Tips of the Trade - prepping old Cast for Fernco?

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WJP

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I seem to have a very small small leak on two Ferncos I installed yesterday. I have cut a wye into my 4" cast iron waste line for a new basement bathroom and used 2 Ferncos intended for cast to PVC. The gap from Cast to PVC is 1/4" on each end so no sagging. The Ferncos are good and tight but not over tight/deformed. This is on the horizontal and there is no other possible source of the leaks (the wye/branch is capped for the moment and dry). The leaks are only at the Cast end of the Ferncos - the PVC ends are dry.

I am thinking the bit of corrosion on the exterior of the cast is preventing a full Fernco seal - are there tips of the trade for this? Perhaps filing or a bit of silicon?

From the cross section I cleanly broke out the 110 year old cast looks solid with no interior corrosion and still very thick and even walls - the only corrosion evident is the bit on the outside surface from soil moisture. It's not actually that rough - certainly no more than any number of online images/videos I've seen but it seems there must be enough roughness for this issue..

Thanks all.

John
 
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FullySprinklered

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That was my best shot. I'm thinking 110 years ago most folks had an eight foot air gap in their plumbing. Pipe sizes likely were not standardized until much later.
 

Terry

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I will guess that your cast is 4-1/8" OD, which would mean you would need a Mission copper by cast no-hub coupling.
I never use no-hub couplings on cast that old. It's always copper sizing.

pasco-torque-wrench.jpg
 
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Daniel Collick

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I will guess that your cast is 4-1/8" OD, which would mean you would need a Mission copper by cast no-hub coupling.
I never use no-hub couplings on cast that old. It's always copper sizing.
Sounds like a winner! Although I've never had an issue using "no-hub" couplings, I do prefer the Proflex adapter couplings for a snug fit.
The heavy duty Husky(4 band) cast iron couplings work well too. I believe the outside O.D. of cast iron is only a fraction smaller than the outside O.D. of ABS or PVC DWV. After you've placed one side of the coupling/band around a section of pipe to be installed(do this on both sides of the pipe/fitting section to be installed) fold the other side of the coupling over itself. Once you've done this on both ends insert the new section in between the cast iron and fold the couplings/bands back over the cast iron. It's not that hard once you've done it. Place the bands on afterwards and use a Sekonk torque wrench to tighten them down.
 

Jadnashua

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Fernco is a company name in the same vein as Kleenex is...people call tissues Kleenex. The most common fitting Fernco makes may be the rubber sleeve with hose clamps, and people tend to call them Fernco's. What you need is also made by Fernco (which has a huge assortment of products similar to Kleenex brand stuff, or Scotch tape), but is a banded/shielded coupling. Proflex happens to be their product name of one type of coupling.
sc-proflex-main.jpg
 

Cacher_Chick

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I grind off any raised type from the casting and then hit it with coarse sandpaper before installing the coupler. I put one over heavy coats of paint and it seeped like that. Won't make that mistake again.
 
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