USA Expert Plumbing

PEX-A vs PEX-B pipes

By USA Expert Plumbing Editorial Team. Updated . 1 min read.

Short answer

PEX-A and PEX-B are both approved for hot and cold drinking water. PEX-A is more flexible, can often be repaired with heat if kinked, and usually uses expansion fittings. PEX-B is stiffer and cheaper and usually uses crimp or clamp rings. Both last for decades when installed correctly; the fitting system is often what decides.

In this guide
  1. Side by side
  2. Expansion vs crimp fittings
  3. Which to choose
  4. Good practices for any PEX
  5. Repair tips

PEX (cross-linked polyethylene) has largely replaced copper in new homes and repipes. The letter after it refers to how the plastic was cross-linked, which changes how it handles and which fittings it uses.

Side by side

FeaturePEX-APEX-B
How it is madePeroxide (Engel) methodSilane (moisture cure) method
FlexibilityMost flexible; easier to routeStiffer; tighter bends need fittings
KinksOften repairable with a heat gunKinked sections are cut out
Common fittingsExpansion fittings with ringsCrimp or stainless clamp rings
ToolsExpansion toolCrimp or clamp tool
PriceHigherLower

Expansion vs crimp fittings

With PEX-A, the pipe end and a ring are expanded, a fitting is inserted, and the pipe shrinks back around it. The result has a full-bore opening and a very secure joint. PEX-B joints use a metal ring squeezed over the pipe and a barbed fitting inside, which narrows the flow slightly. Both are reliable when done with the right tool and gauge.

Which to choose

  • Whole-house repipe: either works; many pros prefer PEX-A for flexibility and fewer fittings.
  • DIY repairs: PEX-B with clamp rings is inexpensive, and the tools are affordable.
  • Cold climates: all PEX tolerates freezing better than rigid pipe, though no pipe should be left to freeze.

Good practices for any PEX

  • Keep it out of direct sunlight; UV damages it.
  • Do not connect it directly to a water heater; use the length of metal pipe or connector the manufacturer specifies.
  • Support runs properly and allow for expansion on long straight runs.

For repipe prices, see our whole house repiping cost guide.

Repair tips

  • Use the fitting system that matches your pipe and ring type.
  • Cut PEX square with a PEX cutter, not a hacksaw.
  • Check crimp rings with a go/no-go gauge.
  • Push-fit couplings work for quick repairs on either type.

Common questions

Can PEX-A and PEX-B be connected?

Yes, with compatible fittings, but use the fitting system each pipe is rated for.

Is PEX safe for drinking water?

PEX certified for potable water is widely approved for hot and cold drinking water lines in U.S. homes.

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