Dear all,

In design calculation report of a pressure vessel with skirt support I could find that the allowable compressive stress values for empty and corroded condition varies...
How its related to the weight....
Can anyone please help me?

Hello Abijith

It is probably related to whether the corrosion is deducted in one case and not in the other case. Perhaps you could send me your model?

The above doubt is clarified, but I wish to have another one regarding the calculation of skirt support itself, where the use of allowable compressive stress whlie calculating the required thickness values in both sides....

It is understood that the allowable compressive stress values are taken according to the unit stress that is calulated per unit length. Then resultant is checked weather the stress is compressive in nature or tensile ...
This method provides the nature of the stress, after that re calculate the stress values in both sides with the given values ...

Can anyone tell me the reason y the unit stress value determine the sign or nature of the resultant stress....
Y it is not same for actual stress values....

Hello Abijith

In the case of ASME Section VIII, Division 1 vessels, the maximum allowable tensile and compressive stress is stated in paragraph UG-23. Unit stresses are not mentioned. In the case of occasional loads, a factor of 1.2 can be applied thus increasing the allowable stresses. Wind and seismic load are classified as occasional loads. Division 1 considers principle stresses, and Division 2 consider stress intensities.

In the case of skirts with access openings, the method outlined in the European EN 13445 code is used. There, the allowable stresses are different.