Understanding The Three Different PEX Tubing Grades

Not all PEX plumbing supplies are created equal. In addition to being made in multiple different colors (generally red, white, blue, and gray), PEX tubing is also made in three common grades. It’s important for everyone in the plumbing or radiant heat flooring business to be familiar with these grades, so that they can respond to clients if and when they have questions about which pipe is being used. Knowing the pros and cons of each of these PEX plumbing supplies is also important for projects involving certain insurance companies or local building codes. Some grades are permissible while others are prohibited, and it’s important to choose the right one so that there aren’t any complications further down the line.

“Grade” Doesn’t Indicate Quality

The first thing to understand about PEX tubing is that while the different selections are separated into “grades”, this isn’t exactly a measure of quality. Rather, these “grades” refer to the way that the PEX was manufactured.

PEX-A

This type of PEX tubing is produced using Peroxide. This style of production is known as the “Engel” method because it was invented by a man named Tomas Engel. This is generally considered to be the most flexible of all the PEX types; it has absolutely no coil memory and any kinks that do appear in the tubing can be fixed quickly with a heat gun. As such, PEX-A is the most expensive grade of PEX tubing.

PEX-B

This type of PEX tubing is produced via the "Silane" or "Moisture Cure" method of cross-linking. PEX-B is manufactured by a large number of companies and thus is one of the most commonly available. PEX-B is known for being very resistant to chlorine and oxidation, and has the highest bursting pressure. It’s slightly stiffer than PEX-A but it’s also quite a bit cheaper. Kinks in PEX-B can only be repaired by splicing using coupling.

PEX-C

This type of PEX tubing is made using “Electronic Irradiation” method of cross-linking, also known as "Cold" cross-linking. It’s known for being softer than PEX-B, as well as more environmentally-friendly to manufacture. While it’s the least resistant to kinks, PEX-C has little to no coil memory.