PEX Water Pipe

Crosslinked polyethylene, or PEX, is a polyethylene based polymer that has undergone crosslinking and can be used in potable water distribution. Currently, there are three methods for producing PEX tubing, the “Engle” or “Peroxide” (PEX-A) method, the “Silane” (PEX-B) method, and the “E-beam” (PEX-C) method. All three processes produce tubing that exceed the minimum requirements of ASTM F876 and are acceptable for potable water distribution applications. The final composition of these pipes is expected to be similar and all are included in the scope of this CP. Additionally, PEX has uses in plumbing, drainage, and fire surpression; however, these use cases were not the primary focus of this CP. Similarly to other plastic water pipes, PEX water pipes make use of additives, particularly antioxidants, UV stabilizers, and pigments. Antioxidants in PEX water pipes help reduce, mitigate, and in some cases even prevent the oxidation of PEX, which can occur primarily due to the chlorine in potable water applications. PEX water pipes also require UV stabilizers, such as hindered amine light stabilizers (HALS) to combat the effect of UV light degradation. Leaching has been observed with the use of PEX pipes, which is why preliminary flushing prior to use is critical, in addition to utilizing the PEX tubing at a temperature no greater than 180°F. If prolonged degradation occurs, pipe additives and degradation products may be found in potable water coming from any PEX pipe over extended period time (Lützhøft et al., 2013). There is indication of industry movement toward antioxidants with lower leachability such as sulfur containing phenolics and HALS (Sahar). See the Process Chemistry tab for leachants that were identified in our research.

The historical version of this CP can be found here: https://pharos.habitablefuture.org/common-products/2209588