Fire Damage to Ductile Iron Pipe 3

[trevor2000]

Has anyone heard of delaminating of the cement lining on DI pipe as a result of fire damage?

 

[cvg]

very likely since the metal pipe and the cement mortar lining expand at different rates when heated. the mortar is not very flexible.

 

[rconner]

I believe it would depend on the specific heat and duration of the fire, how tight and well compacted is the lining, and probably many other factors. Is this a sort of hypothetical question, or has some sort of piping system actually been put through a fire with or without water in the pipe?
I believe virtually any substance or piping material can be affected with sufficient application of heat!

 

[bimr]

It is reasonable to predict that the lining will fail. A fire produces much higher temperatures than the cement coating was designed to handle. Cement lining is satisfactory for temperatures only up to 212°F. If asphaltic seal coat is furnished, the lining is only adequate for temperatures up to 150°F. Some of the cities with underground steam piping systems have experienced ductile iron lining failures because of the temperatures that the piping is exposed to.

Ductile iron piping is FM listed only for underground fire services. Exposed ductile iron piping will not handle the pipe stress caused by the temperature difference in a fire. The gaskets will fail at 300 Degrees C. The fittings will fail because of the pipe stress caused by the temperature.

Ductile iron has a relatively low melting point of 2100 Deg F. Steel has a melting point of 2700 Deg F. A fire flashover occurs at about 1000 Deg F.

 

[trevor2000]

Thanks bimr. In this case, the DI pipe was exposed to a structural fire. I'm not sure if a visual inspection will be adequate to determine if the DI pipe should still be used as a water main.

 

[dicksewerrat]

I would guess that the cement lining was popped off by the heat. The gaskets are probably also toast. Cut a few pipes in different areas and inspect.

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[rconner]

I agree with some good points made in these posts but I feel compelled to elaborate a little more on my earlier response. As I stated, sufficiently high heat for a prerequisite amount of time will indeed damage just about anything; however, I am also aware that consolidated cement linings in ductile iron pipe can also often tolerate a considerable/perhaps some surprising heat application before spalling out. In this regard, it is occasionally necessary to remove and/or replace some previously applied cementlinings in factory settings. A couple methods that have been utilized for many years to accomplish this are passage of the pipes through extremely high temperature annealing ovens, or considerable full-length gas flame direct impingment on the outside of an empty pipe in rotators. In many cases readily observed in the gas flame method, the pipe must be heated to near red-hot temperature to remove all the lining. I believe "red-hot" pipe temperature is in turn basically in excess of a thousand degrees F. or more. It is also quite common to arc weld on cement mortar lined ductile iron as well as steel pipe (with at least localized temperature considerably higher than that) without significant damage to the linings. I would therefore not necessarily equate a much lower (normally adequately conservative) maximum "temperature rating" that a manufacturer or professional association allows forlong-term service of all elements of a working piping system with potential surviveability with reasonable intactness of an empty or flowing pipeline, or pieces of pipe in storage, in an accidental fire environment (of what one would at least hope would normally be much shorter duration).

Ductile iron pipes, and gray cast iron pressure pipes furnished before them in the USA and up until the late 1970's, are in a sense literally born of heat and fire, and I guess I was somewhat surprised to see much singling out concern of heat on the piping material per se (after all, iron has long been a traditional material e.g used for wood-burning stoves and frying pans etc.!) While I have only been in the industry for 35 years, I was likewise also not aware that there was promotion at least in any recent era in the USA of cementlined ductile iron pipes specifically for "steam service" (though I guess I would also not necessarily surprised if it is being used somewhere). I am aware however that for many decades ductile iron has however been rather exclusively specified for some specific and otherwise potentially problematic scum etc. lines e.g. in wastewater treatment plants, that might be subject to "steam cleaning" (should that ever be necessary in the future to remove clogs), although I think instead of cement mortar lining many of these quite special lines have been and are specified with special glasslining, that reportedly has greater lubricity than any common plastics or polymeric linings, and adequately chosen temperature gaskets. Contrary it would appear to perhaps some inference of this thread, ductile iron is rather exclusively specified for such services, due to its proven performance and its tolerance for heat, to allow for the extremely high temperature firing of the glasslining on the inner pipe wall, and also effects of potential future steam cleaning.

I think Mr. Cornelius has made a good suggestion, i.e. to take look at the linings etc. by whatever means available and see what they actually look like after the event. If this is a water pipeline instead of pipe stacked in some sort of storage structure, perhaps it may also be possible/make sense to look at any other components as well, and maybe even run a new hydrostatic test at greater than working pressure to get a better feel also for present gasket/joint integrity. If all else is OK, perhaps any damaged gaskets might be readily replaced with some common joints of exposed ductile iron piping ?

Now, all this being said, if you choose to not coninue to utilize the piping for whatever reason, I suspect it might
well (unlike many other types of pipe, or other relics of fires) still bring top dollar from even your local scrap dealer.

 

[bimr]

Regarding "While I have only been in the industry for 35 years, I was likewise also not aware that there was promotion at least in any recent era in the USA of cementlined ductile iron pipes specifically for "steam service" (though I guess I would also not necessarily surprised if it is being used somewhere)."

This was referring to underground piping located adjacent to steam piping and experiencing the heat from adjacent steam piping.

Some additional reports and references:

http://nepis.epa.gov/EPA/html/DLwait.htm?url=/Adobe/PDF/P1004Q38.PDF

http://www.dipra.org/pdf/cementMortarLinings.pdf

 

[hokie66]

I would think the answer would vary, depending on whether the pipe was full or not, and also how long the structural fire lasted. Only by inspection will you really know.

 

[rconner]

Hi bimr,
I am aware of the conservative service temperature document of DIPRA, but I was unable to open whatever the other document (as you say apparently some issue or concern of proximity of piping to hgih temperature steam lines?)is. Do you have another link (e.g. to html etc.), or could you at least provide the copy of the paper etc.? [I do understand some at least concern in general on the part of authorities, as I do remember a very problematic burst of a sizeable pvc waterline in proximity to a steam line in the Midwest several years ago.]

 

[cvg]

the link worked for me, here is the title:

Condition Assessment of Ferrous Water
Transmission and Distribution Systems
STATE OF TECHNOLOGY REVIEW REPORT
EPA/600/R-09/055 | June 2009 |

http://www.epa.gov/ord

Office of Research and Development
National Risk Management Research Laboratory - Water Supply and Water Resources Division

 

[rconner]

Thanks, cvg
[I was able to go to site at link you provided, then readily access the paper with a keyword search -- I guess problem could be my caveman computer! In quick scan I could not find however a specific citation re steam, but will look in more detail when I get a chance.]