Afrigather IRVING, TX — A brand new technical doc that addresses the essential variations between crosslinked polyethylene (PEX) tubing techniques with polybutylene (PB) techniques has been printed by the Plastics Pipe Institute, Inc. (PPI). The initiative was deemed essential to remove any confusion between the 2 merchandise due to issues related to polybutylene, which was discontinued.
Ready by PPI’s Constructing & Development Division, PPI TN-31 Variations Between Crosslinked Polyethylene (PEX) and Polybutylene (PB) Piping Programs for Potable Water Plumbing Purposes discusses some great benefits of fashionable PEX tubing and fittings as in contrast with PB tubing and fittings, which have been final bought within the US in the course of the late Nineties.
PEX shouldn’t be PB
“Briefly, PEX shouldn’t be polybutylene,” defined Lance MacNevin, P. Eng., director of engineering for PPI’s Constructing & Development Division, “however we’ve got discovered that some misunderstanding nonetheless persists within the business.
“Polybutylene tubing techniques have been launched into North America within the Seventies, however by the Eighties some PB techniques skilled untimely failures in potable water distribution techniques. Many failures have been attributed to the polyacetal materials, additionally known as polyoxymethylene or POM, used to mould the plastic fittings utilized in these techniques. Some failures of the PB tubing materials itself have been attributed to inadequate resistance to scorching chlorinated water or insufficient resistance to sluggish crack development.”
By the late Nineties, the first PB pipe grade resin producer selected to cease supplying it in North America. The PB tubing normal ASTM D3309 was withdrawn in 2010 and the fabric has since been faraway from plumbing and mechanical codes in USA and Canada.
Luckily, crosslinked polyethylene piping techniques had already been developed in Europe, with the primary PEX radiant heating techniques put in in 1972. The American normal for PEX tubing, ASTM F876, was printed in 1984 and PEX was adopted into plumbing codes in 1997. At present, the North American PEX business is prospering in each residential and business building.
Completely different Pipes – Completely different Properties
MacNevin continued, “Simply as varied kinds of metals, reminiscent of metal and copper, have completely different properties, varied kinds of plastics even have completely different properties. Not all steel pipes carry out the identical, and never all plastic pipe and becoming supplies carry out the identical both. Because of fashionable polymer expertise, PEX piping techniques carry out in ways in which present superior reliability and security when in comparison with polybutylene piping techniques.”
PEX techniques have a number of key variations and benefits over the discontinued polybutylene pipe parts that have been bought in North America till the Nineties:
- PEX is a crosslinked materials, including larger long-term stability in opposition to inner stress at excessive temperatures, improved toughness, and diminished creep (materials stream) underneath compressive hundreds at becoming connections, whereas PB materials shouldn’t be crosslinked.
- PEX tubing has thicker partitions than PB tubing. All PEX tubing has a regular dimension ratio (SDR) of 9, vs. SDR 11 for PB. The thicker wall of PEX provides higher mechanical power and resistance to break.
- PEX tubing is required to exhibit chlorine resistance. Obligatory chlorine resistance testing in response to ASTM Check Methodology F2023 requires that every one PEX tubing used for potable water functions shall be examined to fulfill a minimal extrapolated lifetime of at the least 50 years. Such testing was not in place for polybutylene tubing.
- PEX techniques don’t use polyacetal insert fittings. PEX techniques for potable-water plumbing use fittings made out of lead-free brass or bronze, copper, chrome steel, or polymers reminiscent of polysulfone (PSU) and polyphenylsufone (PPSU), each of which have demonstrated very excessive ranges of chlorine resistance.
In keeping with product requirements from ASTM, AWWA, CSA, and NSF, the testing necessities for at the moment’s PEX techniques are way more stringent than for PB techniques of the previous. Third-party certification companies additionally require strenuous high quality management testing for PEX techniques, together with frequent unannounced inspections of vegetation and annual monitoring and re-testing.
PPI TN-31 and Extra
PPI TN-31 accommodates the checklist of historic requirements for PB piping techniques plus a comparability of PB and PEX crimp ring becoming dimensions. Entry the total content material of PPI TN-31 at www.plasticpipe.org/buildingconstruction and go to the “publications” tab, then click on on BCD Technical Literature.
Extra info and information about stress pipe supplies used for plumbing and mechanical techniques can be found from the PPI Constructing & Development Division at www.plasticpipe.org/buildingconstruction
