1989 cast iron splitting along the length - why

[MPdesign]

On a 1989 large apartment building with a basement, many horizontal sections in the basement are split along the length.

The property, and the properties regular plumbing vendor were unaware of the problem because there is actually only a small amount of leaks from the cracks.

I see cast iron all the time and it usually lasts forever, any idea what may be causing the failure?

On an aside, I am calling for replacement of all accessible cast iron, camera inspections, etc.

Thank you!

[Jerry Simon]

On a 1989 large apartment building with a basement, many horizontal sections in the basement are split along the length.

The property, and the properties regular plumbing vendor were unaware of the problem because there is actually only a small amount of leaks from the cracks.

I see cast iron all the time and it usually lasts forever, any idea what may be causing the failure?

On an aside, I am calling for replacement of all accessible cast iron, camera inspections, etc.

Thank you!

I always thought those were weak spots in the lines that split-open when hot water ran through the lines, then cold water; expansion, contraction = stress cracks. Right or wrong, I know what you mean, and I see it quite often.

[MPdesign]

I always thought those were weak spots in the lines that split-open when hot water ran through the lines, then cold water; expansion, contraction = stress cracks. Right or wrong, I know what you mean, and I see it quite often.

Ah, that makes perfect sense. in your experience, does this normally happen to the verticals as well as the horizontals? I ask because the hot/cold should be more focused to a single area in the horizontals.

[Jerry Simon]

I always thought those were weak spots in the lines that split-open when hot water ran through the lines, then cold water; expansion, contraction = stress cracks. Right or wrong, I know what you mean, and I see it quite often.

Ah, that makes perfect sense. in your experience, does this normally happen to the verticals as well as the horizontals? I ask because the hot/cold should be more focused to a single area in the horizontals.

I actually see it more with riser pipes. With laterals, water can sit in the pipe and temper the water, so the temperature changes aren't as dramatic as they could be with hot water flowing down a riser pipe, then cold flowing down same.

[kurt]

There are dramatic differences in quality with iron components. I'm not entirely sure why. I see mountains of cast all the time (like Simon). I own properties full of cast, my stuff is all "fine", albeit with interior deposits and rust.

When I see iron go bad, which isn't that often, it's deterioration from the inside out; it rust, delaminates, and the delam process is what blows it apart.

I don't know about that thermal expansion/contraction theory; I don't think so. I think it's bad iron. Maybe I'm wrong.

There was a lot of bad iron pipe post WWII. Again, don't know why, but when I find bad stuff, it often dates back to that time.

I see vent pipes go bad way more than Drain and Waste.

[mjr6550]

I have seen this many times and age is not necessarily a factor. It is usually at the top of horizontal runs. I think that the mixture of air and moisture at the top of the pipe causes more corrosion there and when the pipe weakens enough stress in the pipe causes the crack. This is just a theory, so maybe I am totally wrong.

[kurt]

I think you're right. It's usually along the top. Although, I see them along the sides too.

I still think its largely quality of material. My building is 100 years old, and the stuff is as hard and rings like new steel when you tap it. Newer stuff kind of thuds.

[Bill Kibbel]

http://www.oldhouseweb.com/how-to-advic ... ipes.shtml

[Mike Lamb]

I always thought those were weak spots in the lines that split-open when hot water ran through the lines, then cold water; expansion, contraction = stress cracks. Right or wrong, I know what you mean, and I see it quite often.

Ah, that makes perfect sense. in your experience, does this normally happen to the verticals as well as the horizontals? I ask because the hot/cold should be more focused to a single area in the horizontals.

I actually see it more with riser pipes. With laterals, water can sit in the pipe and temper the water, so the temperature changes aren't as dramatic as they could be with hot water flowing down a riser pipe, then cold flowing down same.

Like what Jerry says, vertical pipes rot out first. And you usually can't see it unless the walls are gutted but there is usually water and gas leakage from the vertical in 70+ yr buildings. Rotted cast iron pipe.

[kurt]

It's true about the vertical vents; pretty common. When we cut them out, the walls are definitely thinner material, so it makes sense they'd fail first.

OTOH, when I opened up the walls in the apartment building to do some work, all the cast was in excellent condition. We tapped into some of it in a plumbing alteration, and it's all clean and relatively unmarked without any significant corrosion. 100 year old cast.

Anyone else see varying quality in cast?

It's just a theory, but I notice it in old steel vs. new especially with lintels. The old stuff was way better, much more corrosion resistant.

[ghentjr]

Our condo is in a 12 story Florida east coast building built in 1980. The vertical stacks have been failing over the last 4 or 5 years causing walls to be opened and full runs replaced. The theory is that it is cast from Korea but no answer to why it is cracking and falling apart. Some of the failed sections look new.

[Rob Amaral]

http://www.oldhouseweb.com/how-to-advic ... ipes.shtml

Exactly my thoughts..

[mlparham]

http://www.oldhouseweb.com/how-to-advic ... ipes.shtml

That's an interesting article but I don't understand how a seam created in the casting process can cause this problem unless it was standard procedure to install the drain line with the seam up. I find it hard to believe that a plumber would take the time to locate a seam then install the pipe with the seam up.

[Marc]

http://www.oldhouseweb.com/how-to-advic ... ipes.shtml

That's an interesting article but I don't understand how a seam created in the casting process can cause this problem unless it was standard procedure to install the drain line with the seam up. I find it hard to believe that a plumber would take the time to locate a seam then install the pipe with the seam up.

I don't think that's what Bill is saying. He's saying common locations of linear cracks along the length of the pipe are at the seam or at the top of horizontal runs (because the corrosive gases are there).

Marc

[mlparham]

Here is a link to a forensic metallurgical analysis of horizontal cracking in cast iron drain lines.

Cast Iron Pipe Investigation"]Cast Iron Pipe[/url]

[Marc]

They coulda just read this thread, called Kurt and Bill, and gotten the same result while saving a bundle.

Marc

[Jim Katen]

Slightly off topic:

Perhaps my understanding of cast iron is flawed, but I thought that the pipes didn't have seams. The forms would. But isn't cast iron "cast"?

[mjr6550]

The cast iron does not have a seam, but if the mold if slightly offset, then this could create a stress concentration in the cast iron.

[kurt]

So, if I'm reading this right, failures are caused by residual stress, corrosion induced hoop stress, microstructure variance (which seems to be sulphur compounds in the iron), and installation deficiencies that increase stress.

I'm betting those microstructure variances are a main issue. All I do is look at cast all day, and some of it's just fine, and a little bit of it is not. The stresses....I'm not so sure that's all that big of a deal. I see major amounts of poorly supported or unsupported iron that's a century old that's doing fine.

I think how well the system is vented plays a big part. If the corrosive gas can't linger in the pipe, it's going to alleviate a lot of issues.

[mlparham]

Slightly off topic:

Perhaps my understanding of cast iron is flawed, but I thought that the pipes didn't have seams. The forms would. But isn't cast iron "cast"?

A seam, sometimes referred to as a scar, is a metallurgical defect in cast products.

[David Meiland]

It's easy to imagine the molds getting slightly misaligned during the production process and producing batches that have visible seams. I have seen at least one plumber grind the pipe a bit where his no-hub fitting is going to go, to remove a slight ridge.

Cast iron pipe is an out-the-door product--they make it and it gets installed. Cast iron machine parts, at least the better ones, and left sitting around in piles for a while before they start machining them. If you make a tablesaw table out of a green casting, it's likely to warp.

[kurt]

How serious is a scar? Does it have a different structure, or is it a just a scar?

I keep going back to this "quality of pipe" thing. Chicago's all cast if it's <25 years old. All of it. I still see brand new cast in larger buildings. I see huge variations in the quality of the pipe finish, hub structure, interior finish, and they "ring" differently when I tap them with my brass hammer.

Lots of it is unsupported. I see stacks that are kinked out of plumb 10deg or more from the stack weight alone, and yet no problems. Entire runs of unsupported iron that don't have any defects inside or out. I wonder how significant hoop stress is.

I'm now thinking this idea of how well a system is ventilated could play a large part. If the air is constantly moving and venting out of the system, the corrosive nature of the gas has to be minimized to the point of insignificance. I'm now remembering some of the failures we uncover had issues with the general building sewer, backups or the catch basin (grease trap) was clogged and nondraining....all resulting in sewer gas remaining in the pipes.

[ghentjr]

I'm now thinking this idea of how well a system is ventilated could play a large part. If the air is constantly moving and venting out of the system, the corrosive nature of the gas has to be minimized to the point of insignificance. I'm now remembering some of the failures we uncover had issues with the general building sewer, backups or the catch basin (grease trap) was clogged and nondraining....all resulting in sewer gas remaining in the pipes.

The failures in our building start at the highest floor. Ocean front with constant breezes. Condo building with no special chemicals or gas. ( Unless you consider burritos on Friday early bird. )

[kurt]

Yeah, I see most failures in the 2" vertical vents @ upper floors. It seems like thinner pipe wall in those vents. There's the possibility that the gas concentrates up in the higher areas, condenses, and the corrosive aspect is intensified.

Does that make any sense?

I've thought about this for years. Why does some of it fail but most of it works fine?

[mlparham]

The significance of a seam depends on the depth of the seam and the end use of the cast product. For example, seams often occur on convex surfaces of cast products.

If the seam occurs on the exterior surface of a non pressurized drain pipe does it matter? It depends on the depth and cause of the seam, which can only be determined by metallurgical analysis.

If you really wish to get deep into the different types of cast iron, how they are processed and their applications, click here.