Square Tank Standard

[pstress]

I am preparing a data sheet and specification for square carbon steel tanks. Tanks are about 4000 gallons and are used on an oil rig. Does anyone know what an appropriate Standard would be? API 650 probably does not really apply since it is for cylindrical tanks.

 

[nickelkid]

ASME Section VIII Division I Mandatory Appendix 13 covers vessels of a noncircular crossection.

 

[pstress]

Thanks, good point. Perhaps I'll tell them to use ASME VIII, Div.1, App. 13 for the pressure design of the shell. Since ASME VIII doesnt cover alot of atmoshperic tank related design issues, perhaps I'll tell them to use API 650 as a guideline for welding, nozzle details, and QA/QC....what do you think?

 

[Bonswa]

Does it HAVE to be carbon steel?
What will be the service? Potable Water?

One of my customers has four square stainless steel storage tanks that we inspect using API-653 as the standard. Each of them is approximately 25'L x 20'W x 8'H. Each has a sloped flat bottom for draining. They are all atmospheric as they have open vents atop.

I pulled up the latest inspection report, where we also document the information on the nameplate; however there was no nameplate attached. I will try to contact that customer "out of curiousity" and see if the construction code is listed on the original construction drawings.

 

[nickelkid]

Combining standards can get messy, especially when QC gets involved. I would stick with ASME as the primary design and acceptance code; and supplement with API650 only in areas that ASME Section VIII Division I does not address.

 

[arto]

Blodgett's Design of Weldments & Design of Welded Structures have a nice analysis method for rectangular tanks

 

[pstress]

Good points.

Bonswa - would be interested if they designed and built it to a code.

 

[MJCronin]

A couple of points....

There is no "standard" devoted to rectangular cross section tanks. Any adaptaion or reading of API-650,620 or 653 for a rectangular cross section is well intentioned, wishful thinking.

Tank design particulars were discussed in this thread:

http://www.eng-tips.com/viewthread.cfm?qid=203490&page=9

Rectangular tanks are expensive on a $per gallon basis.

-MJC

 

[Bonswa]

I called, but no one answered. My contact works 4-10's, so he will not be in until Monday. I'll talk to him then and see if I can get some information. At LEAST, I should be able to get a manufacturer and go from there. I'll post when find out any information.

 

[unclesyd]

Here is a little information from UL 142 on rectangular storage tanks from the UL.

http://ulstandardsinfonet.ul.com/scopes/scopes.asp?fn=0142.html

http://ulstandardsinfonet.ul.com/tocs/tocs.asp?doc=s&fn=0142.toc

 

[Bonswa]

unclesyd is right...

The only reference to rectangular storage is UL-142. If you have access to IHS, pull up UL-142 (Steel Aboveground Tanks for Flammable and Combustible Liquids). There's a TON of great information in there about rules and guidelines for rectangular/square storage tanks.

The latest revision is December, 2007. That's the ONLY formal standard that I could find that covers it. I'm not sure what you're storing in this tank, but make sure the specific gravity doesn't exceed 1.0. Also, make sure that this tank will be stationary. UL-142 doesn't cover higher specific gravities than 1.0, and it also doesn't cover portable tanks. Section 1.3 in the scope sounds like it must be a shop built tank, tested before sent out. Also, the standard doesn't cover special considerations for natural disasters.

That's all I've got.

 

[vesselguy]

pstress,

I agree with arto's advice to use Blodgett's Design of Weldments & Design of Welded Structures. When I work in Minining side, I had done many designs of rectangular tanks using the method in this book. I also looked around and there is no standard or code for this sort of things. Alternatively, you can also refer to Roark and Young for the excellent formulas for rectangular plate solutions. For both methods you just have to define what is an acceptable plate deflection to you.

 

[Bonswa]

arto / vesselguy, I'm not familiar with Blodgett's Design of Weldments & Design of Welded Structures. What types of product service is this guide limited to? Surely, it can't be open-ended. The first thought that came to mind, when I read the question, was a structural code; however you're limited on product storage.

We STILL need to know what is going to be stored in this tank. Being offshore, I'm guessing it's either a potable water, cleaning solution, or fuel gas. I can't think of many other things that you would store in such a small tank, unless it's going to be used in the actual process of the platform; and the configuration of a circular tank will not work.

I have to disagree with you, when you say "there is no standard or code for this sort of things." The reason I'm going with UL-142 is because it IS an actual ANSI standard, and it covers flammable and combustible liquids.

Below is a copy of the Scope of UL-142:

1 Scope

1.1 These requirements cover steel primary, secondary and diked type atmospheric storage tanks
intended for noncorrosive, stable flammable and combustible liquids that have a specific gravity not
exceeding 1.0 in aboveground applications.

1.1.1 Each tank type may be fabricated in a combination of various shapes (cylindrical, rectangular or
obround) and orientations (horizontal, vertical) with or without multiple compartments, as covered in this
Standard.

1.2 These tanks are intended for installation and use in accordance with the Flammable and Combustible
Liquids Code, NFPA 30; the Standard for Installation of Oil-Burning Equipment, NFPA 31; the Motor Fuel
Dispensing Facilities and Repair Garages, NFPA 30A; the Standard for the Installation and Use of
Stationary Combustion Engines and Gas Turbines, NFPA 37; the Uniform Fire Code, NFPA 1; and the
International Fire Code published by the International Code Council.

1.3 The tanks covered by these requirements are fabricated, inspected and tested for leakage before
shipment from the factory as completely assembled vessels.

1.4 These requirements do not apply to tanks covered by the Specification for Field-Welded Tanks for
Storage of Production Liquids, API 12D; and the Specification for Shop-Welded Tanks for Storage of
Production Liquids, API 12F.

1.5 Deleted

1.6 These requirements do not cover special evaluations for resistance to hurricanes, tornadoes,
earthquakes, floods, or other natural disasters; or resistance to vehicle impact.

1.7 These requirements do not cover portable tanks intended for transporting flammable or combustible
liquids (such as shipping containers), or mobile use applications (such as mounted on a trailer). These
types of products are covered by separate UN, DOT, or equipment product standards.

 

[vesselguy]

Bonswa,
You have good points, however let's not over analysis this kind of tank. I'm not knocking the UL standard that you posted here. I too have written engineering notes to go with my RFQ package for these tanks that specified similar requirements, and in fact more, that's list in this simple UL spec. What's stated here is basic good engineering practice that any good engineer would have already specified in his package.

It is my fault that I missed the orignial poster's point that he is only asking for a standard and not design method. You are right.

 

[pstress]

The tank contains drilling fluids and client wants it square. I think I will go with UL-142. I dont have a copy but I will track it down.

Great answers, everyone. Thanks.

 

[arto]

Blodgett's books are the best $15 you'll ever spend!!!

https://ssl.lincolnelectric.com/foundation/store.asp?PID=16&cat=8