Studding Outlet - Max Bore

[BagassePileOfStuff]

Hello, I am designing a conical shell that will have four 300# 1" studding outlets spaced around it at the same elevation. Due to process/wear (we use an insert to protect the SO and shell from wear otherwise we'd need to repair too often) requirements, the process engineers have asked me about opening the bore on the studding outlets up to 35+mm. I'm relatively new to vessel design so I sat down and took a stab at the calculations from UG-36 through UG-42. If I did it right then 35 is no problem, however, I do not think I did this correctly because not only is 35 not a problem but it seems like I can make the studding outlet ID whatever I want.

Am I using the correct section of the code and is it possible I'm using it incorrectly? The housing has an ID of 300 mm so it isn't very big, design conditions are 18 bar and 210 Celsius. Both the studding outlet and the shell are 2205. I calculated an area required (A) of just 87.5 mm^2. I also got A1=262.5 mm^2 and A2=659.06 mm^2. I stopped here and rechecked everything I did and ended up not bothering to calculate A3 or either A4. If I am incorrect I'm guessing I found incorrect values for tr, tn and/or trn.

The closest sketch in UG-40 to the configuration is a-1 though the opening in the shell matches the bore of the SO and there is a v-butt weld between the two.

Thank You,
Tom

 

[racookpe1978]

Provide a scale sketch or dwg view (elevation view most likely best) of the proposed head and nozzle positions. Unfortunately, your configuration is not clear from your description above.

 

[BagassePileOfStuff]

Here is a view of the studding outlet as it will need to be. There will also be a capture of the way my drawing currently shows the housing to follow.

 

[BagassePileOfStuff]

Here is the housing. I miswrote yesterday when mentioning the ID. The housing has a liner with an ID of 300, the actual calculations should be performed as if the ID is 306.35 mm.