THERMAL RATCHETING 1

[MILSPEC4]

Gentlemen;

My question deals with the treatment of the both a shell and a tube which are subjected to relatively high heat flux from the gas side to the water side. (say 1+/- Btu/sqin sec)

When does the combination of heat flux and metal temperature enter the realm of thermal ratcheting and how this is dealt with under division 1 or division 2 in ASME section VIII?

Is there any guideline in terms of flux or temperature and what section of code addresses this type of problem (as opposed to the more normal use of allowable metal temperatures and the allowable stress therefore)?

(This application does not envision that the metal temperatures will exceed those which are allowable for the appropriate material in the code stress tables.)

Any thoughts which you might have on the subject would be greatly appreciated

 

[doct9960]

MILSPEC4,

There are thermal stress ratchet rules in ASME Section VIII, Div. 2, Appendix 5, 5-130. The rules are only for radial temperature gradients.

 

[MILSPEC4]

doct9960

Thanks for the lead. I will followup ASAP.

MILSPEC4