Double Walled API650 Tank

[crossbow]

I have been asked by my client to change our design for a 110m3 API650 (shop erected) heavy fuel oil tank from a single wall to a doubled walled construction due to a space restriction on site. My experience is with single wall tanks, could someone please advise where I may find the design requirements and therefore details for the cavity spacing, hold down bolt methods and kerb angle connection etc for a double wall tank.

 

[JStephen]

UL-142 includes double-wall tanks, but doesn't really give many specifics on how things are to be done.

 

[crossbow]

Thank you for the advise I have sourced a copy of UL-142 but as you noted it does not show specific details. I will need to keep searching as we have a high seismic requirement and I need assistance with the chair details to connect the two shells in some way.

 

[MJCronin]

These people have done many double walled tanks:

http://www.recoconstructors.com/

 

[gr2vessels]

First I suggest to google 'self bunded fuel storage tanks'. You'll be busy for a while...
Secondly, the Australian standards could be your answer;- AS 1940 and AS 1692. Thousands of self bunded fuel storage tanks are used in Down Under, including other flammable liquids like methanol/ethanol, etc. Industrial, tank farms, small and large storage facilities.
The gap between shells is minimal, down to fabrication tolerances required to slide the inner strakes inside the external shell. Use some welded 'sliding strips' (3mm thick strips) in the lower half of external shell to support the inner shell and allow 'volume' for the fluid (fuel) to flood the interstitial space in case of containment loss of inner shell. This space will enable detection of liquid between the shells with a dip stick smeared in the end with water detection paste, diesel detection grease or alcohol detection paste. You will have to use the venting and overpressure regulations strictly, because that's the main protection for these tanks.
Cheers,
gr2vessels

 

[crossbow]

Thank you for help with this post.