Cast Iron dimensions

[Mrosenb]

I have a cast iron stack that I’m replacing. I have outside diameter 3.58in and outside diameter 4.27in. Is this normal? Shouldn’t the ID be closer to 4in? Am I ok using PVC with the Fernco P3000-44?

 

[Terry]

Here is their chart for sizing. Depending on the brand and year, the dimension of cast can change.

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[Mrosenb]

My concern is with connecting the pipes where the inside dimensions have almost a half inch difference.

 

[Jeff H Young]

sounds like 3 1/2 inch pipe 3.550 id 4.000 od off by less than a 1/32on od . I don't think I've ever dealt with 3 1/2" .

 

[Mrosenb]

Should I use 3 1/2 pvc or stick with the 4in pvc that I have? I didn’t realize 3 1/2 pvc is an option

 

[Reach4]

What are you replacing? The piping above all of the way to the roof, or are you bridging a gap and keeping the cast iron on each end of the gap?

 

[Jeff H Young]

sorry that measurement screwed me up I thought you had 4.027 but you are 4.270 so your od is pretty big .
i dont know exactly what your doing just replacing a section of pipe and no fittings are involved . if its just a vent should be fine drain pipes shouldnt just change size as the waste wont flow properly but i guess the easy answer is scrowl through the info Terry gave you and order your bands.

 

[Mrosenb]

I want to replace a section of the main stack. The galvanized sink vent is too low and broke off at the threads and the bend under the toilet is starting to rust through. I got the cast secured and cut out the section. I was planning on using 4in pvc and making new sink and toilet connections.

 

[John Gayewski]

No such thing as 3.5" cast iron pipe.

 

[wwhitney]

I am thinking 3005-33 on top of 3 inch PVC to upper cast iron.

-33 is not going to work, that's 3.5" ID on each side.

I think 3000-43 for connection to 3" PVC when appropriate, and 3000-44 for connection to 4" PVC when appropriate.

As to the ID issue, I have no idea. A picture of the inside might help, is there a chance that rust buildup could account for some of the discrepancy?

Cheers, Wayne

 

[Reach4]

-33 is not going to work, that's 3.5" ID on each side.

He said "I have outside diameter 3.58in" so I was thinking that was the OD of the upper pipe, and the lower pipe was a bigger OD.

Looking at the photo more clearly, I now see was measuring ID.

 

[wwhitney]

He said "I have outside diameter 3.58in"

Yeah, typo in the OP, the first instance of outside diameter should be inside diameter.

Cheers, Wayne

 

[Mrosenb]

Thanks. I must have been measuring a lump on the inside. I took another measurement and it was fine. This is just me worrying about every detail. I’ll share photos of the new plumbing when I get it dry fitted.