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REHAU PEXa Pipe: From Raw Material to Finished Pipe All Under One Roof
As a manufacturer of pipes made from PVC, PP, PE and PEX, REHAU's experience and knowledge of extrusion techniques is unmatched. We perform our own compounding, blending the various ingredients under very tight controls, right in the extrusion facility, so that the product goes from raw material to our finished PEXa pipe all under one roof. REHAU PEXa pipe exceeds all international standards for performance.
What Exactly is Crosslinked Polyethylene (PEX)?
Crosslinked polyethylene is polyethylene (PE) which has undergone a change in molecular structure whereby the polymer chains are chemically linked, crosslinked (X), with each other to form a three-dimensional network. The result is a flexible thermoset1 polymer with improved mechanical, thermal and chemical properties.
The Commercial Crosslinking Process – Pioneered by REHAU in 1968
REHAU uses the high-pressure peroxide method of crosslinking which is also known as PEXa. This method was pioneered by REHAU starting in 1968.
In this procedure, a very small amount of liquid peroxide is added to the base HDPE (high-density polyethylene) pellets, in a controlled mixing chamber at moderate temperature. Next, through a combination of high temperature and pressure developed within the extrusion machine, crosslinking occurs as the resulting compound is melted and extruded as crosslinked pipe. The peroxide is consumed in the reaction. The high-pressure peroxide method allows for a higher degree of crosslinking as compared to other methods. REHAU PEXa pipe is typically 80 to 85% crosslinked.
Similar to a Chain-Link Fence
Like a chain-link fence, PEX will expand with excessive pressure and then return to its original shape when the pressure is removed – so PEX pipe will usually allow the expansion of water that freezes inside when it has room to expand evenly along its length. Non-crosslinked pipe is rigid. It may resist higher pressure before initial expansion, but once it does deform and expand, it is forever changed and weakened.
Temperature and pressure ratings2 on PEX pipe include 160 psi @ 73.4°F, 100 psi @ 180°F and 80 psi @ 200°F3, with minimum burst pressure ratings as high as 475 psi @ 73.4°F. REHAU PEXa pipes typically burst at 850 to 900 psi when tested at 73.4°F.
- Withstands freezing and impacts
- Withstands surge pressures much better than copper, steel or CPVC, enough to avoid water hammer in many situations
- High burst strength and long-term pressure ratings
- Resistant to glycols, latex paints, silicone, urethane foam, most acids and bases
- Immune to corrosion from soil or water
- No pinhole leaks
Ease of installation
- Superior joining techniques
- No flame, no solder, no glue
- Lightweight and flexible
- More than 40 years of proven experience worldwide
PEX presents an overall lower cost to the environment compared to alternative piping materials.
- Greener production: PE is abundant, created by refining operations; no mining operations for ore, as with copper
- No chlorine is used in production of PEXa
- Reduced heat loss and condensation through pipes when compared to copper
- Saves energy, faster delivery of hot water
- Smooth wall and excellent flow characteristics reduce pumping costs
- Proven long life and durability
- Light weight of PEX reduces transportation costs
Our PEX pipe meets the performance requirements of North American standards ASTM F876 and F877, NSF Standards 14 and 61 and CSA B137.5.
1A thermoset polymer is analogous to a scrambled egg – once you mix the yolk and white, you cannot separate them. A non-crosslinked polymer, known as thermoplastic polymer, is analogous to chocolate – you can always melt and reform it into some other shape."
2Derived from an extrapolated time-to-failure prediction based on the minimum requirements as defined in ASTM F876. These pressure ratings are based on a “50-year strength value” which is a mathematical extrapolation based on the minimum requirements as defined in ASTM F876.
3Elevated temperature condition, please review REHAU's Technical Guidelines for further recommendations when operating at temperatures about 180°F