Steam pipe from 0 to 301 Celsius...what happens?

[Saver2008]

Hi everybody!!!

I have a carbon steel pipe that will be used to transport SUPERHEATED STEAM. This will be used just for some situations (for a flare stack that when it flares it makes smoke and the intention of this steam is to get better the combustion and eliminate the smoke. So...this pipe line for steam will be used for this circunstances, not all the time. Some persons have told me that when you have a pipe line with no fluid and suddenly you put SUPERHEATED STEAM (a fluid very very hot and I mean hot as 300 celcius)the pipe line will "colapse" or it can be cracked or something like this. I do not what is the correct name for this phenomenon...can you tell me what is the correct name? Thermal cracking or something like this? And also, in order to prevent this, it is necessary to keep the carbon steel pipe line with a minimum quantity of steam in order to keep it HOT...is that really true?

Please help me with it.

Thank you very much
R

 

[IRstuff]

Thermal shock.

You can either keep it hot, or not attempt to instantaneously heat it. The stress comes from the temperature differential across the material in question. By limiting the temperature rise rate from the steam, the temperature is more equalized, and the material will not get shocked.

TTFN
faq731-376

 

[Saver2008]

@IRstuff thank you very much.

That`s it.

Thanks again!!!!

 

[MiketheEngineer]

BTW - it will expand somewhat - if it doesn't break. Take that into account

 

[chicopee]

Power piping ASME/NB code will list the grades of the carbon piping for superheated steam.

 

[chicopee]

Oops s/b ASME/ANSI

 

[SeanB]

Keep steam to the flare at all times. Many flare tips require this - center steam and ring steam.

 

[Saver2008]

Everybody:

Thank you very much. @ chicopee: where can I find it in ASME B31.1 to B31.8?
What do you think about it?
Someone told me that if I calculate the HEAT LOSS of all pipe line and then I use an equation like Q = U A dT where U is the thermal conductivity of material (for this case pipe) we can find the Q generated for making the THEMAL SCHOCK and I need to find other equation that I can use this energy and a dT in order to find out T2.....I think this is something "out of line" but what do you think?

 

[MrBTU]

I think a more appropriate equation is 13.36 EE-6 mm/mm deg C x (300-21.1 deg C) x length of pipe, and then analyse this growth and see what that does to the pipe - make sure the stresses do not exceed allowable, add hangers, bends, etc, as needed. The pipe itself, if properly designed, can handle the temp and pressure of the steam, it's the thermal expansion and the stresses that causes, that will be of concern.