5 replies to this topic

[Ibnu84]

Hello All,

What is the design pressure of atmospheric tank. Does it include static head?

I have an open drain tank with a vent routed to atmosphere 3 m above the tank. Unfortunately it does not have overflow line. Thus the tank is designed full of water up to the top of vent line.The tank height is 3 m, so that pressure at tank bottom equals to 0.6 barg. Does it mean the tank design pressure is 0.6

PED will be applicable for tank with PS (design pressure) more than 0.5 barg. In my case, is PED applicable?

Thanks

Edited by Ibnu84, 18 June 2015 - 11:16 AM.

[fallah]

Ibnu84,

 

The atmospheric tanks aren't designed to be full of water up to the top of vent line at all. Then mentioned tank can be full of water only up to 3 m height; but nonetheless the tank's design pressure depending on the roof weight is a few mbarg...

[shan]

API 650.  3.1.2 design pressure: The maximum positive gauge pressure permissible at the top of a tank when the tank is in operation.

It does nothing with the level of tank liquid.

[latexman]

Just do NOT specify the design pressure as "atmospheric pressure"!  Even with an open vent there will be backpressure during credible scenario flows.  Be conservative.  Give some cushion (safety factor).

 

Old tanks that were specified as "atmospheric pressure" have caused me all sorts of issues in todays world of API driven relief sizing!  Don't do this to those that follow us!

[Ibnu84]

As per norsok P-001, where no overflow line the tank need to be design full of liquid upto the vent line.

Well, should i say that the tank design pressure is 0.07 barg with a note saying that for thickness calculation a static head of 6 m shall be considered.

Any body knows whether PED apply to this tank?

[shan]

You are confused tank design pressure with tank shell stress.