4 replies to this topic

[James-Zhou]

I'm trying to select proper tube for a high temperature heat exchanger ,the temperature of the tube would be about 950 degrees . can anybody offer some option of the tube material ,and the allowable stress of those tubes ? The code beside my hand can only offer allowable stress of tubes with the highest temperature of 700 degrees , which code do you resort to when you need to select pipes durable at over 900 degree ? Thank you very much !

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[T.S.MURALI]

First let us know the application.

you may browse through material properties -tensile ,impact,creep,rupture at such a temp.

steel/alloy steels upto 535 Deg c are available for continuous service.

what is the mean metal temp/tw ? you have to choose a material whose properties are suited for your application .consider tm ,tw for sure!

[T.S.MURALI]

It could be NI-cr based oxide dispersion strengthened alloy or cr-ta alloy. Please check UNSno 7754/MA754

These are used in furnace hot air application. in the range 700-900C temps. ,globally

You have to get the rupture,tensile,impact props and check for the appropriate standards/code compliance.

The metal life -rupture hours could be low -----10 k hours for metals like HR120 (at 900+ C)

Edited by T.S.MURALI, 12 November 2012 - 11:53 AM.

[James-Zhou]

T.S.MURALI,thank you for your answer .I am trying to design an air -air heat exchanger ,the hot air may pass through the tube side alone because of careless operation .So i just take the temperature of hot air as the mean metal temperature while choosing the pipe material .What i am caring about is if there is a code which can offer the allowable stress of some kinds of tube that can endure 900+ degree . Because i also need to do stress analysis of the inlet pipe of hot air , the allowable stress would be important to me . I hope somebody would help !

[T.S.MURALI]

You have considered worst condition of hot air/hot fluid.
Average/metal temp. should be less.
Material like SA213 T92 should be good.
Approximate stress required to cause rupture in 10000 hrs at 870 Deg C, for respective materials are:
HR120 alloy 40 MPA
Hastealloy x 27MPA
Alloy 600 16MPA
Typical SS310 12MPA