How crooked can you crimp pex rings?

Question

I had to add a supply valve for my refrigerator in my house. It's my first time working with pex. I added some Pex B to my existing Viega cold water line and used copper crimp rings with the appropriate tool. All of my crimps were checked with a go/nogo gauge.

My concern is that one of the crimps (the bottom one) is slightly off centered from the front as you can see from the image. I have no leaks in the system and it's working great so far, but I was curious if it warrants a re-crimp or if it will hold just fine if it's holding now.

I'd prefer to not have to re-crimp it, because there's only so much extra pex pipe under there and I'd prefer to not add too much complexity by adding another coupling to put some new line in and re-crimp the tee.

Answer 1

Your crimp ring looks good to me as well. It takes a lot of crooked to make a pex fitting leak. I've only managed a leaking pex fitting once, but I'd say if you're more than about 10 degrees off, you risk leaking.

However, for future reference, when I'm working in tight spaces where I'm concerned I might cause a leak, I use sharkbite fittings. While they are expensive, they are easy to add on and do not need a crimp tool. Sometimes it is difficult to get these large crimpers in small spaces and crimp straight. The cost of the fitting is well worth it if you prevent a leak.

Answer 2

I feel that rings fit generally pretty snugly on the pipes, if you managed to crimp it and it satisfies the following conditions, then it should be good:

1. Sharkbite crimp ring instructions state that assuming the pex pipe is well seated around the pex fitting, the distance between the edge of the crimp ring and the edge of the pex pipe should lie between 1/8" and 1/4".

   (the end goal there being that the ring should cover the area spanned by the two middle barbs on the pex brass fitting). As the comments mention, it's also better if it's done squarely to the pipe, but there is room for "angular" error.

2. Passes the go/no-go gauge to make sure it's crimped enough. This will ensure that the crimp ring applies enough compression to the pipe. The ring will cause the pipe to deform around these barbs on the fitting.

3. Doesn't leak.

PEX is generally forgiving, and if there's no leak now, there may not be ever a leak. I'm not a plumber though, I only have a few pex projects I've done. I say this also because just from looking at your pictures, I can't even tell which one is supposed to be the one that's askew -- so it doesn't look that bad.

If you're still uncomfortable, I can suggest a few more options:

• You can replace a section of pex between two fittings by cutting the ring and reusing the brass fitting, and you wouldn't have to redo any other connections. Search for "Crimp ring removal tool". The overall length of the pipe wouldn't change, but you may need to insert another straight coupling if this connection is far away from the next one.

• This looks like it's under a sink. It's a good idea to have a water leak detector. It works a bit like a fire alarm. There's a long-lasting battery, and when water splashes on it, it yells. Sometimes you get a home insurance discount when you add those to your house.

• Adding one more element on the way to the 1 or 2 fixtures shouldn't cause a noticeable difference in pressure, if that was a concern. The openings in the valves for the tap or the valves on a dishwasher are typically smaller than the size of the smallest diameter fitting along the 1/2" pex tubing.

This video is interesting: https://youtu.be/92x9z6uQbV4

You'll see a bunch of passing / non-passing crimp examples.

In the future

Rings have a tendency to crimp out of square with the pipe if they're oval, because it creates play along one axis. I experience this the most when I add rings to a pipe that is vertical (plumb), because I'll have to finger-pinch them a bit so they stay in place until I get the crimping tool over them (it's a two hander tool).

I'd recommend to pinch them as little as possible, or to toss out the rings that aren't initially (perfectly) circular, if you have plenty of spares to go around. After doing it for a while, it becomes second nature, and you can compensate a bit more for uneven rings.

Answer 3

As long as the crimp ring is correctly positioned over the brass barbs, you should be fine with it slightly crooked like that.

I don't have a source to back that up though, so maybe I shouldn't have answered.