12'-0" diameter 400 BBL Storage Tank set @ 5psi working pressure 3

[merton]

I received a request for a 400 barrel storage tank set at a 5 psi pressure rating. The original design code specified API 12D. I explained that his code does not cover a 400 BBL tank and definitely not a tank with a 5 psi working pressure. I suggested that this piece of equipment be treated as a pressure vessel and be constructed to the set of codes governing this design.

I inquired if anyone had submitted a tank designed to 5 psi and there was one. The design code was a API 12F/650/620. I don't believe you can mix and match these codes to suit a specific project.

I realize that 12F and 650 cannot be used to design a tank to 5 psi pressure. And as I interpret API 620, it is for large storage tank with low internal pressures, so a small tank such as this would not meet the requirements as laid out in the specification.

Sorry, to ramble on. I am just wondering if my interpretation of these codes is correct and to confirm if I led this gentleman in the right direction. Any addition suggestions or interpretations would certainly be appreciated.

Thank you.

 

[butelja]

I would lean towards either API 620 or ASME Sec. VIII, Div. 1. As I read the scope of API 620, it says it is for &quot;large&quot; tanks, but I don't see any definition of large. So long as you are < 15 PSIG and < 250 °F, I don't think this tank is precluded from API 620.

Then again, I'm married to an attorney, so maybe I'm just hung up on looking for loopholes.

 

[MJCronin]

merton,

400 barrels eh ?.... Hmmmmmm thats about 17,000 gallons which would fit (about) in a horizontal tank 12' diameter and about 20 feet long......a shop built tank

You could get such a tank designed, tested and certified in accordance with API 620 OR designed, fabricated and tested to ASME VIII (without the ASME code stamp)

The price, either way would be about the same....

Talk with the people at Modern Welding in Newark, Ohio (

http://www.modweldco.com)

and they will help you out. A nice guy by the name of Tom Griggs has been very helpful to me...

Good luck

MJC

 

[twjag]

API 620 is applicable to your tank. The term &quot;large tanks&quot; is somewhat irrelevant. API 620 is a design by analysis Code, as opposed to API 650, which is a design by formula Code. API 620 does not provide rules for external pressure. If you have external pressure, use the rules from ASME Section VIII, Div 1. For external loads (vacuum or live load) on conical roofs, use ASME for apex angles covered, or API 650 for flatter slopes.

 

[JOHNPIA2]

I took a quick look ar all API standards mentioned above. I do not see how these can be used to design horizontal tanks. They all specify they apply to VERTICAL tanks (see scope section); API 620 applies to tanks havind a single VERTICAL axis of revolution. Am I missing something?
Would a 12ft dia. x 24ft long, full of water, atmospheric, saddle supported, be made of .140in thick stainless 304 typical plate? For heads, conical, 75 deg. half-apex angle, and full rings are used over and between the saddles, to avoid ovalling.

 

[jay165]

merton:

In my experience, a tank your size made from CS is slightly cheaper if it is built to ASME Section VII rather than API 620, even if it is code stamped. Also, I found that if you use 3/8" plate and get the design pressure high enough, your relief valve is much smaller and you can use an existing LP header for a fire size case rather than a huge discharge line and atmospheric vent pole.

 

[JoeTank]

JOHNPIA2,
Buried somewhere in API-620 is a statement that it may also be used for horizontal tanks. It's hard to find, but it's there.

Steve Braune
Tank Industry Consultants

http://www.tankindustry.com

 

[PAN]

I'm not sure about API Standard for horizontal tank. However, I think the inforamtion below (Table 1) may be useful.

http://www.mass.gov/dfs/osfm/fireprevention/cmr/527009.pdf

 

[CHD01]

My experience is that the break point for API versus ASME design is approximately 20 ft diameter by 20 foot tangent to tangent. Less than 20ft diameter and the advantage is ASME.

The more you learn, the less you are certain of.