# SDR 35 to SCH 40 ?



## The Dane (Feb 19, 2015)

I have to replace an SDR 35 clean out tee outside the building going to a septic tank. It was just a tee on its back and not a wye. Someone previously have broken it by the looks of it and not me. As I used it to clear a clog I noticed it when the water went down. I know that SDR 35 has the same diameter as SCH 40 so I glues into it. I was wondering since the inside diameter is bigger because of the thinner wall. Would I get too much restriction if I cut out and repaired with a SCH 40 wye and a fernco coupling on each side or should I replace with SDR 35 again? I would like SCH 40 just to make sure such a broken fitting does not happen again.

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## Plumbus (Aug 4, 2008)

The OD of 4" SRD 35 is 4.215"
The OD of 4" sch 40 PVC is 4.5"
They make a bushing to transition from SRD35 (or SDR26) to PVC 40.








Or, you can replace with an SDR 26 wye since the wall thickness on SRD 26 fittings is about a 1/3 more than SDR35.


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## The Dane (Feb 19, 2015)

Plumbus said:


> The OD of 4" SRD 35 is 4.215"
> The OD of 4" sch 40 PVC is 4.5"
> They make a bushing to transition from SRD35 (or SDR26) to PVC 40.
> View attachment 128906
> ...


Thanks. Hmm maybe I was wrong but I could have sworn I have seen it be glued together. Well I wasn't really asking about the size or if it would fit together anyway. 

What I wanted to know is weather I can use SCH 40 for repair without it creating a "hump" or small restriction that would hold back water or make for a spot where solids could catch on and create a clog? Just to make sure next time it gets snaked it won't break like the SDR 35 did. It's going to be connected with fernco couplings and not glued so I can use eighter SDR or SCH just fine. I think SCH 40 is better but would hate to create a "hump" so that's the real question, to repair with SDR 35 or SCH 40? What would you guys do? This is a picture looking down the clean out tee on its back. You can see that it must have been a cabke that got shoved down too hard at some point in time.









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## Plumbus (Aug 4, 2008)

Then average inside diameter of 4" SDR 35 is 3.975". The average inside diameter of 4" PVC 40 is 3.998". So, you can potentially have a .023" hump at the downstream PVC to SDR35 connection. That's not much of an obstruction. I see more potential for problems from using Fernco couplings. Even AC (metal clad) couplings can offset.


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## The Dane (Feb 19, 2015)

Plumbus said:


> Then average inside diameter of 4" SDR 35 is 3.975". The average inside diameter of 4" PVC 40 is 3.998". So, you can potentially have a .023" hump at the downstream PVC to SDR35 connection. That's not much of an obstruction. I see more potential for problems from using Fernco couplings. Even AC (metal clad) couplings can offset.


Well I don't see any other way to replace a fitting in the ground other than fernco couplings as you can't pull the pipe away and back in to a glued joint. Well with the inside being so close I'll probably ho with the SCH 40 then as I think SDR 35 is junk.

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## hewhodigsholes (Oct 28, 2020)

The Dane said:


> Well I don't see any other way to replace a fitting in the ground other than fernco couplings as you can't pull the pipe away and back in to a glued joint.
> 
> Sent from my SM-G970U using Tapatalk


Grind the stop out of a coupling, use like a copper slip coupling, then glue the snot out of it.


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## skoronesa (Oct 27, 2015)

The Dane said:


> Well I don't see any other way to replace a fitting in the ground other than fernco couplings as you can't pull the pipe away and back in to a glued joint. Well with the inside being so close I'll probably ho with the SCH 40 then as I think SDR 35 is junk.


A couple years ago I was in the middle of no where connecting SDR35 and Sched. 40 and we wanted it to be solid because it was near huge pines so I used a fernco AND the shield from a 4 band no hub.

Ain't cheap but I felt good about it.


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## skoronesa (Oct 27, 2015)

For the small hump you might get, just ream/chamfer the sched 40 good and when you do the connector fudge it a bit so the bottoms of the pipes line up nice and the hump is at the top.


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## Plumbus (Aug 4, 2008)

No need to grind the stop, PVC Couplings w/o stops are available on line.





Product Listing p130-040 PVC-Fittings-Couples-No-Stop at FlexPVC.com


p130-040 PVC-Fittings-Couples-No-Stop %%name%%




flexpvc.com









4" PVC DWV Repair Coupling - No Stop


COUPLING, REPAIR PVC DWV 4" HUB X HUB NO STOP




www.markspp.com


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## hewhodigsholes (Oct 28, 2020)

Plumbus said:


> No need to grind the stop, PVC Couplings w/o stops are available on line.
> 
> 
> 
> ...


Yeah, I've gotten those before. The learning curve is a little steeper than the copper no stop couplings.. Can't always source one locally though, so sometimes I'll going out the stop.


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## sparky (Jan 8, 2014)

Just go back with sch 35 and be done with it,if it gets broke again you will fix it again and be the hero and make money


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## skoronesa (Oct 27, 2015)

sparky said:


> Just go back with sch 35 and be done with it,if it gets broke again you will fix it again and be the hero and make money


If he knowingly uses weak pipe and it fails again wouldn't he be the villain?


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## The Dane (Feb 19, 2015)

sparky said:


> Just go back with sch 35 and be done with it,if it gets broke again you will fix it again and be the hero and make money


What skoronesa said. If I as a professional see a problem caused by inferior material or design. Would the only professional thing to do, not be to replace it the propper way with the propper material?

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## sparky (Jan 8, 2014)

skoronesa said:


> If he knowingly uses weak pipe and it fails again wouldn't he be the villain?


Why heck no,you are way over thinking things sko lololololol also he will be the one roto rooting it from now on so he will know not to slam his cable down in the tee


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