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PEX is formed from a chemical called polyethylene. Polymer chains in its structure are further cross-linked by other links giving it strength. Such a chemical structure of PEX makes it extremely suitable for tubing that is used in radiant heating systems and for insulating high tension electric cables. Insulated PEX tubing ensures high performance even in the most extreme conditions and environment.

More recently, PEX has started replacing Polyvinyl Chloride(PVC) and Chlorinated Polyvinyl Chloride (CPVC) for tubing in water pipelines. PEX is the obvious choice for many such applications as it is robust and has better capacity to perform optimally even in high temperature conditions. Plumbing with PEX tubing is also convenient as it is highly resistant to corrosive chemicals that are usually present in a typical plumbing environment. PEX tubing repair is also easy, thus making it the most desirable option for diverse tubing applications.

How to Install PEX Tubing

The following procedure demonstrates the installation of PEX tubing for water lines.

Cutting Required Length of PEX Tube
Measure the length of PEX tube that is required for the water pipe. Cut a PEX tube of required length from the main PEX tube using a specially designed PEX tubing cutter. Ensure that the cut is sharp and made without leaving any protruding edges. To avoid the formation of such rough edges, hold the tube steady and cutter at 90 angle to it.

Crimp Ring and Fitting
Now slide a copper crimp ring over the one end of the cut tube. After that, force the PEX tubing onto one end of the PEX fitting (a metal object) and push it as far as it can go.

Settle the Crimp Ring
Now shift the copper crimp ring towards the PEX fitting so that it is at a distance ranging from 0.125 inches to 0.25 inches from its center.

Ring Crimper
Hold a ring crimper at an angle of 90 degrees to the copper crimp ring. Bend the crimp ring by closing the ring crimper completely over it. If the crimper is not at an angle of 90 degrees, it may lead to an uneven connection and even cause the tube to dent. Also, if the crimper does not entirely cover the crimp ring, it might result in a non-uniform crimp which will eventually lead to a situation where the PEX tube is unable to cover the ribs of the PEX fitting properly.

Go/No-Go Gauges
This step involves the Go/No-Go gauges test. This tool is used to check the acceptable tolerance levels of the particular work piece under test. As the name suggests, the tool has to check if the work piece qualifies the test or not, indicating Go or NoGo.

The Go gauge, in this case should be able of slide easily over the crimped ring whereas, the No-Go gauge should not be able to pass over it. In case the No-Go gauge manages to slide over the crimp ring, it indicates that the connection has not been done properly. The crimp ring must removed using a decrimper device. Cut the PEX tube close to the end of the fitting inside the tube and use decrimper. Repeat the above steps to fit the tube onto a PEX fitting with a crimped ring sealing the connection.

Get It Right
PEX tube is known to contract or expand by about one inch every hundred feet of tubing in response to every temperature change of 10 degrees Celsius. The installation should be done in such a way that it is able to accommodate these fluctuations in the length of the tube.

To cater to expansion and contractions of the tube, create a loop in the PEX, which is about 8 times the diameter of the tubing. Employ straps and hangers to support the PEX at every 32 inches, if the tubing is installed alongside a joist and at every 6 feet, if it is supported by a beam. In case of a vertical installation of the PEX tube, support should be provided at every floor. However, it must be ensured that the support hangers are loose enough to allow the movement of the tube.

Thus, PEX tube installation is quite an easy process and the next time a plumber is busy installing one in your locality, you will surely be in a position to observe his work, if not teach him a thing or two.