PEX Tubing installation details (C) D FriedmanPEX Tubing & Piping
Cross-Linked Polyethylene PEX Piping Installation, Inspection, Safety
     

  • PEX PIPING INFORMATION - CONTENTS: properties, installation, safey. What is PEX pipe, where is it used, & how is it installed. PEX properties, PEX history & key dates, PEX failure class action information, PEX compared with copper piping, PlumbPex class action settlement, Kitec class action settlement. PEX piping leaks, reliability, & PEX used for building water supply piping, radiant floor heating & other heating applications. Update on Pex fitting de-zincification problems reported from the field. Pex dezincification research citations.
  • POST a QUESTION or READ FAQs about PEX polyethylene plastic supply and drain piping, gas piping, etc.
  • REFERENCES

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PEX cross linked polyethylene piping guide:

This article describes the properties of Pex Tubing or Piping, Cross-Linked Polyethylene (PEX). We discuss the uses of PEX tubing for water supply & in heating applications.

We describe the several differnt types of PEX tubing connector systems used including PEX crimp fittings, PEX compression fittings, PEX expander fittings, PEX Press-Fit connectors, and PEX Shark-Bite fittings and connectors.

We also discuss the ongoing debate of Pex versus Copper or other piping choices, with the pros and cons of each, and we include a literature review of and comment on the question is PEX tubing or piping safe to use or does it leach contaminants into our water supply. This article also includes the history of the development, use, & standards for PEX piping.

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Pex Tubing or Piping, Cross-Linked Polyethylene (PEX)

PEX Water Piping installation (C) D Friedman Galow Homes

PEX and PB plastic pipe are used for water supply in buildings use mechanical fittings (crimp and compression type) and we have found some installers using PEX tubing in low temperature heating applications (see below). PEX piping is also referred to as "cross-linked polyethylene" piping or just "PEX".

Our photo (left) illustrates PEX water supply piping being installed in a New York home.

Photo courtesy Galow Homes.

[Click to enlarge any image]

 

Article Contents

Applications & Properties of PEX Piping

Installing both building water supply piping and heating supply piping (and radiant heating) can be significantly faster using PEX tubing because of its ability to bend around turns, avoiding some elbows, 45's and other fittings.

PEX piping is used in both hot and cold water applications (see the blue and red colors below). By convention the builder uses blue PEX for cold water and red PEX for hot water supply piping lines.

Generally you will find PEX piping or tubing marked with the nominal pipe size, wall thickness, and pressure rating and other information (see the illustration just below).

Temperature and pressure ratings for PEX, according to Zurn Manufacturing's engineering specifications is 160 PSI at 73°F, 100 PSI at 180°F, and 80 PSI at 200°F.

PEX piping marking guide (C) Zurn Manufacturing

Illustration of PEX tubing markings - courtesy Zurn Manufacturing (permission requested 12/2010). [Click any image or table to see an enlarged, detailed version.]

When installing PEX piping, care must be taken that the pipe does not contact heating ducts.

If the pipe freezes, it is less likely to burst than and copper piping. Also, most types of plastic water pipe tend to sag and should be well supported by hangers

Watch out: PEX plastic water piping should not be installed outdoors or exposed to sunlight for long periods. The red and blue PEX piping shown below (right) were delivering hot and cold water in a newly-constructed home. The larger black ABS plastic pipe is probably a drain line.

Watch out: do not use plastic piping nor any other type of piping in applications for which it was not intended, or the result could be dangerous. For example, do not use PEX tubing for LP or natural gas piping.

Plastic piping (C) Daniel Friedman Polybutylene water piping guidelines Carson Dunlop Associates

PEX Tubing Connectors: Types, Tools, Requirements

Watch out: a variety of patented PEX tubing push-fit and clamp connecting fittings (at least six types) and connector crimping tools are on the market. You may not obtain a proper and secure PEX connection if you mix tubing connector fittings and crimping tools improperly. We recommend choosing a specific connector type and crimping tool and using it consistently at a given plumbing installation.

Examples & Photographs of the various types of PEX fittings and the special tools used include:

PEX Clamp fitting installation (C) D Friedman

 

 

 

  • Clamp type PEX fittings (photo at left) using a brass connector and stainless steel clamp-rings (e.g. Hydro-Pex clamping tool). These connectors were in use in our PEX installation photograph above. Popular, easy to use.

    Note in our PEX photo at left that on the cold water (blue) Tee fitting one of the clamp fittings remains to be completed. (Photo courtesy Galow Homes).

PEX Clamp fitting installation (C) D Friedman

  • Crimp type PEX fittings (photo at left - Crimp type PEX fittings in a Haddonfield New Jersey home) (e.g. Watts Radiant PEX cramping tool) using Hydro-Pex fittings.

    The copper crimp rings are used with most PEX connectors.

 

 

 



Shark Bite type PEX fittings (C) D Friedman

  • Compression type PEX fittings (photo at left) (radiant heating and other applications) uses three parts (connector, compression ring or ferrule, threaded nut) to connect PEX tubing to a radiant heating manifold.

    Threaded nut and ferrule are used with an insert to prepare the tubing for connection to the manifold.

    No special tools are needed and compression type PEX fittings work with standard and Pex tubing.

PEX Tubing installation details (C) D Friedman

  • Expander type PEX fittings (photo at left, Expander type PEX fittings in a Tivoli NY home), e.g. ProPEX brass connecting fittings and the ProPEX expander tool from Uponor (formerly Wirsbo PEX fittings).

    The expander tool actually expands or "stretches" the PEX tubing to accept the connecting fitting. A ProPEX ring of larger diameter covers and completes the expanded fitting connection. Popular with professional plumbers.

    Our PEX tubing photo (left) illustrates three PEX installation details: use of expander-type PEX fittings, and at the photo bottom (blue cold water piping) a protective sleeve or bushing at the floor joist penetration, and a steel nail plate to protect the tubing from puncture by ceiling drywall (to be installed).

    Watch out: use only with PEX A-quality fittings. lower quality tubing will not make secure PEX connections with this method.

    Note: in best construction practices all holes drilled through structural floor joists (shown at left) would be made in the center of the joist, not near the bottom as in our photo.

  • Press-fit type PEX fittings from Wirsbo, Mr. PEX, and Viega. (do not assume you can mix fittings and tools among these three manufacturers). Use the Viega PEX press tool requires using Viega fittings, for example.

    The Viega press PEX fittings are sold separately from the required stainless steel press PEX rings OR you can buy Viega pex press fittings that include the crimp ring already combined with the fitting.

    When using the Viega method with the integrated fitting and crimp ring you'll need to look closely to assure that you have inserted the fitting fully into the tubing before crimping the sleeve using the Viega tool. Works with standard and Pex tubing.

Shark bite push fit plumbing fittings (C) D Friedman

  • SharkBite PEX push-fit fittings (photo at left) - push-in fittings (also work with copper and CPVC). No tools or rings are required.

    We used the SharkBite fitting shown at left to temporarily cut and discontinue active hot and cold water plumbing lines during a building renovation/addition project. The fittings avoided having to drain piping and solder end caps onto pipes that were later to be further cut back, excavated, and permanently capped below the slab.

  • PEX Tubing cutter - used to make a clean end-cut, e.g. Wirsbo (now Uponor) PEX cutter

 

Types of PEX Cross-Linked Polyethylene Tubing

Four methods of creating cross-linked polyethylene, each possibly imparting different properties to the PEX piping or tubing, include

  1. PE-Xa = using peroxide, developed by Engel, PAM, Frankische and others
  2. PE-Xb = using silane, developed by DOW Corning / Sioplas
  3. PE-Xc = using electronic irridiation
  4. PE-xd = using AZO (Gustavsberg-Lobonyl) - not currently in production

- Bean (2007)

Standards, Listings and Approvals for PEX Plumbing Systems

The following standards and building codes list at least some elements of PEX plumbing systems.

  • ANSI/NSF Standard 14 (NSF International)
  • ANSI/NSF Standard 61
  • ASTM F876 (American Society for Testing & Materials)
  • ASTM F877
  • ASTM F1807
  • CAN/CSA B137.5 (Canadian Standards Association)
  • California Plumbing Code - 2010
  • IPC (International Plumbing Code)
  • IRC (International Residential Code)
  • UPC (Uniform Plumbing and Mechanical Code)
  • U.S. State & Local Regulations or Canadian Provincial or Local Regulations

Pex Tubing / Plumbing use History & Dates

In the United States the use of PEX tubing in residential buildings for water supply & heating piping has been approved for use in all fifty states and in Canada in all of the provinces.

  • 1933: (accidental) discovery of polyethylene following an explosion at Imperial Chemial Industries in England
  • 1939: pilot plant production of polyethylene in the U.S.
  • 1940's: BASF in Germany experiments with polyethylene tubing
  • 1950: beginning research on cross-linked polyethylene plastics.
  • 1954: Hoechst experiments with Hoestlan high density polyethylene & predicts very long life of the tubing (more than50 years). Early tubing needed further development to withstand high temperatures.
  • 1965: Engel patents an economical process for successfully cross-linking polyethylene
  • 1967: First licensed use of the Engel patent to produce Vernetzes polyethylene i.e. PEX
  • 1970's: PEX formulation improved by Lenman, Agren et als.
  • 1975: Golan produces PEX-a & PEX-c later sold to American & Canadian interests
  • 1975-85: standards for PEX piping developed by Stufen, Liedelt, Stagge & Seydel et. als.
  • 1980: PEX piping introduced for use in the United States & Canada. DIN 4726 created limiting Oxygen gas transmission rate, a factor in tubing success. (Oxygen permeation / outgassing created problems in hot water heating applicatyions.)
  • 1984: ASTM F876/877 Lenman published for PEX Tubing
  • 1984: oxygen-related boiler corrosion problems reported associated with "non-barriered" pipe used in heating systems leads to continued research on the oxygen diffusion problem
  • Latter 1980's: PEX tubing radiant heat applications developing in North America and elsewhere
  • 1987: DIN 4726 standard finalized.
  • 1989: CSA 137.5 for PEX published by Lenman
  • 1990-2007: production of PEX a,b,c (various methods of producing cross-linked polyethylene tubing), PEX-AI-PEX, and PE-RT tubing.
  • 1995: begin use of IPEX-manufactured Kitec fittings later found to fail & leak
  • 15 May 1999: beginning of period of defective Plumb-Pex defective component installations in North America - for class action settlement purposes
  • 2005: IPEX recalls Kitec®, or Kyetec brand of brass plumbing fittings
  • 2009: California approved PEX for use in all homes.
  • 2007: California, one of the last adopters, did not approve the use of PEX (cross-linked polyethylene tubing) for household plumbing until 2007 (on a case by case basis)
  • 31 March 2012 - end date for filing claims re: Court ordered homeowner notification program for defective Plumb-PEX components
  • 22 September 2013: ending date for filing claims for the Court ordered homeowner notification program for defective Plumb-PEX components

PEX Pipes vs Copper Piping: which is preferred?

Reader Question: Pex vs. Copper Water Supply Piping - which should I use?

Question: my daughter is doing extensive renovations on her house and the question has come up whether to use PEX or copper in the plumbing.

I did a google search and the informations is conflicted; see below. [We read & also expanded the writer's original four web link citations in the article below - Ed.] Do you have knowledge of, and opinions about, this controversy? Any thoughts would be helpful. Thanks. Elisha Fisch, New York 2/17/2013

Reply:

PEX hot and cold water piping installed during new construction (C) Daniel Friedman Eric Galow 2012 2013Elisha I've moved this discussion on Pex pipes vs copper pipes to its own article at

We will continue to monitor the PEX health and contamination question and will update here. Contact Us by email to send field reports or to report on new studies.

Copper Water Supply Piping

The same PLASTIC vs. COPPER article above lists propertie of copper water supply pipes when used in buildings and compares copper pipe performance with that of plastic.

A bottom line opinion is that each plumbing material has its own vulnerabilities as well as advantages & disadvantages.

We discuss types of copper piping and their intended uses and copper fittings beginning at COPPER PIPING in buildings.

Plumb-PEX Plumbing System Class Action Settlement - PEX piping leaks

In March 2012 people who own or previously owned a building where Plumb-PEX plumbing components were installed are notified of a proposed class action settlement involving Radiant Technology, Inc. and Uponor, Inc who sold Plumb-PEX insert fittings and stainless steel PEX tubing clamps.

Details about this PEX plastic piping failure are now at PlumbPex® PEX LEAKS & LAWSUIT

Kitec Brass Fitting & Related IPEX Plastic Pipe Leaks: Class Action Settlement

The Kitec system was a collection of brass plumbing connectors intended for use with PEX type plastic piping. Kitec, also in some sources spelled Kyetec is a brand of brass plumbing fitting that was recalled in 2005 by its manufacturer, IPEX, due to its tendency to quickly corrode. - Wikipedia [30]

Kitec plastic pipe and fittings has agreed to settle class-action suits in the United States and Canada for $125 million. The piping system that is the subject of this action was used in roughly 292,000 U.S. and Canadian homes beginning in 1995.

Details about the Kitec plastic class action suit are given in a link just below.

Question: is PEX the same as Kitec® ?

Is PEX the same as Kitec? How does one tell distinguish between Kitec and PEX? - Anon

Reply: Kitec was an individual brand of PEX pipe subject of a class action settlement

Anon,

PEX (cross-linked polyethylene piping) is a general term for a type of plastic piping used in water supply, heating, and other applications.

Kitec® is a specific brand of PEX tubing that was subject of a class action settlement with an end-date for filing claims of 31 March 2012.

  1. Details about plastic pipe leaks by pipe type & brand are in this topic home page:
    PLASTIC PIPE LEAK CAUSES
  2. Kitek® PLASTIC PIPE LEAKS, CLASS ACTION SETTLEMENT discussion is found within that article.
  3. PEX PIPING INFORMATION gives details about PEX across the product range
  4. Information about all types of plastic piping used in buildings starts
    at PLASTIC PIPING ABS CPVC PB PEX PVC.

Pex De-zincification Update & Research: field failure photographs of Brass PEX Pipe Fitting Corrosion & Leaks

Brass PEX pipoing fitting corrosion (C) 2014 InspectApedia.com & Anon

[Click to enlarge any image]

Above left: brass tee corrosion appearing both on the Tee-fitting body (red arrow) and around the end of the PEX tubing (green arrow) on water piping in a 2009 home.

Details about corrosion, leaks, & possible dezincification problems at brass connectors used in PEX piping systems are
at PEX BRASS CONNECTOR LEAKS

Research on PEX Piping vs Drinking Water Contamination

  • Kelley, Keven M., Alexandra C. Stenson, Rajarashi Dey, and Andrew J. Whelton. "Release of drinking water contaminants and odor impacts caused by green building cross-linked polyethylene (PEX) plumbing systems." Water research 67 (2014): 19-32.

 

Continue reading at PEX BRASS CONNECTOR LEAKS (discussing de-zincification and leaks at PEX connectors) or select a topic from the More Reading links shown below.

Or see PLASTIC PIPE LEAK CAUSES including

Suggested citation for this web page

PEX PIPING INFORMATION at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

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