Fixing old cast-iron waste pipe with extensive rust & hairline cracks


Our cast iron waste line dates back to 1895!!!! We have replaced all the waste lines in the house with new PVC except for the short stub that goes through the foundation wall (and continues out deep underneath our yard to the street main sewer pipe).
However, the stub which consists of about 1 foot of cast iron pipe and a cast iron hub has extensive rust on the inside along with some visible on the outside. There also appears to be at least one hairline crack running through the hub with some evidence of (minor) past leakage. During our 4 years of owning the house, we haven't seen any leakage (or blockages for that matter).
Due to the expense of excavating the yard, we would like to avoid replacing the pipe for as long as possible. I know that some firms can put an epoxy condom in the pipe but that also is not cheap.
Is there any stop-gap way to "strengthen" the pipe to prevent it from cracking (or leaking further)? Can anything be done to minimize or impede further rusting?
I was thinking of something like: - Use a steel brush (or wheel) to remove the exterior rust and help identify location of hairline cracks. - Fill cracks (and other suspect areas) with JB Weld expoxy. - Spray on Rustoleum primer for heavy-rusted metal - Spray on topcoat of white paint (mostly cosmetic here)
Will the above work/help to prolong the life of the remaining cast iron pipe and lessen the risk of a more catastrophic crack developing out of the hairline crack?
Any other suggestions?
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If it aint broke, don't fix it. In fact the more you putz with it, the more likely something will happen. If the hairline crack does start to leak, you can try JB Weld or similiar.
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snipped-for-privacy@invalid.com writes:

I did pretty much the above. Actually after using a wire wheel chucked in my drill, the exterior of the pipe cleaned up really nice with much less rust or pitting than I had expected - looks like new except for a single hairline crack running from the hub back down the pipe about 6 inches.
I then sanded, cleaned with alcahol and applied a wide thin bead of JB Weld. I covered with several coats of Rustoleum "Heavy Rust" primer (it's what I had around) and topcoated with some almond spray paint (matched what was on the rest of the pipe).
So far looks good and hopefully will be some added insurance against spreading of the crack or leaking in the future.
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I'd either replace it or not touch it. That casting may fall apart once you take a power tool to it and start removing the clumps of oxidation that are holding it together. My vote would be the liner.
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If it's 4" and a fairly straight run, you can drive 3" pvc through it. how far to the street?
s

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Running 3" through it, if it's 4" or larger will work as I have done it before.
Also those large rubber flexible gaskets, often used for pipe joins, with 2 pipe clamps on either end will remedy a hair line crack.
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Definitely a case for Marine Epoxy.
Just wrap the entire stub with about 2 pounds of the stuff and it will seal the pipe and last for eternity. If the cast iron crumbles from the rust, the epoxy shell will contain all the waste.

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