Flexible Reduction Coupling on a pressurized pipe

[Ami.l]

Hi all experts and thanks in advance for your help!

I live in Alameda County in northern CA in a hillside house.
The pipe leading up to the street main sewer line is a 3" PVC, about 400 ft long, with an elevation difference of about 40 ft.

~2 Years ago, I had professional plumbers repair my sump pump float. They also replaced the last pipe section to the pump with a new check valve.
They used a rubber reduction coupling (shown in attached photo) to connect the 3" main pipe to the 2" pump pipe.

Last month, the coupling failed, shifted out of place, causing a spill of the entire pipe content into my back yard. you can do the math, it's ~150 gallons... at ~17.5 PSI...

My question is:
Is this coupling allowed by code to be used on pressurized lines?
I see it (or very similar item) on home depot web site, where it explicitly says this is for DWV: http://www.homedepot.com/p/3-in-x-2-in-PVC-DWV-Mechanical-Flexible-Coupling-P1056-32/100372295

If the plumber did commit a code violation, where is the relevant code section, and what do you think is the extension of the plumber's liability for this spill?

Thank you for your thoughts!

Ami

 

[Terry]

Most of the check valves for sump pumps have rubber couplings similar to that.
I've never had to install one with 40 feet of head, and 400 feet of distance. That's a lot of pressure on a fitting like that. I don't know if you can go back on the plumber for that, but for the repair I would consider a fitting made for pressure, a water supply fitting. That is more like a drainage fitting, which most of the time, has been working good enough. But 40' and 400'? Sounds like you need to up the game on that.

 

[Sponsor]

 

[Ami.l]

Most of the check valves for sump pumps have rubber couplings similar to that.
I've never had to install one with 40 feet of head, and 400 feet of distance. That's a lot of pressure on a fitting like that. I don't know if you can go back on the plumber for that, but for the repair I would consider a fitting made for pressure, a water supply fitting. That is more like a drainage fitting, which most of the time, has been working good enough. But 40' and 400'? Sounds like you need to up the game on that.

Hi Terry and thanks for your prompt reply.
I have already replaced the rubber coupling with a schedule 40, solid PVC one cemented in place...

My question is really about the code; is using this rubber coupling in a pressurized line a violation of plumbing code or not?
I would like to clearly establish liability here as the plumber refuses to accept any of it.

Thanks,

Ami

 

[Reach4]

I think you are saying that you have a sealed septic pit pumping household sewage uphill under pressure.

I have already replaced the rubber coupling with a schedule 40, solid PVC one cemented in place...

I can't help on the code. I will point out that with 400 ft, there is a lot of expansion and contraction with temperature. http://www.charlottepipe.com/Documents/PL_Tech_Man/ExpansionandContraction.pdf has the gory details. Page 57 and 57 describe the use of a "loop" to allow contraction and expansion. If you still have access, you might want to convert your repair.

Because your pipe has mostly been buried for a while, you will see less temperature change than you would right after installation. But still there are temperature changes including changes due to the contents.

Also, is that solid PVC pipe, which is pressure rated? Foam core pipe looks the same and is the same size. So while things are uncovered, you might read the markings if you want to know. Since it is California, and they usually use ABS for foam core pipe there, it might make it more likely that you have pressure rated PVC. Around here, most 3 inch PVC pipe would be the non-pressure type, and you have to check the markings if you want it for pressure.

 

[Ami.l]

I think you are saying that you have a sealed septic pit pumping household sewage uphill under pressure.


I can't help on the code. I will point out that with 400 ft, there is a lot of expansion and contraction with temperature. http://www.charlottepipe.com/Documents/PL_Tech_Man/ExpansionandContraction.pdf has the gory details. Page 57 and 57 describe the use of a "loop" to allow contraction and expansion. If you still have access, you might want to convert your repair.

Because your pipe has mostly been buried for a while, you will see less temperature change than you would right after installation. But still there are temperature changes including changes due to the contents.

Also, is that solid PVC pipe, which is pressure rated? Foam core pipe looks the same and is the same size. So while things are uncovered, you might read the markings if you want to know. Since it is California, and they usually use ABS for foam core pipe there, it might make it more likely that you have pressure rated PVC. Around here, most 3 inch PVC pipe would be the non-pressure type, and you have to check the markings if you want it for pressure.

Hi Reach and thanks for the detailed reply.
You are correct that the pipe is sealed and constantly under pressure.
The tank itself is not sealed. The pump has a float switch, and the check valve keeps the pressure in the pipe when the pump is off.

There is room for the pipe to move slightly. I have 2 more 2" heavy duty rubber couplings, and the end also has some room to move as the pump is 'hanging' from it in the tank. I'm attaching a photo of the whole setup with the new piping.
I am in north CA, so extreme weather is not an issue.
The pipe is Schedule 40 PVC. It is from the late 80's when the house was built.

Thanks again for your detailed reply.

I hope someone can help me with the code question.

Thanks,

Ami

P.S. See attached photo of setup with new piping

 

[hj]

IF it worked for 2 years, I doubt that anyone would accept liability for it.

 

[Jadnashua]

I don't know which exact coupling you have, but this series from www.fernco.com https://www.fernco.com/products/flexible-couplings/stock-couplings lists 4.3psi as the maximum test pressure. One would assume, I know that's dangerous, that that is likely about 2-300% of the expected pressure it is designed for. IOW, it should NOT be used on a pressurized system.

If you can read the brand and type from the one that failed, I'd call the manufacturer and talk to their tech support people. It sounds like it is not a suitable item for this application, and the plumber is required to install things that are. I'm not a lawyer or a plumber, but my layman's opinion is that he would be liable because he used an unsuitable fitting. IMHO, it should have been caught by the inspection, but then, not all of them are very good at their jobs other than collecting the fees...

 

[Ami.l]

Thanks @jadnashua - They didn't even obtain a permit, so there was no inspection...