Crimp Fittings

These insert fittings use a crimp ring that is compressed around the PEX tubing and they can be made from either metal or plastic insert fittings. The compression of the crimp ring crushes the pipe around the insert barb and ensures that the fitting is secured. When these fittings are made of brass they are regulated by standard ASTM F1807, and can be used with PEX-a, PEX-b, or PEX-c.  Generally in the industry, they are considered to be primarily PEX-b or PE-RT fittings and are often referred to simply as “Brass Pex Fittings” or “Crimp Fittings”.  When these fittings are made of plastic or polymer they are regulated by standard ASTM F2159,  Generally in the industry, they are considered to be primarily PEX-b or PE-RT fittings and are often referred to simply as “Plastic Pex Fittings” or “Crimp Fittings”. For both types of fittings, before the connection is made, the crimp ring slides over the end of the PEX tubing, away from the end of the tube. The fitting is inserted into the end of the tube and the crimp ring is aligned and compressed. Since the fitting is a smaller diameter than the tubing, it restricts water flow. This can pose the need for an upsizing of the piping system. Furthermore, the strength of a crimp fitting is highest when the connection is first made, as over time the PEX tubing will resist the crimp ring fitting, especially PEX-a or PEX-c.