Separating cast iron vent pipes


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Old 07-08-05, 04:30 PM
J
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Separating cast iron vent pipes

I'm taking out an 8 foot length of cast iron vent pipe. In this length there are two unions, and the sections seem to be held together by some black goop. I've cut through the bottom of the pipe and can move it back and forth about 2 inches, but not much up and down (it goes up and though a roof, where there seems to be more black goop). I'd like to separate the three sections and have tried hammering on the lip of one of the unions but it isn't even budging.

Can someone tell me the best way to take care of this? Should I take a sledge hammer and break them at the union (this would be hard to do, not much room) or is there a correct way to do this.

Any ideas would be appreciated.

John
 
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Old 07-08-05, 11:33 PM
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I have never heard of a cast iron union. Actually, I can't even imagine what you have unless it is galvanized pipe. The black goop may be some roofing cement to hide or stop a leak of some sort. I really need a picture of this line to tell you what you have. You can post pictures to a site such as Photobucket and then post A link to the pictures here. Good luck.
 
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Old 07-09-05, 02:19 AM
J
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Sorry, union was the wrong word...4 inch cast iron pipe has a flange on one end, into which the next piece of 4 inch cast iron pipe fits. This flange has some packing in it and some black tarry stuff. I ended up breaking the flange on the shortest piece and was able to loosen and separate everything. Unfortunately when I was up on the roof pulling the longest piece up through the flashing, I had forgotten to secure the lower piece and it fell out of the wall and hit the toilet tank and you can guess what happens when a 4 foot piece of cast iron hits a toilet tank.

If there is another way to separate the cast iron pipe I'd still like to know it, for the next time.

John
 
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Old 07-09-05, 08:50 AM
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Cast iron pipe is connected together with lead and okum. I am assuming that what you are calling a flange, is the bell end of the cast pipe. The next piece of pipe is placed inside the bell. This is called the spigot. Okum, which looks like horsehair with a sticky substance in it, is then wrapped around the pipe and pushed down into the joint and tapped in place with a hammer and special chisel. This makes a seal so the hot lead will stay in the bell. After the lead is poured and cooled, another special chisel is used to tap the lead around the bell to form a seal. Removing cast is never easy. Most people use a snapper tool to cut it. These can be rented. A reciprocating saw can also be used to cut the pipe. Good luck.
 
 

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