Temperature load
Temperature load
(OP)
Hello!
I have some questions about temperature in pressure vessel.
Suppose that I have pressure vessel which operation (or design - it doesn`t matter) loads only P, Ps, D and T.
to evaluate the vessel I use elastic-plastic analysys acc. ASME VIII div.2 part 5.
So I should use load combinations from table 5.5. They are:
1)2.4*(P+Ps+D)
2)2.1*(P+Ps+D+T)
3)2.1*(P+Ps+D)
*cases with P=0 we will not consider for simplification
Questions:
a) Can I don`t consider the third combination because 2.1<2.4 ?
b) Should I use material properties according temperature = T even there is no T in load case?
c) Why is T in only one load case although P can`t exist without T as a rule.
Thanks!
I have some questions about temperature in pressure vessel.
Suppose that I have pressure vessel which operation (or design - it doesn`t matter) loads only P, Ps, D and T.
to evaluate the vessel I use elastic-plastic analysys acc. ASME VIII div.2 part 5.
So I should use load combinations from table 5.5. They are:
1)2.4*(P+Ps+D)
2)2.1*(P+Ps+D+T)
3)2.1*(P+Ps+D)
*cases with P=0 we will not consider for simplification
Questions:
a) Can I don`t consider the third combination because 2.1<2.4 ?
b) Should I use material properties according temperature = T even there is no T in load case?
c) Why is T in only one load case although P can`t exist without T as a rule.
Thanks!





RE: Temperature load
b) it would be best for you too better understand the relationship between temperature and thermal loads. All design conditions must be evaluated at the Design temperature, including material properties, such as Young's Modulus.
c) T is not temperature. See Table 5.2.
Just to confirm, you are also satisfying ALL of the other failure modes? Thermal loads typically become important for fatigue and ratcheting.
RE: Temperature load
Thus, in cases where the load T is not involved, I still use temperature to find the temperature distribution to automatically take into account the desired properties of the material, and assign alpha=0 (linear expansion coefficient) to remove the load from the non-free fixing.
Is it right? Or could I overlook something?
And of course other failures are satisfying.
Thank you!
RE: Temperature load
RE: Temperature load
c) T is not temperature. See Table 5.2."
Koefficients with loads only show us whether this load dominate in this case or not (or this load absent in this case at all) and probability its appearance.
So...let we have a pressure vessel with not free fixing. Then I will have thermal loads anyway. Probability= 100%. So I think we should consider load T in all cases (koeff I think should be the same as P and D have in appropriate cases).
For example, why in case (4), when W is considerable, thermal loads from not-free fixing don`t act?
I`m looking forward the answer.
RE: Temperature load
The easiest explanation that I can provide (and it is worth exactly what you paid for it) is that it is rare that thermal loads cause plastic collapse.