Author Topic: Plumbing question, 1-1/2” drain pipe  (Read 1790 times)

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Offline Michael Kellough

  • Posts: 4271
Plumbing question, 1-1/2” drain pipe
« on: May 07, 2019, 02:35 PM »
Just replaced some old brass drain pipe with new pvc hoping to avoid the catastrophic failure that resulted from corrosion.

Now I know why many people prefer metal pipe, plastic is noisy.

Is there any way to mitigate the noise (tape or spray-on rubber coating etc.) or do I have to go back to brass?

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Offline Svar

  • Posts: 1873
Re: Plumbing question, 1-1/2” drain pipe
« Reply #1 on: May 07, 2019, 03:12 PM »
Now I know why many people prefer metal pipe, plastic is noisy.
Really? [unsure] Never heard of this before.  [big grin]
I lived in houses with iron and PVC pipes. Did not notice any difference.

Offline Peter Halle

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Re: Plumbing question, 1-1/2” drain pipe
« Reply #2 on: May 07, 2019, 04:25 PM »
It was common here to use cast iron for the main stacks and then plastic for the laterals.  I wonder if a product like dynamat would help?

Peter

Offline Cheese

  • Posts: 6544
Re: Plumbing question, 1-1/2” drain pipe
« Reply #3 on: May 07, 2019, 04:31 PM »
You could try some of that adhesive rubber/lead sandwich that's used in automobiles to dampen sheet metal panels for sound systems.

https://www.parts-express.com/cat/sound-damping/409

A number of years ago I needed to put in a 3" drop for a bathroom. I actually installed the 3" pvc pipe and then looked into applying  an Acoustiblok rubber membrane. By the time I purchased the Acousticblok, the adhesive and the shipping, it cost more than just using cast iron pipe.

So I ripped out the pvc and installed the cast iron instead. 

I never knew they used brass for drain pipe. I wonder what caused it to corrode?
« Last Edit: May 07, 2019, 04:39 PM by Cheese »

Offline Slowlearner

  • Posts: 64
Re: Plumbing question, 1-1/2” drain pipe
« Reply #4 on: May 07, 2019, 05:54 PM »
Are you talking about brass tubular?

Offline Michael Kellough

  • Posts: 4271
Re: Plumbing question, 1-1/2” drain pipe
« Reply #5 on: May 07, 2019, 07:58 PM »
Yes @Slowlearner  it was just thin drawn brass tube. I guess it isn’t called pipe, no threads, like copper tube for supply lines.

Offline Slowlearner

  • Posts: 64
Re: Plumbing question, 1-1/2” drain pipe
« Reply #6 on: May 07, 2019, 08:02 PM »
I would think theres less noise w pvc bc of thicker wall

Offline Koamolly

  • Posts: 103
Re: Plumbing question, 1-1/2” drain pipe
« Reply #7 on: May 07, 2019, 09:52 PM »
You mean the P Traps underneath the sink?  If you are, Home Depot and others sell protectors that might help.  Hard to believe PVC is louder than thin brass.


Online Bob D.

  • Posts: 1361
Re: Plumbing question, 1-1/2” drain pipe
« Reply #8 on: May 07, 2019, 10:01 PM »
You could try some of that adhesive rubber/lead sandwich that's used in automobiles to dampen sheet metal panels for sound systems.

https://www.parts-express.com/cat/sound-damping/409

A number of years ago I needed to put in a 3" drop for a bathroom. I actually installed the 3" pvc pipe and then looked into applying  an Acoustiblok rubber membrane. By the time I purchased the Acousticblok, the adhesive and the shipping, it cost more than just using cast iron pipe.

So I ripped out the pvc and installed the cast iron instead. 

I never knew they used brass for drain pipe. I wonder what caused it to corrode?

Chromed brass was/is used for 1-1/4" and 1-1/2" traps and associated drain pipe under a sink or lav. Water with a pH that is off will corrode the pipe, as will chemical drain cleaners, and age. But cheap brass (as in very thin wall/light gauge) is often the culprit for an early failure, especially when the water is not treated and the pH adjusted. Old brass had lead in it and held up better, it was also usually made from heavier gauge tube. Before brass they used lead pipe and that tied into the CI by way of a brass ferule that was joined to the hub of a CI fitting or pipe with lead and oakum. You then used 50/50 or 40/60 'wiping solder' to join the lead pipe to the ferule. You literally wiped the molten lead on to form the joint by hand wearing a heat resistant glove and a wiping pad. A lost art and almost never done anymore. Not a 5 minute job. Never wiped any lead joints on the job, I did do one with my Father-in-law when I was an apprentice. But I did plenty of lead and oakum joints in the ditch; on scaffolds 30 feet up in the air; and working off ladders running pipe overhead. Scary stuff when you've got 5# of molten lead in the ladle and pouring a joint trying not to spill it cause it will burn you real fast. I never got burned luckily. Last lead joint I poured was 1983 working on restoring an old house I bought.

Found this video on YT. Not a first class joint but still serviceable. I have some Polaroids I took in my old house of the lead drains and closet bends before I ripped it all out and replace it with No-Hub CI pipe. Those was some beautiful work, it was a shame to cut them out but the lead was 80 years old and worn through.

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Offline DeformedTree

  • Posts: 597
Re: Plumbing question, 1-1/2” drain pipe
« Reply #9 on: May 07, 2019, 11:58 PM »
As was mentioned, iron stacks are in theory quieter than PVC.  It's stiff and has mass, much like it makes for good engine blocks, it does have nice properties for drain stacks.  My house had an iron stack, it's gone now, and maybe the PVC is louder, but doesn't matter, it will be packaged in walls in time with sound insulation around it.  Not corroding and clogging is more important.  It's pretty impressive when you snap the stack and see how good inside 60 year old iron can look inside, but still, the corrosion is there, spots get thing, crud builds up.  PVC avoids this.  If you want to see nasty, it's the line off a kitchen sink,   kitchen sink + iron = no good, of course getting garbage disposers banned and teaching people sinks are not universal waste disposal ports is a key to fix these issues.

I can't image your P-trap in plastic is any worse than brass far as noise.  It could be more of the geometry of your routing causing some odd flow thru it.   Stick with PVC, avoid sudden failures.

I would avoid the temptation to coat the PVC with anything, my concern is what you apply may have a reaction to the PVC and in time cause a failure.  Creating an unknown.  Also it might make spotting a leak harder. 

I think I have seen some formed wraps for going around P-traps. I think these are a bit for looks and to avoid condensation.  The would probably have some noise benefit.

Offline Michael Kellough

  • Posts: 4271
Re: Plumbing question, 1-1/2” drain pipe
« Reply #10 on: May 08, 2019, 12:07 AM »
The plastic is definitely louder than the brass was, at the end of it’s service when it was soft from corrosion and had a coating of 25+ years of residue. Maybe fresh brass would be just as noisy?

My wife hasn’t complained so I’ll probably just keep the pvc.

Offline Cheese

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Re: Plumbing question, 1-1/2” drain pipe
« Reply #11 on: May 08, 2019, 12:50 AM »
Michael my suggestion would be to lose the pvc. There’s nothing worse than to be sitting in the kitchen, chatting and eating and then have the children flush a toilet and have to listen to the sound of water rushing down the pipe as you’re eating your sushi. That ruins the entire meal.

It’s just flat out gross.

No, fresh brass will not be as noisy as it tamps down the noise issue while pvc exacerbates the noise.

The only place I’d install pvc is under the cement slab for DWV functions or for strictly venting situations, because then the noise is obfuscated by the cement overlay.  PVC is a good material, it just needs to be utilized in the proper situation.



 


Online Bob D.

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Re: Plumbing question, 1-1/2” drain pipe
« Reply #12 on: May 08, 2019, 04:39 AM »
"I think I have seen some formed wraps for going around P-traps"

Yes, for anti-sweat and for ADA installs, the latter to provide protection from contact with hot pipe and against banging into the trap.



4.19.4 Exposed Pipes and Surfaces.
Hot water and drain pipes under lavatories shall be insulated or otherwise configured to protect against contact. There shall be no sharp or abrasive surfaces under lavatories.

606 Lavatories and Sinks

606.5 Exposed Pipes and Surfaces. Water supply and drain pipes under lavatories and sinks shall be insulated or otherwise configured to protect against contact. There shall be no sharp or abrasive surfaces under lavatories and sinks.
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Offline Cheese

  • Posts: 6544
Re: Plumbing question, 1-1/2” drain pipe
« Reply #13 on: May 08, 2019, 09:16 AM »
The whole brass corrosion issue piqued my interest because brass has been used on boats for forever. Here's an interesting article on brass corrosion caused by "dezincification".

https://www.proboat.com/2012/07/beware-the-brass/

It seems that while that chrome plated brass trap is pretty on the outside, you don't know what brass alloy they used on the inside.  [eek]

I also ran across another interesting item. I saw several charts that said:
Brass plumbing is good for 30-40 years
Copper plumbing over 50+ years
Cast iron 75-100 years
« Last Edit: May 08, 2019, 09:50 AM by Cheese »

Offline Michael Kellough

  • Posts: 4271
Re: Plumbing question, 1-1/2” drain pipe
« Reply #14 on: May 08, 2019, 09:37 AM »
The only pvc in the house is under the kitchen sink so the worst noise case Cheese mentioned isn’t a risk (no kids either).

The sink is double basin style and the bad brass was the long horizontal piece joining the second smaller basin to the stout brass trap under the main basin.

I know I installed the old brass 27 years ago but can’t remember why it was two pieces soldered together. The corroded section was significantly thinner than the other piece which appeared to have at least another decade of service left to go.

I’ll look for a long piece of heavy brass. 30 years will be sufficient, assuming I won’t be around to fix it then.   [blink]
« Last Edit: May 08, 2019, 10:09 AM by Michael Kellough »