PEX Information

Everything you need to know about plumbing with PEX

PEX plumbing, PEX fittings, PEX tools

PEX (or crosslinked polyethylene) is part of a water supply piping system that has several advantages over metal pipe (copper, iron, lead) or rigid plastic pipe (PVC, CPVC, ABS) systems. It is flexible, resistant to scale and chlorine, doesn't corrode or develop pinholes, is faster to install than metal or rigid plastic, and has fewer connections and fittings.

PEX tubing is made from crosslinked HDPE (high density polyethylene) polymer. The HDPE is melted and continuously extruded into tube. The crosslinking of the HDPE is accomplished in one of three different methods.

PEX plumbing has been in use in Europe since about 1970, and was introduced in the U.S. around 1980. The use of PEX has been increasing ever since, replacing copper pipe in many applications, especially radiant heating systems installed in the slab under floors or walkways. Interest in PEX for hot and cold water plumbing has increased recently in the United States.

Advantages of PEX Plumbing

  • Flexible PEX tube is manufactured by extrusion, and shipped and stored on spools, where rigid plastic or metal piping must be cut to some practical length for shipping and storage. This leads to several advantages, including lower shipping and handling costs due to decreased weight and improved storage options.
  • PEX plumbing installations require fewer fittings than rigid piping. The flexible tubing can turn 90 degree corners without the need for elbow fittings, and PEX tubing unrolled from spools can be installed in long runs without the need for coupling fittings.
  • Attaching PEX tube to fittings does not require soldering, and so eliminates the health hazards involved with lead-based solder and acid fluxes; PEX is also safer to install since a torch is not needed to make connections..
  • PEX resists the scale build-up common with copper pipe, and does not pit or corrode when exposed to acidic water.
  • PEX is much more resistant to freeze-breakage than copper or rigid plastic pipe.
  • PEX tubing does not transfer heat as readily as copper, and so conserves energy.
  • Water flows more quietly through PEX tube, and the characteristic "water hammer" noise of copper pipe systems is virtually eliminated.
  • PEX plumbing installations cost less because:
    • PEX is less expensive than copper pipe.
    • Less time is spent running pipe and installing fittings than with rigid pipe systems.
    • Installing fewer fittings reduces the chances for expensive callbacks.

PEX Tubing

The terms PEX pipe and PEX tube have been used interchangeably, however some manufacturers distinguish beween the two by manufacturing to different inside/outside diameters. For example, PEX pipe may be manufactured to IPS-ID (iron pipe size, inside diameter controlled) sizes with varying thickness to meet pressure requirements, while PEX tube may be manufactured to CTS-OD (copper tubing size, outside diameter controlled) sizes, commonly with a standard thickness of SDR-9 (standard dimension ratio).

The PEX tube manufactured to CTS-OD sizes is the most common, with available sizes including 3/8", 1/2", 5/8", 3/4" and 1". On this website, "PEX tube" refers to this common CTS-OD product.

Before extrusion, the HDPE can be pigmented to yield color-coded pipe. Common PEX tubing colors are "natural" (hazy clear, unpigmented), white, black, red and blue. The red and blue colors are used to help plumbers and homeowners distinguish between hot and cold water supply lines. The tube will be marked on the outside to show which standards it meets.

As it is produced, PEX is wound onto spools for storage and shipping. A typical spool of 1/2 inch PEX will hold 1200 feet of tubing.

PEX connection methods

Standard Connection Method

The standard method for connecting PEX pipe to brass PEX fittings uses a copper crimp ring and a PEX crimping tool. The copper crimp ring is inserted over the pipe, the fitting is inserted inside the pipe, and the copper ring is crimped over the pipe and fitting using the PEX crimping tool. Tools, fittings and crimp rings are available from several suppliers. Information about testing standards for this method can be found on the ASTM standards page.

Expansion Fitting Method

The expansion method involves using an expansion tool to increase the diameter of the PEX tube. Special expansion fittings are inserted into the expanded tube, which shrinks back to shape around the fitting. A plastic ring is then pressed over the fitting to insure a tight connection.

This method was developed as a proprietary solution, and is currently available from one company. Information about testing standards for this method can be found on the ASTM standards page.

SSC Method

The SSC (stainless steel clamp) method uses special clamps designed for PEX connection. The fittings used here are the same used in the "Standard Connection Method" above, but in this method the SSC fastens the PEX tube to the fitting. A special "SSC crimping tool" is used to tighten the clamp around the tube and fitting. Information about testing standards for this method can be found on the ASTM standards page.

Compression Method

Standard compression fittings can be used to make connections between PEX tubing. For moderate to large size jobs this method is more expensive than using the Standard Connection Method, since compression fittings cost more than PEX fittings.

"Push-fit" and other proprietary methods

Several companies offer specialized fittings that will connect PEX to PEX or to copper, PVC and other materials as well. These fittings use one or more of several technologies such as EDPM O-ring seals, stainless steel gripping teeth, and threaded compression nuts. These fittings are faster and easier than most competing methods, but cost more per fitting than standard PEX fittings.

PEX fittings

PEX fittings are generally made of brass, although some vendors are offering bronze, copper and engineered plastic fittings for PEX. The characteristic ridges on the "insert" part of the fitting distinguish a PEX fitting from other fittings (see pictures below). The ridges, the PEX tube and the crimped copper ring all work together to form a high-pressure seal.

PEX (top) to
PEX (top) to
PEX (top) to
copper (sweat)

PEX tools

To work with PEX tubing using the standard crimping method, three basic tools are needed: the main crimping tool(s), a pipe cutter, and a de-crimping tool.

The pipe cutter is used to make a clean, square cut before inserting the tubing into the fitting.

The main crimping tool can be purchased in several configurations from various vendors. One popular model has the capability to crimp either 1/2" or 3/4" PEX tube, while another uses interchangeable crimp heads to work with any of the PEX tube sizes.

A de-crimping tool is designed to remove the copper crimp ring from the tube and fitting. Various designs all work by cutting the copper ring. Fittings can be easily re-used.

Prices for these tools can vary widely depending on the brand. Buying all the tools together in a kit can reduce the price. Lower prices are also available online using Ebay, Google or Yahoo to search for quality vendors with discounted prices (including warranties).

PEX Tubing Compatibility

Most PEX tubing is compatible with all the various connection methods, with PEX-Al-PEX being the exception.

      Compatible PEX Connections
PEX Tubing Manufacturer PEX Product Name Tubing Type Standard Crimp Ring SSC (Stainless Steel Clamp) Proprietary Connection Types Compression Fittings
IPEX Kitec XPA PEX-Al-PEX Compatible Compatible   Compatible
IPEX CTS SDR9 PEX Tubing PEX Compatible Compatible Compatible Compatible
Rehau RAUPEX® PEX Compatible Compatible Compatible Compatible
Upanor / Wirsbo Wirsbo AquaPEX® PEX Compatible Compatible Compatible Compatible
Vanguard Vanex PEX Compatible Compatible Compatible Compatible
Vanguard COMPAX-L PEX-Al-PEX Compatible Compatible   Compatible
Viega Pexcel PEX Compatible Compatible Compatible Compatible
Viega FostaPex PEX-Al-PEX Compatible Compatible   Compatible
Viega Pextron (Oxygen Barrier) PEX Compatible Compatible Compatible Compatible
Weil-McLain Qual-Pex (Oxygen Barrier) PEX Compatible Compatible Compatible Compatible
Weil-McLain AlumiPex PEX-Al-PEX Compatible Compatible   Compatible
Zurn Zurn PEX (Non Barrier) PEX Compatible Compatible Compatible Compatible
Zurn Zurn PEX (Oxygen Barrier) PEX Compatible Compatible Compatible Compatible

PEX Fittings Compatibility

The Standard Crimp Ring method is the most popular method. The fittings listed under the Proprietary Connection Type column are unique to specific manufacturers, and may use unique tools. Most of these are not compatible with other PEX connection methods.

Standard PEX fittings can be used with the Standard Method and the SSC (clamp) method.

Compression fittings can be used to make connections with PEX tube, but do not use PEX fittings. They are listed to show the manufacturers that make compression fittings specifically for PEX tubing.

      Compatible PEX Connections
PEX Fitting
PEX Fitting
Product Name
Standard Crimp Ring SSC (Stainless Steel Clamp) Proprietary Connection Type Compression Fittings
IPEX Kitec K1 Brass w/ O-ring No No   Kitec K1
IPEX Kitec K2 Brass w/ O-ring No No Kitec K2  
Rehau Everloc® Fittings Brass No No Everloc  
Sioux Chief PEX Fittings Copper Yes Yes    
Brass Yes Yes    
Upanor / Wirsbo ProPEX Fittings Brass or Plastic No No ProPEX QS-style
Vanguard CrimpSert Brass Yes Yes    
Viega ProPress Copper No No ProPress  
Viega CombiFlex
Bronze No No Viega Press  
Viega PureFlow Fittings Bronze No No Viega Press  
Zurn Qick/Sert™ 1
Brass Yes Yes    
Zurn PolyAlloy Fittings Plastic Yes Yes    
Zurn QickTite Fittings Plastic No No   QickTite
Zurn Polymer Fittings Plastic No No QickClamp  

PEX Tool Compatibility

Standard PEX Crimp Tools are available from several vendors, while special PEX tools are required for proprietary PEX connection methods.

    Compatible PEX Connections
PEX Tool Manufacturer PEX Tool Name Standard Crimp Ring SSC (Stainless Steel Clamp) Proprietary Connection Type
Mil3 Compact Crimpmaker Yes No  
Rehau Comboloc, Versaloc,
No No Everloc
Ridgid Viega ProPress Tool No No ProPress
Ridgid Viega Press Tool No No Viega Press
Sioux Chief PEX Crimp Tools Yes No  
Sioux Chief PEX Cinch Tools No Yes  
PEXCaliber™ Crimp
Yes No  
PEXCaliber™ Cinch
No Yes  
Upanor / Wirsbo ProPEX Expander Tool No No ProPEX®
Viega Viega ProPress® Tool No No ProPress
Viega Viega Press Tool No No Viega Press
Wheeler Rex PEX Ring Crimper Yes Yes  
Zurn PEX Crimp Tools Yes No  
Zurn PEX Cinch Tools No Yes  

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