AS 1940 Crest Locus tank/bund interpretation

[AUFC204]

Hello all,

I am interested to know how any of you may have interpreted and applied Clause 5.8.3(h) of Australian Standard AS 1940 The storage and handling of flammable and combustible liquids.

The clause reads as follows:

"The location of a bund relative to the closest tank shall be such that the top inside perimeter of the bund is not inside the crest locus limit specified in Figure 5.2, except where it can be demonstrated that a reduced distance would be appropriate due to viscosity or other considerations." I have attached Figure 5.2 from the standard.

So if you look at the figure, it seems pretty straight forward that 1 metre minimum horizontal separation between the tank and its bund wall is required for bulk storages of flammable and combustible liquids - and potentially greater separation is required if the crest locus calculation shows this. Straight forward that is until you find that many *apparently* AS 1940 compliant tank/bund packages on the market have less than 1m horizontal separation between the storage tank and its bund wall.

This is just a sanity check that I am interpreting these requirements properly. Is there another way to interpret the clause - for example, that the crest locus is the hypotenuse of the triangle and not the base...

Anyways, sorry for the boring technicalities above and hope there is someone who can help.

Thanks,
Paul

 

[JStephen]

Could it be the "or other considerations" kicking in? Perhaps people were able to show that if their tank configuration failed, a lesser distance was okay?