I have a case where in the analysis is too conservative if we consider the design temperature furnished by the process department. I am putting forth a simplified version for the discussion forum.The line is an header with two tappings .Both the lines are separated by a distance of 50 mts .The upstream line design temp is 330 deg C and the down stream one is 50 deg C . So naturally the header design temperature is taken as 330 deg C by the process department. Now our company standard says analysis of the line is to be done using the design temperature as given in the line list . In this case I would like to contest the temperature to be used for analysis between the two tappings since there will be a temperature gradient .Please note the main header is exposed to ambient conditions and is non insulated.

My queries are as follows
1)Is it ok taking the average temperature for the line between the tappings.
2)Are there any temperature gradient values for stainless steel / carbon steel exposed to ambient temperature , surely I can imagine the college day empirical formulas with thermal conductivity and heat transfer coefficients thrown in as complications. Any easy to use data or thumb rules available ???. :rolleyes:
3)What do my other friends in the discussion forum do when they are faced with such problems.

Please note in my case I could avoid giving unnecessary flexibility to the expensive alloy steel line tapped upstream.Also if someone comes out with a very sound technical explanation I can analyze the system more near to actual conditions and defend myself.

S.C.RAO

TESSAG EDELEANU ASIA PTE
http://www.edeleanu.com.sg/

[ September 06, 2001: Message edited by: Shivaprakash C Rao ]

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