Custom Flange thickness for atm tank 1

[mikey21]

Hello.

I have problem with my design calculation for atmospheric tank. I cannot find the right thickness to use for the top cover flange.

Let me give some details:
Material shell= SS304L
Tank Outside diameter= 700mm
Tank shell length = 1300mm
Design pressure: Atm
Design temperature: 50 deg celcius

The tank is designed to have top cover so we plan to use customized OD800 X ID700 bolted flange and OD800 blind flange as top cover.
My colleague, from his previous company, used 10mm thick for the bolted flange but now we have to do some calculation to show that the thickness is enough
to hold 1 manhole on top of the cover.

Manhole dimension:
OD: 400mm
Length: 100mm
Material: SS304L

Will appreciate anybody's help. Thank you very much in advance!

 

[fegenbush]

I would treat this design as a annular plate with an inner diameter equal to the small manway (400 mm) and width equal to the largest gap between the diameters (250 mm). The outer diameter would then be 900 mm. Then use Table 11.2 Case 1a of Roark's Formulas for Stress and Strain (7th edition) to calculate the minimum thickness. Regardless of the calculated thickness, I would not use a thickness less than that shown in Figure 5.16 of API 650 (12th Edition, 1st Addendum). You may require a thicker plate if the gasket surface is to be machined.

 

[mikey21]

Thank you fegenbush! Totally helped!