Pump outlet busted... Ugh.

[Z06Boricua]

So I just looked out the window of my breakfast nook and noticed that my water level was about an inch below the waterline tile, just into the top of the plaster. After shouting a very loud expletive, I ran out to the equipment pad to find the pump running, straining to find water, and this lovely scene:

There is no breakage, all threads are intact. Anyone know what would cause the outlet pipe to blow out of the pump housing like this? I also noticed that the pipe going into the pump inlet is slightly loose. This stinks.

 

[JasonLion]

I'm speechless.

I've never seen anything remotely like that.

The fix should be obvious, if tedious. I just can't begin to imagine how that happened.

 

[Z06Boricua]

I know! If that union were to fail, I'd expect it to shear off the pipe at the base of the threads, a clean break. I find it completely bizarre that it would just let go like that. I've got someone running to Lowe's for me to pick up another 2" threaded joint and a coupler. If it threads in loosely and seems to me like it could come out again, I may just end up cementing the **** thing in there to be done with it. I'm more worried about the pump running dry between the time the water level dropped low enough to suck in air and me turning it off. :\ There's no way to know how long it ran dry for. Pump turned on at 0900, I noticed it at 1110. Somewhere between that time it started sucking air through the skimmer.

 

[Richard320]

Hmmm... I wonder if the thing ran dry and got so hot that it started building up steam pressure and the housing or threaded adaptor got soft enough to blow? I guess you'll know when you get it going again. Good idea on the threaded coupler, in case you did smoke the pump or warp the housing.

 

[gtemkin]

Bizarre. Is the distance separating the pump and the pipe a result of you positioning it that way or was that the way you found it? If that was the way it was found, I'd have to say it must of been under some additional strain from being mis aligned so much.

The other thing to consider is that many pump ports are straight pipe threads not tapered pipe threads. They're meant to be used with an o-ring boss fitting. A tapered pipe, barely screwed into a straight pipe boss, with the misalignment you have may have separated on its own however i'd be surprised that it was ever able to seal in the first place.

Very odd.

Edit: I just noticed in the photo that the inlet side of the pump has a fitting that's fully bottomed out yet you mentioned it seemed loose. I think that further suggests that tapered threads into straight threads may have played a role here.

 

[Z06Boricua]

Alright, gtemkin wins the thread. After cutting the pipe a few inches above the failure so I could recouple it, I took a good look at it and immediately noticed that the threads were tapered, with deformation about 2-3 threads closest to the base. This is all that was holding the pipe to the outlet housing, along with a silicone caulk gasket. I replaced it with a 2" fitting with straight threads, adding some teflon tape as well. Good to go! The builder will be getting a nice call from me on Monday morning. Here are some pics of the fitting:

Thanks for your help!

 

[gtemkin]

One more thought.

Although you've already got it solved using a straight thread fitting, one additional possibility is that the tapered pipe fittings might have worked well enough if it wasn't for the fact that they might have been too long. From the picture showing the pump output port, it looks like there's a ledge at the bottom of the threaded area. That ledge looks like it's smaller than the thread diameter. If the tapered fitting is too long, it will bottom out and start "jacking" and striping the threads off the fitting. Since the tapered thread was only fully engaged on a very few threads, the jacking effect could easily partially strip those threads.

Glad you got it resolved.

 

[Z06Boricua]

Actually, you may be right. I don't think the fitting was completely bottomed out on the pump housing, hence why he plumber filled it with silicone. The little silicone ring I pulled off of it was probably around a 1/4" thick. Now I'm starting to wonder if perhaps the plumber designed it that way as sort of a pop-off in the case of an overpressure condition...

One more thought.

Although you've already got it solved using a straight thread fitting, one additional possibility is that the tapered pipe fittings might have worked well enough if it wasn't for the fact that they might have been too long. From the picture showing the pump output port, it looks like there's a ledge at the bottom of the threaded area. That ledge looks like it's smaller than the thread diameter. If the tapered fitting is too long, it will bottom out and start "jacking" and striping the threads off the fitting. Since the tapered thread was only fully engaged on a very few threads, the jacking effect could easily partially strip those threads.

Glad you got it resolved.