Which Code Applies for Small Full Vacuum Tanks? 1

[redsouther]

I have been asked to design a small tank (31" dia x 144" tall) to be used as a water/air separator. The tank is to be designed for full vacuum and atmospheric positive pressure, and is to be shop tested to 1.5 times working pressure.

I know that the pressure vessel code covers tanks above 15psig, and that API 620 covers positive pressures up to 15psi, but I am not sure how to classify this particular tank.

I have a good bit of experience designing liquid and bulk solids storage tanks, but am not as familiar with pressure vessels. Any advice would be appreciated.

 

[JohnBreen]

Hi redsouther

You design it to the ASME B&PV Code, section VIII, Div. 1 and pay attention to UG-28 et al.

Regards, John.

 

[redsouther]

Thanks for the help.

 

[weeeds]

See U-1(c)(2)(h) for an exemption that seems to apply to you

 

[SnTMan]

redsouther, Ther are kind of two issues here.

1) You may design to Sec VIII, Div 1, or another code of your choice, if all you need are design rules and practices.

2) You may or may not be able to exempt from inspecton, stamping, and so forth, depending on your jurisdiction and choice of code. What does your locality require, if anything?

You may want to spend a little time looking into that side of things, it could help firm up what you need to do.

Regards,

Mike

 

[MJCronin]

red..

IMHO, you should specify a design pressure (MAWP) of 15 psig and FV, pay the extra 5% for the records and classify the component as a pressure vessel.

This way, you get a full set of calculations, a code stamp and the assurance that the design is correct and the materials are of quality.

The pressure that you actually operate the vessel at is your business.

-MJC

 

[arto]

Watch out for forces & moments from nozzles, etc.
There was a good old article on the subject by N.Gilbert & J.R.Polani, "Stability Design Criteria for Vessels Subjected to Concurrent External Pressure & Longitudinal Pressure Loads," Trans. ASME Jnl P.V. Tech. Vol. 101 May1979, pp178-81