Storage Tanks MAWP/V Calcs 1

[kevllt]

Hi fellow Mechanical Engineers,

I have some difficulty in calculating the MAWP & MAWV of low pressure Storage Tanks. I had spent long hours on the Pressure Vessel Handbook and I'm still not sure about the relevance of my calculations. I have almost a hundred tanks to determine the MAWP/V, some conical and dome type roofs, for one of our major clients before sizing pressure relief devices for those tanks. Please advise.

Frustrated engineer,
Kevin

 

[LSThill]

Need more information

API or ASME TANK?

 

[JStephen]

It sounds like these are maybe flat-bottom API type tanks? If so, pressure vessel info won't do you much good. You need API-650, Appendix F, and API-620. Recommended venting capacities are covered in API-2000.

The calculations can be set up in a spreadsheet form IF you have the information to go into it. If you don't have decent drawings of the tanks, it could turn into a chore.

The allowable pressure of a flatbottom tank is dependent upon, among other things, the wind overturning forces, so you get to figure that as well.

 

[carthago]

Well if you talk about API 650 and/or 620 .
API 579 Give somme guidances.
One should know:

* the actual thicknesses as measured.
* The reamaining life ( translated into a sort of reserve thickness or future corrosion allowance)= FCA.
* the specific gravity ( worst case)

Materials should be correctly identified..

Tank general drawings, details, materials and their certificates, should be all available before hand

And calculate
Hmax = function( D,Thickness, Specific Gracity)

 

[codeeng]

The 3 most import areas are the roof, the roof to shell joint and the uplift due to wind plus pressure. All this is covered in the API standards. Like JStephen says you won't find this in the PV Handbook.

 

[JoeTank]

Internal pressure will be limited by one of these...
Roof plate tension.
Compressive strength of shell-to-roof details.
Shell plate tension, but not likely.
Uplift at base of shell.
Anchorage, if any.
Whether it is to be applied in combo with wind loads.

External pressure will be limited by one of these...
Roof plate strength.
Roof structural strength.
Tensile strength of roof-to-shell details.
Collapse of shell.
Longitudinal compression in shell.

Hope this helps

Steve Braune
Tank Industry Consultants

http://www.tankindustry.com

 

[kevllt]

Thanks everyone for all your precious inputs. Thanks for guiding me into the right track, cause I would have based my calculations on the PV Handbook, if it wasn't for y'all's precious comments. Will any of you care to review my spreadsheet once I'm done? Thanks.

kevllt

 

[carthago]

Gentlemen, you are right
----------------------
Can add the valve capacity.

----------------------

Please allow me to correct my answer above.

Regarding API 579

Hmax = function( D,Thickness, Specific Gracity)
Depending on type of damage.

Hmax is what actually what is known as MFH , or maximum Fill hight of the tank.

This is not the the MWAP

 

[kevllt]

Mr Carthago,
Thanks for your further explanation. I was almost confused the use of API 579. I really appreciate all your effort though.

To All,
I do realize that there are many engineers out there who has already developed a spreadsheet to calculate MAWP/ MAWV for API 650 Low Pressure Tanks. I am going to try to make one of my own too, and I would really appreciate any inputs whatsoever dring this process. Thanks all...

Mechanical Engineer,
Kevin

 

[LSThill]

RE: Do you want in english or Span.

Please do a detail advance search "API 650 TANK PROGRAM" was posted in 2002

 

[JStephen]

If the 100 tanks were all identical construction, the spreadsheet isn't too complicated. That's probably not the case, though. You will quite likely spend more time trying to figure out the exact details of construction for each tank than you will doing analysis.

There are some tank programs out there, but they aren't necessarily geared towards this application, and may or may not be convenient to use for it. In any case, in using the programs, you need to understand what the program is doing and how and why in order to use it effectively.

 

[vasilij]

I think that better solution refer to good software, for example, Compress, Codeware

Yuri

 

[carthago]

But software such Codeware and Cmpress do not cover storage tanks!!

Even a software like Tank ( for API 650 / 653) does not deal in an extensive way with roofs.

I think one has to come back to the basics : Code, good judgment and common sense..

 

[kevllt]

Hey fellow ME's,

I am finally done with my spreadsheet for the API 650 Low Pressure Tanks MAWP/V calculations. Thanks.

Kevin

 

[djack77494]

Kevin,
I'd suggest that you post your spreadsheet if it's possible to do that. I would be happy to take a look at it, and I'm sure you'd get many other lookers.
Regards,
Doug

 

[kevllt]

To: Doug & All the Experienced Engineers out there,

I really appreciate your offer to help me review my MAWP/V Calcs spreadsheet. I've posted the spreadsheet on my public URL at

http://www.geocities.com/kevllt/LPTank/MAWP_V.htm

All comments and suggestions are very much appreciated.

 

[vesselguy]

kevllt,

I am too late to give you something that would help you. But, I had done API tank vacuum rating many moons ago when I worked at Fluor. I followed a document in the DuPont Standard to do this work. The DuPont standard is the only document I know that gives the vacuum calculation proceedure in detail. I heard that API-650, in their next update, will incorporate the DuPont Stardard's method. Now, I don't have the standard anymore, because I signed an agreement with them to not make copies. Yes, ETHICS!

So, if you can find someone who's can give you a copy of the DuPont Standard for API tank vacuum cal then you're in.

To some others, you can't apply pressure vessel programs for everything. Come on..