Can anyone enlighten me on why a vertical cast iron stack would crack? I have one section of pipe that cracked about 4 feet vertically in an interior wall... and I think I have another big crack in another wall.

I guess the obvious answer is rust... or extremely hot water in a cold pipe?

I'm replacing the first 4' section tonight, but I'm concerned that, depending on the reason behind the crack, I may find myself replacing the entire stack in that wall.

Ideas?

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Originally Posted by deanrinehart

Can anyone enlighten me on why a vertical cast iron stack would crack? I have one section of pipe that cracked about 4 feet vertically in an interior wall...and I think I have another big crack in another wall.

I guess the obvious answer is rust...or extremely hot water in a cold pipe?

I'm replacing the first 4' section tonight, but I'm concerned that, depending on the reason behind the crack, I may find myself replacing the entire stack in that wall.

Ideas?

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Is it old hub and spigot pipe, or is it newer no-hub pipe?

Pipe was installed around 1927, my relatively new experience tells me it's bald and bell (is that hub and spigot?).

Also... I'm making the assumption that the only repair for a crack this length... almost the full section of pipe itself... is replacement, correct? At its widest it's about 3/16 inch.

The pipe is supported by bells above and below, so I'm planning on cutting about 4-6" from each end and putting bands around with PVC in between. The bells on both ends should be all the support the pipe needs.

I've never heard of the older, heavier cast iron cracking like that before, especially along the full length.

I have seen it happen with newer cast iron, though.

Usually because the chain on the snap cutter was rounded over and crushed the pipe instead of cutting it.

Oh... and I have to assume that, given the possible compromised ends of this pipe, cutting with a pipe cutter is preferred over the relatively violent sawzall method...

I'll grab some pictures tonight and post. My father, who was a plumbers apprentice way back, is also a bit perplexed. Given that we may be seeing this elsewhere in this house, we were thinking bad batch of pipe, but the tool theory works as well.

Given that we're talking about 2 odd compromises visible in a house with 5 separate stacks running about 28' vertical each... I may be in for a fun summer.

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Originally Posted by deanrinehart

I'll grab some pictures tonight and post. My father, who was a plumbers apprentice way back, is also a bit perplexed. Given that we may be seeing this elsewhere in this house, we were thinking bad batch of pipe, but the tool theory works as well.

Given that we're talking about 2 odd compromises visible in a house with 5 separate stacks running about 28' vertical each...I may be in for a fun summer.

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The pipe manufactured in the twenties was some pretty thick, tough stuff.

And then it went all to heck during WWII (thinner walled and shallower hubbed), and stayed that way during the housing boom immediately following the war.

Just as they were starting to cast some decent pipe again, ABS and Copper came along and stole it's thunder.

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Originally Posted by deanrinehart

Oh...and I have to assume that, given the possible compromised ends of this pipe, cutting with a pipe cutter is preferred over the relatively violent sawzall method...

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If you rent a chain cutter, try to find one of the smaller cutters manufactured by Reed, they are much lighter and less likely to knock you off a ladder when cutting overhead.

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Originally Posted by iamgrowler

The pipe manufactured in the twenties was some pretty thick, tough stuff.

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There is a chance that this is the thinner pipe. The wall behind the pipe... a flight of stairs and a store room... looks to be a different, newer type of metal lath. This may be a post WWII replacement.

Great.

I would not use a chain cutter on old cast iron pipe that is breaking down. I use a lenox blade 656r or the 8 inch, on slow speed. Keep the foot of the sawzall hard against the pipe the whole time. It will amaze you how fast and clean this blade cuts old or new cast iron. The chain cutter will crush one side and will no longer be able to cleanly cut it.
That lenox blade is a wood blade, but trust me on this one.