Installing a Mixer on a Tank Manway

[collism]

I am looking at installing a mixer on a standard tank manway opening. We have several mixers in service currently, but they are all on tank nozzles. I can't find any guidance from API 650 or 653.

The mixer vendor has calculations, but they only take into account the stress at the weld joining the reinforcement pad to the shell. I can't see why the stresses at the welds from the flange to the nozzle, or nozzle to shell can be disregarded.

Any ideas? Any calculations that you know of to check this?

 

[arto]

try Walther J. Stikvoort's article:
"Proper Interface Design for Pressure Vessels" in Chemical Engineering June '94 p133-4.

 

[johnnymist2003]

Hi,

You need to get the loads induced by the agitator from the supplier. You'll need axial, bending moments, torques. They may also be able to give you any shear loads generated.

I'd check the stresses in the flange (using equivalent pressure method), maybe use ASME VIII, Div.1, Appendix 2, or some scuh pressure vessel code. You could check the stresses in the nozzle neck using PD 5500, Annex B. You could also check the stresses in the shell using API 650, Appendix P. Remember, the nozzle does not know that it is a process nozzle or a manway, the loads will still act in the same way for both.

Hope this helps
John