scope:

The intent of this Technical Note is to give guidance to the end user for determining appropriate design life calculations of crosslinked polyethylene (PEX) pipe and tubing in high-temperature applications, defined as operating temperatures above 180°F (82°C) for the purpose of this document. Not all PEX manufacturers allow operating conditions above 180°F for their tubing. Applications with such hightemperature exposures may include commercial hydronic distribution systems such as high-temperature radiator/baseboard piping, district heating piping, and certain types of waste heat systems.

The Background information in this Technical Note is provided to explain how PEX pipe and tubing, conforming to standards such as ASTM F876, ASTM F2788 and CSA B137.5, are suitable for typical applications such as hydronic radiant heating/cooling, hydronic distribution, snow and ice melting, and geothermal ground heat exchangers at operating temperatures up to and including 180°F.

Note 1: For PEX materials, "tubing" refers to products whereby the actual outside diameter (OD) is 1/8 inch larger than the nominal size and is described as copper tube size (CTS). Product standards ASTM F876 and CSA B137.5 apply to PEX tubing. "Pipe" refers to products whereby the actual OD matches that of steel pipe of the same nominal size and is described as iron pipe size (IPS), or products where the actual OD matches the nominal size. ASTM F2788 applies to PEX pipe. The terms "pipe" and "piping", as well as "tube" and "tubing", are used interchangeably in this document.

Note 2: See PPI TN-53 GUIDE TO CHLORINE RESISTANCE RATINGS OF PEX PIPES AND TUBING FOR POTABLE WATER APPLICATIONS for more information on the use of PEX tubing in hot chlorinated potable water applications.