Pipe coupler installation 1

[sennafan]

I am looking at a water delivery pipe failure and need a little help. The pipe is a 2" I.D. steel/iron line from the main and the failure occurred at a coupler that was used above a new shutoff valve. The coupler is a friction fit (non-threaded) where it attaches to the distribution line that runs through the building. The pipe and coupler are out of alignment by approximately 3.3 degrees. Visually it looks like the misalignment is worse. I cannot seem to find information for these fittings regarding maximum allowable axial misalignment either as industry standards, specific product standards, or code requirement. I need to answer the question "was the installation faulty?" and if so need to be able to point to the standard/regulation that was violated. Any help or advice would be greatly appreciated.

Thanks,
Sennafan

 

[MikeHalloran]

Your description of the coupling is not sufficient to identify it or to disambiguate the various generic styles of couplings available.

Please provide a manufacturer, part number, or a detailed description, or a photograph. Thanks.



Mike Halloran
Pembroke Pines, FL, USA

 

[MiketheEngineer]

I would check the MFG's specs or call them

Was this in St. Louis??

 

[sennafan]

I do not know exactly what the fitting is - it appears to be threaded onto a "T" above the shut-off valve and a compression fitting to the distribution pipe. Hopefully the attached photo helps.

 

[sennafan]

I may be google challenged, but I have not been able to find any manufacturer specifications for allowable misalignment and I do not know the make or model of this particular coupler. The installation is not in St. Louis.

 

[MikeHalloran]

I've seen them before, but I don't remember what to call them.

Notice how the body is belled out, to allow clearance for misaligned pipe ends. I think the packing inside the packing nut on the end will distort enough to seal any pipe that you can get into the body.

If the contract doesn't include the word "workmanlike" or something like that, and the joint is not leaking, I don't see a basis for rejection.

... against current practice in the USA. My father wouldn't have tolerated it as a customer, nor submitted it as a workman. Today, if you complain about something like that, you'll get a whole lot of attitude, and a repair that's even uglier and will leak sooner.


Mike Halloran
Pembroke Pines, FL, USA

 

[gerhardl]

I do not know if this will help, but....

For larger pipelines (water mains) there exists sliding dismantling or connection pieces of steel (two concentric tubes) or nodular iron wich can be tightened both for the concentric part and the grip around the pipe-ends they connect to.

For theese products there exists some guidelines on how much they can be out of alignment, but mostly the tolerences are not given or exists, describing mounting to be concentric with the original pipeline.

Theese types will normally tolerate (personal experience, no producer backed information) up to 2-5 (up to 7?) degrees skew. Two points: this will be less tolerable for a short length one-piece item. The dismantling pieces will be in two parts and can also be thightened at ends to avoid leakage.

You have a one-piece short item, no mechanical thightening possibillities.

Leaking is obviously pointing out that something is wrong. The leak could be caused by one or several causes in combination:

-Unsuited product, material and fastening/mounting methode
-Non-coaxial/linear mounting
-False mounting else (what do mounting instructions say- allowable minimum overlapping?)
-Dirt or uneven pipe-ends (left materialparts from cutting ends?)
-Lacking of clamping of pipeline, pipeline moving by temerature, shocks from waterhammer when closing valve, mechanical thrust when closing valve.
- Overpressure (by testing?) or general pressure disforming the plastic material


..and perhaps some others.

The conclusion is that all above goes back to company responsible for mounting the installation. (Perhaps exception: if someone else has selected all material components and set measures for mounting of all components and clampings on pipeline, but again a good installation company should have reacted.)

I would not have used a plastic component at this point, and clamping around valve and on pipeline seems unsatisfactory.

 

[sennafan]

Thanks for the replies gentlemen. The belling of the coupler does look like it allows for the amount of visible misalignment. I have checked the plumbing code and see no absolute requirement for clamping pipe runs except for vertical support and seismic bracing. This pipe extends upward about 5' to an elbow and then a long horizontal run. The pipe passes over the top plate of the wall framing in the picture. When the joint failed the top plate was lifted off the studs about 1" (pulled the 16d plate nails right out of the tops of the studs). The plumber is claiming that vibration from nearby construction (vibratory compaction) caused the failure. I am left thinking he is correct that vibration can work a joint apart, but only if it is not really correctly installed. I am not finding any inarguable mistake from what I've read or what I'm hearing here. Anyone know if I've missed something in the plumbing code about fixing pipes?

Thanks again,

Sennafan

 

[MikeHalloran]

Well, that's a horse of another color.

I don't know what a code might say, but pipes joined with couplings like that _must_ be anchored, because hydrostatic pressure can separate the joints, just like the rod oozing out of a hydraulic cylinder.

Roughly similar joints used in boats optionally come with metallic teeth embedded in the rubber packing to grip the pipe for exactly that reason.

The force exerted is supply pressure times the gross area of the pipe; no external vibration needed.


Mike Halloran
Pembroke Pines, FL, USA

 

[sennafan]

Thanks Mike,

Any idea if there is a specific code section (mechanical or plumbing) that requires anchorage to resist the hydrostatic pressure? From what I can see the plumber did anchor the end of the pipe that slipped, just did not understand that wall plate-to-stud nailing is not really effective in tension.

 

[MiketheEngineer]

Last week - in St Louis we had a water main break (1 1/2'' line I think) that "blew". Said to be misaligned and poorly installed. It was in a rather new Federal Courts building and ruined like 17 stories of offices, court rooms, etc.

Just seem coincidental??

 

[sennafan]

MiketheEngineer:

People have been saying the federal courts are "all wet" for years. Sounds like the plumber's defence ought to be "what's changed?".

My case is a 2" line in an office-warehouse that reportedly flooded the building to a depth of around 3" when the first guy in discovered it at 5:30 AM.

I started my career in St. Louis - 2 years with IL Dept of Mines and Minerals, then five years at two different small consulting firms before moving to the north-west in 89. We may have some mutual aquaintences if you're career is in buildings.

 

[MiketheEngineer]

Mostly residential, light commercial & industrial. Also into wood and steel trusses and pole barns on/off for the last 30-35 years.

Ring a bell?

 

[sennafan]

Sure does - I did strip centers, apartment developments, industrial new and modifications, commercial buildings, 3 to 5 story steel frame office buildings, new design and renovation/redevelopemnt projects. When I left I couldn't drive more than a couple miles without passing by or within a couple blocks of some site I'd work on.

Carr and Associates and Leonard Weintraub and Associates are the two consulting firms I worked for. Both very good guys to work for in different ways and both had good staff to work with and learn from.

 

[MiketheEngineer]

Never worked for them - but both are/were well respected.

 

[sennafan]

Bill Carr was/is one of the sharpest engineers I've ever met. Amazing memory for obscure structural info and where to find articles/information on just about anything. Leonard was accomplished and modest - a very good, gentle teacher and probably the nicest guy I ever worked for. Learned a lot from both of them and got pushed a lot to get better by both of them.