"Historic Integrity" is the only reason I can think of using lead to do anything except weigh things down or block radiation. Perhaps a letter to "Ask TOH" is in order?

I had a section of cast iron replaced with PVC a couple of weeks ago. The cast iron hub into which the PVC was ended was sealed with oakum & lead.

I wouldn't be surprised if there is some other kind of sealer, but, remember, that has to get past the union and local code.

On the other hand, oakum & lead are probably cheaper than a high tech sealant and don't require retraining. Also, what is its proven life? While oakum & lead can leak, I'd being willing to bet there are plenty of lead 100 year joints leak-free and in use to this day. I know it's not the same, but I've spent enough over the years on "high-tech 20 year" caulk that lasts anything but 20 years.

This post was edited by DreamingoftheUP on Tue, Feb 25, 14 at 19:37

There is no reason to use lead when repairing /replacing cast iron pipe. Long before cast was replaced with pvc in new construction,the hubs had a rubber seal that snapped togeather. Most repairs I have seen over the last 20 years was made useing a rubber sleeve with worm gear clamps.

I can see that when joining similar-sized lines, a sleeve is the only way to go. (I've used Dresser couplings to mend schedule 80 steel pipe.) But on the TOH segment, they were joining PVC to the 'bell' end of the original cast iron drain line at the basement wall. While I have made custom-curved PVC pipe by heating it up in the oven - very carefully - pouring molten lead into the joint seemed, well, risky. The narrator cautioned that they didn't touch it again for several hours, letting the PVC regain its rigidity.

The thing about lead and oakum joins is that the lead is used to secure the oakum. The lead does not make the joint. If you look into the bell end of the CI you will see a recess inside the lip. When you pour the joint with lead you then take inside and outside yarning irons and you basically set the lead int othe recess and against the pipe. once the oakum begins to get wet it will swell and that is actually what mass the joint.

I like the Mission band brand of couplings. that said, if I am working to two fixed points with a single piece I will get a no-hub coupling that I can pull the clamp and outer support back, affix the rubber coupling to one end of the pipe and fold it back on itself. Position the pipe and roll the band back over the new pipe, whether CI, or PvC. Your dimension has to be spot on, but I've done a lot o them. Also, if you are going CI to PVC/ABS they make special claps for that.

Interesting discussion. Don't know why they used lead in my case. The run that was cut out was steel on the top and terminated into cast iron. At the top, a flexible coupling was used with clamps.

At the bottom, where the leak was, lead was used. And this wasn't some old timer doing a side job for me. The plumber was probably in his late 20's to early 30's from a reputable plumbing contractor.

Looks like a good job to me. He set the lead into the joint. You can see the marks left by his yearning irons.

Part of the TOH segment was the plumber following up with yearning irons several hours later. That joint was a vertical one, in which a flexible "pipe runner" was wrapped around the PVC pipe to retain the molten lead while it was poured in at the top. With the horizontal joint pictured above, it would seem easy to fill the joint adequately, yet it still failed, even after "yearning."

My experience with casting lead is limited to making .44" round balls and various fishing sinkers, but I now understand that yearning is to physically deform the lead joint to better grip the cast iron hub. Yet there is little 'grip' on the PVC which could be deformed/softened by the molten lead. I could see how this could be an issue if the plumber didn't bother with coming back a couple of hours later, rather hammering away as soon as the lead solidified.

Yarning irons are used to pack the oakum. Caulking irons are used to tamp the lead after it cools. PVC adapters are available with a narrow flange to permit better packing of the oakum.
I prefer to use the Fernco "donuts" for the transition.
http://www.fernco.com/plumbing/donuts-o-rings/donuts

Here is a link that might be useful: Adapter

"I prefer to use the Fernco "donuts" for the transition"

So do the majority of plumbers who want customers to get the best options.
600+deg F lead in contact with pvc can't help but damage it.

Thanks...I was going to ask about the origin of that term, but "yarning" I can understand. My experience with oakum is limited to wood planking on old sailboats. But instead of tar or pitch, we used 3M 5200.

Perhaps you have heard the term "...the devil to pay." That refers to the lowest hull plank on a ship; before drydocks or marine railways were commonly available, vessels would be grounded at high tide, with people starting to work as the tide went out. The lowest planking joints were the hardest to "pay" that is, insert the oakum and pitch, before the tide started coming back in.

Cheers