Pipe diameter expansion due to temperature increase

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Discussion Overview

The discussion revolves around the thermal expansion of a stainless steel pipe due to an increase in temperature, specifically focusing on calculating the increase in outer diameter and wall thickness as the temperature of water within the pipe rises by 10 degrees Celsius. The context is experimental results from a flow loop, and participants are exploring the relevant calculations and concepts in thermodynamics.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant seeks to understand the increase in pipe dimensions due to temperature change, indicating a lack of expertise in thermodynamics.
  • Another participant suggests that the calculation involves multiplying the coefficient of thermal expansion by the relevant dimension and temperature change, but does not clarify the distinction between length and diameter.
  • A participant questions the initial suggestion regarding the relevance of the pipe length in calculating diameter expansion, seeking clarification on terminology.
  • Concerns are raised about the accuracy of a participant's calculations, specifically regarding the multiplication of thermal expansion coefficients and temperature changes.
  • Participants express a need for resources, with one asking for a reputable book on the topic of pipe diameter changes due to temperature variations.

Areas of Agreement / Disagreement

Participants exhibit some confusion regarding the terminology and calculations related to thermal expansion, with no consensus reached on the correct approach or calculations. Disagreements arise over the interpretation of dimensions and the accuracy of calculations presented.

Contextual Notes

There are unresolved assumptions regarding the application of thermal expansion principles, and the discussion reflects varying levels of understanding among participants. The specific conditions of the experimental setup may also influence the calculations, but these are not fully explored.

doop4
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Hi

Firstly, this is not a homework problem. It's regarding some flow experimental results I have and to understand the results further I am trying to identify possible reasons for the patterns I see. I don't have expertise in thermodynamics hence finding the following problem a bit puzzling. Any help and pointers would be most appreciated.

I have a 60mm OD stainless steel pipe with a wall thickness of 2.5mm I'd like to calculate the increase in both these values as the temperature of water within the pipe increases by 10 deg C. The straight length of the pipe is 4m and it is part of a complicated flow loop so therefore some approximations will need to be made.

How would I go about calculating the increase in the pipe OD and wall thickness as a result this change in temperature? Thanks in advance for your help!
 
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It is a straightforward calculation multiplying coefficient of thermal expansion by length (of whatever dimension) and temperature change. Give it a try and we'll check your answers...
 
russ_watters said:
It is a straightforward calculation multiplying coefficient of thermal expansion by length (of whatever dimension) and temperature change. Give it a try and we'll check your answers...

Thanks for your reply! Why should the length of the pipe matter when I am after the expansion in diameter of the pipe? Did you mean diameter instead of length? Puzzled but I'll have a go assuming that you meant to say diameter. Forgive me for being dim! :(

thermal expansion=6.5e-6 (for stainless steel)
temp change= 50F
D=60mm (0.197ft)

So

expansion= 6.5e-6 x 0.197 x 50= 0.06ft ~ 18mm?

That sounds horribly wrong. I think I've misunderstood what you've said. Any help will be much appreciated!

P.S: Could you recommend a reputable book which has changes in pipe diameter as a result of varying temperature?
 
doop4 said:
Why should the length of the pipe matter when I am after the expansion in diameter of the pipe? Did you mean diameter instead of length?

The diameter is also a length (as is the radius, wall thickness, etc.). They all have units of distance, and they'll all expand linearly with temperature if unconstrained. It's just a confusing part of the terminology that the word is the same as the word that describes the distance of the longest extent of the pipe (the pipe length).

doop4 said:
expansion= 6.5e-6 x 0.197 x 50= 0.06ft ~ 18mm?

Whoa, check your calculations. How can multiplying a number in the parts per million by ten give you 0.06?

doop4 said:
P.S: Could you recommend a reputable book which has changes in pipe diameter as a result of varying temperature?

It's not a book, but http://www.engineeringtoolbox.com/thermal-expansion-pipes-d_283.html" might get you started.
 
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