Analysis of straight flange on pressure vessel head 2

[UMR]

Is there a published ASME "opinion" that the straight flange of a pressure vessel head does not have to be designed as a shell element? APV software does not include the straight flange in the head analysis but Compress appears to do so.

 

[brandonb73]

UG-32(l) requires the skirt thickness to the be same as for a seamless shell of the same ID.

 

[UMR]

Thanks Brandon. That is technically what I am looking for. An associate engineer thinks ASME has provided an opinion beyond the code that says the shell analysis of the straight flange isn't necessary but I've not been able to locate such a statement.

 

[brandonb73]

That being said, I ran a design scenario through APV for a seamless shell (85% eff.) and a head with 100% eff. in order to make the min req. thickness of the head less than the shell. It did not give me an error.

 

[vesselfab]

I think that is says the required thickness of a seamless shell under same conditions.

 

[UMR]

Good point Brandon. The difference in E values probably offsets most of the time. I appreciate your help.

 

[CodeRef]

I highly doubt that the ASME would have the opinion that the straight flange of a pressure vessel head does not have to be designed as a shell element.

After all, it is a shell element up to the tangent line where the shell becomes a head. Thus the reason for the 3:1 tapered transition per UW-13.1 as well as provisions in UG-32(l) only when the formed head is thicker than the shell, concave to pressure and intended for butt welded attachment

Parsed from UG-32(l)..........All formed heads concave to pressure and intended for butt welded attachment need not have an integral skirt when the thickness of the head is equal to or less than the thickness of the shell......


FAQ731-376

 

[UMR]

Thank you for your post. I agree with you completely and that is why I brought it to this forum of experienced designers. Your support and advice will allow me to change a design practice that has been out of bounds for some time now. Best regards.