push-to-connect fitting comes preloaded with this insert. You’ll notice it as a small white (or translucent) tube inside the brass opening.
| Pipe Type | Insert Needed? | Reason |
|---|---|---|
| PEX (Cross-linked Polyethylene) | Yes | Prevents pipe deformation and ensures a tight seal. |
| CPVC (Chlorinated Polyvinyl Chloride) | No | Pipe is rigid enough; insert can cause restriction. |
| Copper | No | Metal walls maintain their shape under pressure. |
| PE-RT (Polyethylene of Raised Temperature) | Yes | Similar flexibility to PEX; needs support. |
When To Remove The Plastic Insert
1. When Connecting to Copper or CPVC Pipes
Remove the plastic tube liner when connecting to copper or CPVC. These pipes are rigid and don’t collapse under pressure. Leaving the insert inside can create an uneven seal or even prevent the fitting from sliding on properly.
Key Tip:
Use a debur tool or fine sandpaper to smooth out the pipe edge before pushing it into the fitting. A clean edge ensures a perfect grip.
When To Leave The Plastic Insert In
1. When Connecting to PEX or PE-RT
Keep the insert in place when using PEX or PE-RT. These flexible materials can bend or compress slightly under tension. The insert prevents the teeth from biting too deep and maintains the internal diameter for steady water flow.
If you remove it, you risk:
- Minor leaks from improper compression
- Reduced water pressure
- Long-term damage under high temperature cycles
2. For Temporary or Mixed Connections
If you’re unsure which material you’re joining (for example, in an older remodel with mixed pipes), leave the insert in until you can confirm. It’s better to have slight restriction than a full leak.
How To Remove The Insert Correctly
| Step | Action | Tool | Note |
|---|---|---|---|
| 1 | Check pipe type | Visual inspection | Confirm if it’s rigid (CPVC/Copper) or flexible (PEX/PE-RT). |
| 2 | Use a pick or needle-nose pliers | Insert tool into liner edge | Gently twist — do not gouge the brass. |
| 3 | Pull straight out | Firm but gentle pressure | Avoid bending the fitting’s O-ring seat. |
| 4 | Inspect for damage | Look inside fitting | Any scratches or distortion? Replace the fitting. |
Benefits of Knowing When To Remove the Insert
- Leak prevention: Right choice equals long-term reliability.
- Full flow efficiency: Avoid pressure drops caused by internal obstructions.
- Reduced maintenance: Proper fits mean fewer callbacks and repairs.
- Extended fitting life: Prevents premature O-ring wear.
Risks of Getting It Wrong
| Mistake | Result |
|---|---|
| Leaving insert in copper line | Restricted flow, poor seal, possible leaks. |
| Removing insert from PEX line | Pipe collapse, reduced pressure, failure under heat. |
| Forcing fitting with insert on rigid pipe | Deformed O-ring or cracked fitting. |
In plumbing, small details carry big consequences. Treat the insert like a safety pin — handy only when used in the right place.
Conclusion
The rule of thumb is simple:
Keep the plastic insert for flexible pipes (PEX, PE-RT). Remove it for rigid ones (Copper, CPVC).
Following this one guideline ensures secure connections, consistent pressure, and leak-free performance across your plumbing system.
Key Takeaways
- Always identify your pipe type before inserting a SharkBite fitting.
- PEX and PE-RT need the insert; Copper and CPVC don’t.
- A smooth pipe edge and correct depth mark are crucial for sealing.
- For uncertain cases, err on the side of leaving the insert in until confirmed.
- Proper handling extends both fitting life and water system efficiency.
Frequently Asked Questions (FAQ)
1. When should I remove the plastic insert from a SharkBite fitting?
Remove it only when connecting to copper or CPVC pipes, since they’re rigid enough to hold shape without internal support.
2. Can I leave the insert in for copper pipes?
You can, but it’s not recommended. It may slightly restrict water flow or prevent a full seal, increasing leak risk.
3. What happens if I remove the insert from a PEX pipe?
The PEX may collapse, leading to poor sealing, reduced water pressure, and eventual failure under heat or pressure.
4. Are SharkBite fittings reusable after removing the insert?
Yes, as long as the O-ring and gripping teeth are undamaged. Always inspect the fitting before reuse.
5. Do I need special tools to remove the insert?
No — needle-nose pliers or a small pick work fine. Avoid sharp tools that might scratch the fitting’s inner surface.
6. How can I tell if the insert is missing or damaged?
Look inside the fitting; you should see a smooth, white plastic ring. If it’s jagged, bent, or missing, replace it before use.
7. Can I buy replacement inserts separately?
Yes. SharkBite sells insert kits compatible with most fitting sizes. Always match them to your pipe type and diameter.
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