A small white plastic tube sits inside every SharkBite push-to-connect fitting. For copper pipe installations, you do not need this plastic insert—but here’s where it gets interesting: you also don’t have to remove it. SharkBite’s official guidance confirms that copper tubing fits over the PEX stiffener easily and holds it against the tube stop without causing connection issues. However, understanding when removal benefits your project can mean the difference between optimal water flow and unnecessary restrictions.
What Is the SharkBite Plastic Insert?
The plastic insert—officially called a PEX stiffener or tube support liner—serves a specific mechanical purpose inside SharkBite fittings. Think of it as internal scaffolding: it reinforces soft, flexible tubing from collapsing when the fitting’s stainless-steel teeth grip down.
How the Insert Functions
Every SharkBite universal fitting arrives with this integral component preloaded. When flexible pipes like PEX, PE-RT, or HDPE enter the fitting, the insert supports the inner wall, ensuring the O-ring seals correctly on the outside of the pipe. Without this backbone, flexible tubing can deform under the gripping force, leading to leaks or reduced water pressure.
| Pipe Material | Insert Required? | Reason |
|---|---|---|
| PEX | Yes | Prevents deformation and ensures tight seal |
| PE-RT | Yes | Similar flexibility to PEX; needs internal support |
| HDPE | Yes | Flexible material requires reinforcement |
| Copper | No | Rigid metal maintains shape under pressure |
| CPVC | No | Hard plastic doesn’t collapse |
Should You Remove It for Copper Pipe?
The short answer: removal is optional but beneficial for copper installations. SharkBite confirms that copper tubing fits over the insert without issues, and the connection remains secure. However, removing it for rigid pipes like copper eliminates any potential flow restriction and ensures the cleanest possible seal.
Arguments for Leaving It In
SharkBite’s official installation documentation states the tube liner is not required for use with CPVC and copper tubing; however, these pipe types “fit over the PEX Stiffener easily and hold it against the tube stop.” The fitting functions correctly either way. For quick repairs or situations where you’re unsure about mixed pipe materials, leaving the insert in place poses minimal risk.
Arguments for Removing It
Plumbing professionals often recommend removal for copper and CPVC because these rigid materials don’t need internal support. Removing the insert can create an uneven seal or prevent the fitting from sliding on properly in some cases. The insert also creates a slight reduction in the inner diameter, though this reduction is generally negligible for most residential applications.
Step-by-Step: How to Remove the Plastic Insert
Removing the tube liner takes only seconds when done correctly. SharkBite fittings allow easy extraction using basic tools.
| Step | Action | Tool Needed | Important Note |
|---|---|---|---|
| 1 | Identify your pipe type | Visual inspection | Confirm it’s rigid copper or CPVC |
| 2 | Insert a pick or pliers | Needle-nose pliers or small pick | Gently grip the liner edge |
| 3 | Pull straight out | Firm, steady pressure | Avoid bending the O-ring seat |
| 4 | Inspect the fitting | Look inside for damage | Check for scratches or distortion |
The SharkBite Disconnect Clip or Disconnect Tongs (sold separately) can also assist in removing the tube liner by pulling it past the O-ring.
Critical Installation Tips for Copper Pipe
Whether you remove the insert or leave it, proper installation technique matters far more than this single component. Preparation prevents leaks—not the presence or absence of the liner.
Deburring Is Non-Negotiable
Use fine sandpaper like 180 grit to remove any old solder or burrs from copper pipe. A SharkBite Deburr & Gauge Tool works perfectly for smoothing edges and measuring insertion depth. Failing to deburr properly remains a leading cause of fitting failure.
Mark the Insertion Depth
Every SharkBite fitting requires the pipe to reach the internal tube stop for a secure connection. Use the gauge tool to measure and mark the proper depth on your pipe with a permanent marker. This simple step is crucial to avoiding leaks.
Push Firmly Until Marked Depth
Insert the pipe through the release collar, then push firmly—adding a slight twisting action—until the pipe reaches the tube stop. Verify that your depth mark aligns with the end of the release collar within 0.005 inches.
SharkBite Max: The No-Liner Solution
SharkBite’s newer Max fittings eliminate this entire question. These redesigned fittings don’t require a PEX tube liner at all, making installations simpler—especially when working on copper and CPVC. The internal geometry has been reengineered to work universally across all compatible pipe types without separate liners.
Key Takeaways
- The plastic insert is optional for copper pipe—SharkBite confirms removal is not necessary, but the fitting works fine with or without it
- Remove the insert for the cleanest seal on rigid pipes like copper and CPVC to eliminate potential flow restrictions
- Always keep the insert for flexible pipes like PEX, PE-RT, and HDPE to prevent collapse and ensure proper O-ring sealing
- Proper pipe preparation—clean cuts, deburring, and correct insertion depth—matters more than whether you remove the liner
- SharkBite Max fittings eliminate the insert entirely, offering a universal solution for all pipe types
Frequently Asked Questions (FAQ)
Can I leave the SharkBite plastic insert in when connecting copper pipe?
Yes, copper pipe fits over the insert and holds it against the tube stop without affecting the connection’s integrity. SharkBite officially states removal is not necessary for copper or CPVC applications.
What happens if I remove the insert from a PEX pipe connection?
Removing the insert from PEX tubing can cause the pipe to collapse under the fitting’s grip, leading to poor sealing, reduced water pressure, and potential failure under heat or pressure cycles.
How do I remove the plastic liner from a SharkBite fitting?
Use needle-nose pliers or a small pick to gently grip the liner’s edge and pull it straight out. SharkBite’s Disconnect Clip or Disconnect Tongs can also assist with removal.
Does leaving the insert in copper pipe restrict water flow?
The insert creates a slight reduction in inner diameter, but this restriction is extremely negligible for most residential plumbing applications. Flow impact is minimal in properly sized systems.
Are SharkBite fittings reusable after removing the insert?
Yes, SharkBite fittings can be reused for testing purposes, though fittings used repeatedly should not become permanent installations. Always inspect the O-ring and gripping teeth before reusing any fitting.
Do SharkBite Max fittings require a plastic insert for copper?
No—SharkBite Max fittings feature a redesigned internal structure that eliminates the need for a PEX tube liner entirely, simplifying installations on copper, CPVC, and other compatible pipe types.
What causes SharkBite fittings to leak on copper pipe?
Common causes include improper deburring, pipe not fully inserted to the tube stop, pipe not cut squarely, or scratches and debris on the pipe’s exterior preventing proper O-ring sealing.
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