CTS and IPS name different dimensional families used to identify pipe and tubing sizes. CTS means copper tube size; IPS means iron pipe size. The names describe dimensions, not necessarily the material: a plastic product can use either family. Matching nominal size labels across those families does not establish a compatible connection.
CTS and IPS name different dimensional families used to identify pipe and tubing sizes. CTS means copper tube size; IPS means iron pipe size. The names describe dimensions, not necessarily the material: a plastic product can use either family. Matching nominal size labels across those families does not establish a compatible connection.
Why the same size name can differ
The Copper Development Association's handbook lists copper tube nominal sizes and outside dimensions. Charlotte Pipe's plastics manual and dimensional catalog identify CTS CPVC products separately from its other pipe-size families.
Those product tables show why a nominal fraction is only part of a parts description. A fitting made for one outside-diameter family may not accept another, even when both packages appear to name the same size.
The material designation supplies different information. Calling a product CPVC does not by itself say whether it follows CTS dimensions or another pipe series. Color is also inadequate identification evidence; use markings, product documentation and the actual dimensional table.
End connections have to match too
A size family does not tell you whether the end is a socket, spigot, thread, compression connection or another listed joint. Both the dimensions and the approved connection method must agree with the specified pipe.
An adapter may deliberately bridge two systems. Its two end descriptions should identify what each side accepts. It should not be selected just because the larger end appears to slide over an old piece of pipe.
Measurements can help identify an accessible product, but a measurement alone does not establish its pressure, temperature or drinking-water approval. The existing material may also be worn, coated or partly concealed, leaving an identification limit that needs to be resolved.
Information that prevents a wrong part order
Give the installer the pipe markings, material, nominal size and any known dimensional family. Ask the quote to name both sides of a transition and the approved adapter. A close photograph of the markings can be more useful than an estimate from the pipe's bore.
Our nominal pipe size entry explains the naming convention. Pipe schedule addresses wall dimensions. CTS and IPS answer which size family is intended; they do not replace either the material specification or the connection instructions.