Thermal Cycling
Thermal Cycling
(OP)
Hello,
I have a vessel (drier) designed to ASME VIII Div 1 that is undergoing daily temperature swings from 100F (38'C) to 380F (193'C) within half an hour. The design conditions are 260 PSIG @ 500F.
Is there any guidance on allowable temperature swings before you need to assess for thermal fatigue?
I have a vessel (drier) designed to ASME VIII Div 1 that is undergoing daily temperature swings from 100F (38'C) to 380F (193'C) within half an hour. The design conditions are 260 PSIG @ 500F.
Is there any guidance on allowable temperature swings before you need to assess for thermal fatigue?





RE: Thermal Cycling
"...when logic, and proportion, have fallen, sloppy dead..." Grace Slick
RE: Thermal Cycling
In VIII-2 there is fatigue screening Method B available. Try that to see if you pass. What matters is the temperature gradients - if the temperature rise and fall are gradual, you may not have any issues.
Still, a thermal fatigue analysis is not particularly expensive...
RE: Thermal Cycling
I took a look at the screening method B (5.5.2.4) and it looks as though I am interested in Steps 5 - 8. correct?
In steps 5 - 7 it asks for a maximum temperature difference between to adjacent points, with the adjacent points calculated using L=2.5SQRT(Rt).
Would this not assume I have a circumferential mal-distribution between two locations on the drum? I am trying to assess the drum heating and cooling equally over the entire drum. Am I missing something here?
RE: Thermal Cycling
I took a look at the screening method B (5.5.2.4) and it looks as though I am interested in Steps 5 - 8. correct?
In steps 5 - 7 it asks for a maximum temperature difference between to adjacent points, with the adjacent points calculated using L=2.5SQRT(Rt).
Would this not assume I have a circumferential mal-distribution between two locations on the drum? I am trying to assess the drum heating and cooling equally over the entire drum. Am I missing something here?
RE: Thermal Cycling
RE: Thermal Cycling
Appreciate the help by the way.
RE: Thermal Cycling
RE: Thermal Cycling
Does the whole vessel cool down to the 39 degrees, or does most stay hot when the vessel is opened and refilled? Is the interior rapidly chilled when it is refilled with cold ? product, or does the inside wall slowly cool?
RE: Thermal Cycling
Thickness of the drum is 32mm with a total height between Tan's of 6100mm. ID is 1675mm. Heads are 2:1 Semi 33mm thick.
RE: Thermal Cycling