PEX Expansion Fittings: Why Uponor ProPEX Is Best

What Are PEX Expansion Fittings and How Do They Work?

PEX expansion fittings are traditionally used with PEX-A tubing, the most flexible type of cross-linked polyethylene pipe. Instead of relying on metal crimp rings or clamps, expansion fittings use the natural "memory" of PEX-A to form a watertight seal.

Here's the process in action:

1. Expand the pipe: Using a specialized PEX expansion tool, the end of the PEX-A pipe is carefully expanded.
2. Insert the fitting: A plastic or brass expansion fitting is pushed into the enlarged pipe while it is still expanded.
3. Pipe contracts around the fitting: As the PEX-A pipe returns to its original size, it grips the fitting tightly, forming a strong, watertight joint that strengthens over time.

Because the pipe itself grips the fitting, rather than being squeezed by an external clamp, expansion connections are less likely to loosen or leak, more resistant to stress cracking, and able to maintain full-bore water flow without narrowing at the joint.

This makes expansion fittings especially valuable in homes where water pressure, durability, and long-term peace of mind are top priorities.

There is a wide variety of PEX connectors that are used depending on the type of PEX tubing or the particular brand. If you want to know more, you can read our article on the different types of PEX connectors.

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How Long Do PEX Expansion Fittings Last?

One of the main reasons homeowners choose PEX expansion fittings is their impressive longevity. When installed correctly, they can last 50 years or more, which is on par with the best copper pipes but with fewer concerns about corrosion or mineral build-up.

The fittings themselves are usually made from high-quality brass or engineered polymer, both of which are resistant to wear, chemical damage, and temperature stress. Because the pipe contracts tightly around the joint, the seal only becomes more secure over time.

Expansion fittings are also ideal for climates with freeze-thaw cycles. Unlike rigid pipes that can crack under freezing conditions, PEX-A can expand slightly and then return to its original shape. The expansion connection maintains its seal even if the pipe experiences temperature-related stress, reducing the likelihood of burst pipes in colder regions.

For homeowners looking for a long-lasting plumbing solution, expansion fittings are one of the most reliable options on the market today.

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Are PEX Expansion Fittings Better Than PEX Crimp or Clamp Fittings?

Both expansion fittings and crimp/clamp fittings are designed to connect PEX tubing, but they perform very differently when compared side by side. The key difference lies in how the seal is formed and how that seal holds up over decades of use.

Crimp and Clamp Fittings

Crimp and clamp fittings work by compressing a copper or stainless-steel ring around the PEX pipe. This ring holds the pipe against the fitting, creating a seal that depends on the ring's ability to maintain its grip over time.

While effective in the short term, these joints can weaken with age due to water chemistry, temperature fluctuations, or physical stress.

Another drawback is that the ring and fitting slightly reduce the inside diameter of the pipe, which can restrict water flow. Crimp and clamp fittings are usually quicker to install for small repairs and are often chosen for budget-friendly or DIY plumbing projects.

Expansion Fittings

Expansion fittings take a very different approach. Using the natural shape memory of PEX-A, the pipe is expanded with a specialized tool, the fitting is inserted, and then the pipe contracts tightly around it.

This creates a joint that actually strengthens over time as the pipe continues to grip the fitting. Because no ring or clamp is constricting the pipe, the full-bore waterway is preserved, ensuring better pressure and water flow throughout the system.

The real deciding factor between the two systems is longevity. While crimp and clamp fittings can serve reliably in the short term, their reliance on a metal ring makes them more vulnerable to wear and tear decades down the line.

Expansion fittings, by contrast, are built for long-term performance, consistently outlasting crimp and clamp connections while offering homeowners peace of mind that their plumbing system will remain secure for decades.

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Should I Repipe Using PEX Expansion Fittings?

If you're considering a full home repipe, Uponor PEX-A ProPEX expansion fittings are one of the most reliable choices available today.

The system offers long-lasting durability, consistent water flow, and a connection method that actually strengthens over time. Unlike crimp or clamp fittings, expansion fittings are designed to hold up for decades with minimal risk of leaks or failures.

Contact one of our local repipe consultants today for a free, fixed-price quote and discover how easy it can be to upgrade your home with PEX expansion fittings.

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Get a Quote for Repiping Your Home With PEX Pipes

Here at Repipe Specialists, we've fully replaced the plumbing in over 75,000 homes since 1991. Using Uponor PEX-A expansion fittings not only ensures long-lasting performance but can also save you money over time. All of our repipes are backed by a lifetime warranty, giving homeowners peace of mind and financial protection.

• Speed: Our repipe crews typically complete a repipe in a day, returning on another day for wall patching.
• Convenience: Through our One-Stop Repipe™ Process, we handle everything from permits, to wall patching, to inspections.
• Cleanliness: Our crews are trained to protect your home while working (we cover all surfaces with protective sheeting), and to clean up fully at the end of each day.
• Peace of Mind: Repipe Specialists is a fully licensed plumber in every state we operate in, and we back all of our repipes with a lifetime warranty.
• Financing Programs: To help take the sting out of unplanned repipe expenses, we offer several financing programs.
• Price: As a specialist that performs hundreds of repipes a week, we can deliver high-quality repipes at a lower cost vs generalist plumbers. Typically, our repiping projects range from $4,500 for a two-bedroom, one-bath home to up to $15,000 for larger properties and more complex projects. We have an article that covers repipe cost factors in detail.

Schedule a free in-home consult, and one of our local repipe consultants will walk you through all your PEX repipe options and provide a written, fixed-price quote tailored to your home.

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