Standards for leg-supported vertical atmospheric conical bottom tanks

[andrew_]

Hello,
I posted this in "Codes and standards general discussion", but then discovered there is a full section on storage tanks... So I will post it here!

I've been through may posts on this forum and am still struggling with a particular topic.
I am looking for the relevant design standards for leg-supported vertical atmospheric conical bottom tanks.
These tanks are to contain media such as water, mineral oil, caustic etc.

As far as I understand (please correct me if I am mistaken)
1) there are standards for pressurised vessels (ASME VIII, PED 2014/68/EU, EN 13445, AD2000)
2) there are standards for flat bottom atmospheric tanks only (API 620, BS EN 14015:2004)
3) there are standards for flat bottom atmospheric tanks with no restrictions for "non flat bottom" (API 650, BS EN 1993-4-1 and 2)

Is one of these actually applicable here?
Would it be "best practice" to design to pressurised vessel standards but with atmospheric design pressure?
I ask because I have seen many tanks as I described according to ASME VIII-1.

Same question for the same type of tank with -0.5 to +0.5 barg design pressure. Would that have to follow the standard for pressurised vessels?

Same question for the same type of tank with a design for full vacuum. Would that have to follow the standard for pressurised vessels?

 

[HTURKAK]

DEAR Andrew_ (Mechanical),The same thread was in 'Codes and standards general discussion FORUM'.
I copied pasted my comment to share the knowledge...

HTURKAK (Structural)17 Apr 20 08:39
Dear Andrew_ (Mechanical),

Your quote 'As far as I understand (please correct me if I am mistaken)'

1) there are standards for pressurised vessels (ASME VIII, PED 2014/68/EU, EN 13445, AD2000) .OK. TRUE ..
2) there are standards for flat bottom atmospheric tanks only (API 620, BS EN 14015:2004)..NO!..API 620 FOR LOW PRESSURE STORAGE TANKS!!!
3) there are standards for flat bottom atmospheric tanks with no restrictions for "non flat bottom" (API 650, BS EN 1993-4-1 and 2). TRUE BUT ENTIRE BOTTOM IS UNIFORMLY SUPPORTED, AND THE SLOPE FOR DRAW OFF TO CENTRAL PIT,ESSENTIALLY FLAT BOTTOM.

Your quote 'Is one of these actually applicable here?' NO!!!
Your approach should be HYBRID.. Regarding Liquid-Filled Elevated Tanks , for dimensions ,piping etc pls look AWWA, For the design of shell =You may look AWWA D100 + API 650, For the design of conical bottom and roof = pls look any handbook for design of shell and plate structures applicable formulas WOZNIAK (E.g)

You may look also=Eurocode 3 — Design of steel structures —Part 4-1: Silos

In case of -0.5 to +0.5 barg design pressure or full vacuum , pls look ASME codes.

 

[JStephen]

ASME allows leg-supported tanks and vessels, but doesn't give much guidance in design, either. The various vessel handbooks include limited information on the topic. If your tank/vessel is exactly like what they address, it can be helpful.
I believe API-620 allows the construction of leg-supported tanks, but doesn't address the design of the legs. It is mainly intended for vessels supported uniformly, as on flat ground or on a skirt. It is useful in that it specifically addresses design of suspended cone bottoms and of compression rings for suspended cone bottoms.
AWWA D100 addresses design of leg-supported tanks in the form of water towers, but doesn't have give much help for design. Those who use it for these tanks are normally building very similar tanks over and over.
Normally, tanks and silos that are leg-supported with cone bottoms will be built as non-code vessels, built per a particular standard "to the extent applicable".
For pressures in the ASME range (over 15 psig), they would be built as code vessels.
For 0-15 psig, they might or might not be built per API-620.

 

[andrew_]

Thank you for your answers.