Types Of Pex Pipe

PEX-a is manufactured produces a PEX with around 85% crosslinking of the polymer chains in the pipe. This is important because the greater the crosslinking, the more flexible and durable the pipe. It also provides shape and thermal memory that allows repairs of kinks in the pipe with a simple shot of heat from a heat gun.

PEX-b which produces 65% to 70% crosslinking, and PEX-c produce 70% to 75% crosslinking. These PEX manufacturing methods result in a stiffer piping product that is not as flexible as PEX-a and is also not viable for kink repairs. (This means you have to add a coupling if you get a kink in PEX-b or PEX-c pipe.) In addition, because of their lower crosslinking, these pipe types can experience micro-cracking when expanded. This can lead to leaks in fittings when using the expansion method.

There are several other joining methods for PEX pipe, including crimp and clamp, which use a smaller-diameter fitting that is inserted into the pipe and then a crimp ring or clamp ring fastens down around the outside of the pipe. 

There are also push-to-connect, tool-less options, as well as expansion with compression, which uses expansion to insert a larger-diameter fitting. Then a compression sleeve is pulled over the outside of the pipe to hold the fitting in place.

While the push-to-connect option is quite easy and simple to make, some professionals prefer not to use it due to its questionable durability. Also, for the expansion-with-compression system, the two-step process of first expanding the pipe then adding the compression sleeve adds additional time to installs, which is not the most efficient.