Tapping into an old sewer line


Old 03-09-05, 11:54 AM
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Tapping into an old sewer line

My brother and I are both putting bathrooms in our basement. I am finishing my entire basement, but he is just doing a bathroom, so he is ahead of my schedule. Last week, we rented a pipe locator, found where the sewer runs under his slab (fortunately right below the desired bathroom location), jack-hammered/dug down to the pipe, and began preparing the pipe for the new connection. Don't worry, we won't connect until we have assembled the rest of the bathroom's DWV system.

The problem: The 50-year-old 4" cast iron sewer pipe is very corroded. We question how well the rubber coupler would seal to it. The surface is very rough and is as tough as concrete. We used an angle grinder to try to smooth out the surface, but the amount of dust was unbelievable and we didn't make great progress. We plan to build a tarp-tent around the area and then go at it with stiff wire power tool attachments, flexible sanding discs, and anything else we think might help us smooth out this sucker.

The Question: Is there a common solution to this problem? Are there tried and true methods that plumbers use? Is there some sort of coating that we could apply to the pipe that would smooth it out enough to make a seal that will last a lifetime?

My house is 20 years older than his, so I'm bracing myself for the same problem.

Oh, and one more question...there seems to be a "snap cutter camp" and a "carbide saw blade camp" when it comes to opinions about the best way to cut a cast iron pipe. Anybody swear to one method or the other?

Thanks for any advice you might have!
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Old 03-09-05, 12:24 PM
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Lots of things tried, don't know if any are true. If the surface is pitted, I would wipe a layer of silicone onto the pipe where the rubber seal is going onto it. Doesn't have to be real thick, just enough to fill the voids.
Snappers vs saw: The saw will give a straight cut with no chance of cracking the pipe. (unless it already has a hairline crack). It will also be time consuming and dusty as all get-out. Be real careful if you go this route. Blade hang-up and flying particles are dangerous.
I have always liked the hydraulic snappers. Most contractors use them for speed. Set the chain on the line you want, make sure it is straight, and pump the handle until it breaks the pipe. You can also get the long handled snappers. A bit of work but effective. May take two people on the handles. Any snappers leave the possibility of a cracked jagged cut. It's the cast iron, not the snappers. Good luck on your project.

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