API 650 & Tank Software 2

[rotaryguy]

Hi guys,

i may be nutts but need help. i am using TANK software for Shell plate thickness calculations. problem is that i have to Design atmospheric tank as per 650. I require input design pressure on top (PSI). it is atmospheric pressure it should be 14.7 psi. but API 650 limits maximum design pressure to 2.5 PSI.

need pressure value?

 

[TankDude]

API 650 and the applicable design software view atmospheric pressure as 0 psig. So just input 0 and it should run the design.

 

[JStephen]

Yes, pressure there is "gauge pressure", not absolute pressure.

 

[panduru]

On a slightly different note, though:

In case of ASME Sec. VIII Div. 1 BPV Code, the design is intended for internal pressures above 15 psi (g, I believe). If the int. pr. is "atmospheric," the vessel can still be desiged as per code, I am told.

The formulas result in such small values of thickness that in most cases, the commonly used minimum plate thickness of 5 mm, turns out to be adequate for nearly every vessel of reasonable diameter. (Remembering that as opposed to storage tanks, reaction vessels are generally not so huge in size).

Am I missing anything here? I strongly suspect so.

If anyone would to discuss this on a separate thread of its own, I will start it.

Tx in adv.

 

[dig1]

Panduru,

A vessel with no gauge pressure (0 psig MAWP at top)can be designed per Div.1.

One thing that you did not mention is the difference in allowable stress between Div. 1 & API 650. There are also different treatments for nozzles between the two codes.

So using ASME software, such as PVElite, Compress, APV, and similar software to design an API storage tank is not technically correct because it does not comply with all the requirements of the API code. I've been thru this on the review end and it is a hassle to go back and forth several times.

I hope I intrepreted your comment correctly.

TANK is an API 650 software so the above discussion isn't applicable but I've seen what I mentioned done several times.

 

[rotaryguy]

yep i have been told i can designed storage tank using 0.0 psi as Tank software limits upto 2.5 psi as per API 650. thanks guys for your info it really help a lot for newbee like me.

 

[panduru]

Thank you, rotaryguy.