Cast Iron DWV Exposed to heat from fire

[Dylan Whitehead]

Does anyone have any sort of code referance regarding that CI pipe should be replaced when exposed to fire? Water test on pipe showed leaks just curious if there is anything stated out there.

[Scott Patterson]

Does anyone have any sort of code referance regarding that CI pipe should be replaced when exposed to fire? Water test on pipe showed leaks just curious if there is anything stated out there.

Code will not address the performance of an item like that.

Heck, if it's leaking ya don't need a code or for that matter anyone of anything else to tell you it needs replacing..... :D

Leaks could be from a fracture in the pipe or from the dried out oakum/seals around joints. I have seen a fire cause both with cast iron pipe.

[Dylan Whitehead]

I have been asked to give a statement on this and I told them the only thing I can give without seeing any of the tests performed myself is something along the lines of " Heat from a fire could cause damage to cast iron piping."
I am not going to say anything more than that there is a possability of the fire causing damage.

[Scott Patterson]

I would think it would have to be a hell of a fire to crack cast iron pipe. Aren't woodstoves made of that stuff? Molten lead is used to secure the joints, that would almost definitely melt away, followed shortly by the oakum burning up.

Most house fires are pretty dang hot! Also, you are most likely talking about 50 or so year old pipe that already is at the end of its useful life. Cast iron pipe gets pretty thin from rusting away over the years.

[Scott Patterson]

I have been asked to give a statement on this and I told them the only thing I can give without seeing any of the tests performed myself is something along the lines of " Heat from a fire could cause damage to cast iron piping."
I am not going to say anything more than that there is a possability of the fire causing damage.

Is this a house you inspected for a buyer?

[Jerry Peck]

I would think it would have to be a hell of a fire to crack cast iron pipe. Aren't woodstoves made of that stuff? Molten lead is used to secure the joints, that would almost definitely melt away, followed shortly by the oakum burning up.


It does not take a lot to crack cast iron pipe. Most of it is lower quality from overseas, mainly China, and it is not uncommon for it to be cracked before being installed, or get cracked being installed. The newer cast iron I've inspected in high-rise buildings just ain't like the cast iron of old. Even when the plumbers lay it down on the concrete decks a little too hard, you will hear it crack, tap it with a hammer handle or screw driver handle and you will hear the difference if you are close to the crack.

Besides, few are using hub-type cast iron, most new stuff is hubless and joined together by those rubber banded fittings discussed on another thread a few months back.

Have a fire and those will go first, sagging, leaking, melting, burning, etc., but the pipe will not fall as it is (is supposed to be, anyway) supported and secured in place.

[Jim Zborowski]

Things to consider with cast iron pipe:

Flaws in manufacturing causing a weak spot, thereby making it more
suseptible to cracking

Erosion ( rusting ) from the inside causing a thinner area in the pipe,
making it more likely to crack

Pipe being exposed to unusually high tempuratures folllowed by rapid
cooling, possibly from water used to extinguish the fire, causing fracture
due to thermal shock

Cheap pipe ( as in made in china ) has a tendancy to contain impurities
causing weak spots

[Dylan Whitehead]

Scott this is a house that was built in 1930. It caught on fire this year because it was struck by lightning. To answer your question no this is not for a buyer or seller, the plumbing company that was hired to do the repairs took it upon themselves to take out all the old cast iron pipe before discussing it with the insurance company. They said that they put a water test on it and found leaks, I am the inspector for the city and was never called to confirm this. Now they want my help in stating that the cast iron should of been replaced.

Like I said before in the previous post I told them without seeing any of their tests myself, I could not and will not say either way that the cast iron should of been replaced. I will say that the possibility is there that the cast iron could of been damaged.

[Jerry Peck]

Dylan,

Now knowing your position in this and what is being asked, I would address it this way:

Tell the plumber to call the local plumbing supply house, have them contact the manufacturer of the cast iron pipe they carry (unless the plumber knows the manufacturer of the pipe they removed) and have the manufacturer send a letter regarding their position in their cast iron in fire condition and their stance on whether or not it needs to be replaced after a fire.

That letter will now set the precedent for all future repair work regarding cast iron in your area.

Short of 'replacing it because it needs to be replaced after a fire per the manufacturer', proving that 'it needed replacing because it leaked' is up to the plumber.

As the local inspector, remember, *all* the following needs to be replaced:
- gypsum board which was effected by the fire (heat, smoke, water)
- fire stopping material which were effected by the fire (heat, possibly water stream)
- electrical which was affected by the fire (wetted down by the fire fighters, water stream, conduits filled with water with conductors not designed, listed or labeled to be direct burial or submerged in water)
- insulation which was effected by the fire (smoke, water)
- there are other items, that is just a start