Problem with Mueller fitting at customer side of water meter

[Etbrown4]

We all know there are ips and cts sizes, and that's not the problem on this job.

This Mueller fitting is made onto the meter yoke, so there is no easy replacing it.

Installing a new house side water service we replaced 3/4 ips polyethylene pipe with the same thing, with the same od.

Going back in to the old Mueller fitting, the rubber seal is somewhat loose on the new pipe (and now, it's somewhat loose on the old pipe as well) Acknowledge that the rubber will tighten up when threaded down.

Once tightened properly, however it will not hold. Yet it was holding pressure before we replaced the service line. One other thing. City Water pressure before was at 95psi.

Suggestions appreciated

 

[Gary Swart]

If the fitting is part of the meter, it is the city's responsibility, otherwise it is your problem. Sometimes meters can be set in a manhole that makes it difficult to get wrenches on to the parts. You may want to consider a plumber. Yeah, I know there is a minimum charge, but if you break the meter that change will be peanuts compared to a new meter. As far as the water pressure is concerned, 96 psi is way too much. You need a pressure regulator valve and set the pressure down to around 60 psi. In addition, you will need to install a thermal expansion tank to absorb the water pressure build up from you water heater. The PRV will create a "closed system" which prevents the expansion from being absorbed by the city main. The result of not having the tank is the T/P safety valve on the water heater will open and dump several cups of water every time the heater operates. You should check with the place you buy the PRV to verify whether or not it has a bypass feature that, if it does, would eliminate the need for the expansion tank. Some new PRVs have this feature. I recommend caution working DIY on the meter.

 

[Sponsor]

 

[Etbrown4]

We've worked on several dozen meter yokes with this same setup, and with the Mueller brass compression fitting it's not unusual.

Problem here is the rubber bushing will not grip the 3/4ips polyethylene pipe. We've check the od of the new line and it's the same od as the line we replaced.

The city pressure in this area has been 90+ for at least 20 years that know of, and there's never been a problem reported by any area customers.

Most supply houses now just carry the Ford fittings and none in our area have the Muller style.

There is no doubt that all that's needed is the inner rubber seal.

The problem is finding one in Muller brand, as the Ford and Muller will not interchange.

 

[Wet_Boots]

If you are seeing multiples of this situation, you need to get the proper Meuller replacement parts. You haven't said, but I assume you are transferring the inner stainless-steel pipe liner/support from the old poly line to the new one.

The rubber compression gasket with the metal gripping ring should be Meuller part number 89599

The liner for 3/4 IPS poly is part number 505141

 

[Etbrown4]

Sure enough the problem was the rubber seal had failed.

Upon close inspection the seal has an internal metal ring or band.

That internal band had broken and one part of it was overlapping the rubber seal. Thus a leak.

This is made more complicated because almost no plumbing supply houses in our area stock anything Mueller, as it's mostly municipal use.

So far the water works sales guys seem to sell mostly fittings and few repair parts.

That 89599 part number is the right one (thanks to the poster Wet_Boots!). Mulller lists them here, among others: http://www.muellercompany.com/files/Section8C 8.pdf

To see a cutaway of the fitting and seal here is a link. it shows the band over lappping itself, http://www.muellerflo.com/files/Water Section 06.pdf

One last observation. With the pn 89599 and 3/4 ips pipe or tube, the fit is real loose prior to tightening. It's so loose that you may think you have the wrong size. Prior to tightening, there is a gap of up to an easy 1/16" between the seal and the tube.

Apparently there is a lot of movement by that seal, upon tightening, and so far we're holding under 95 psi as it and others nearby have for 20+ years!

 

[Wet_Boots]

IPS poly is a bit problematical, because the OD is not a set number. The ID is a set dimension, so it properly fits over barbed insert fittings. The OD will vary depending on the rated pressure and the resin type used. When high-density resin became commonplace, the OD shrank a bit, for pipe of a specific pressure rating.

Undoubtedly, the compression fitting was originally designed for medium density poly, with a larger OD

 

[Etbrown4]

Yes, it is a sloppy fit, but with the new water service line being identically the same od as the replaced line, we should theoretically be ok. The original line lasted over 20 years, and would have lasted longer if it had not been for some lousy plastic insert fittings used underground at the building end of the line. Heretofore we've had those insert fittings break in similar installations, with a ground tremor, or minor earthquake, and maybe just with time!

We refuse to use the plastic insert fittings, as brass is the only thing with will last! Plus the plastic will creep out of the pipe under higher pressures.

 

[Wet_Boots]

While I wouldn't go for it myself, there are insert fittings made of brass, and combined with premium clamps like the Lox-On strap clamps, you could secure most any poly water main. Since they're good enough to suspend a submersible pump on, they can handle just sitting there underground.

The problem with plastic insert fittings, is that there are some that are made from polypropylene, which show that ability to pull out of a clamped connection. Insert fittings of PVC don't show that weakness, but I'd never use them on a water main in earthquake territory.