Heat transfer in pipe?

[StructureMan44]

Please bear with me, I have a structural background. If we are heating one end of an 18"Ø schedule 160 pipe to 225°F is there an equation that states the length of pipe until the heat dissipates and the pipe is back at the ambient temperature of 70°F? I imagine along the length of pipe it'll fall quickly to ambient temperature, maybe 6in away it is 200°F, 1ft at 150°F, 2ft at 100°F. Is there an equation that approximates this behavior and tells the length needed to return to ambient?

 

[IRstuff]

Please refrain from double posting. If you want to save your other thread's content, you should ask the management to move the contents here

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[FredRosse]

No simple answers here, and the answer s very dependent on the fluid within the pipe, and its orientation (vertical / horizontal / sloped, etc.) plus heat flow up or down, ambient surroundings, wind or local turbulence, etc.

We have evaluated many transients of this sort in power plant practice, and much analysis is required to get realistic answers. Simple calculation approach often gives answers that are one or more orders of magnitude (factors of ten) in error.