NFPA 22: Aluminum Rood Geodesic Dome Roof

[oddmanout]

Hello:

There is an ongoing debate in our office re: whether NFPA 22: Standard for Water Tanks for Private Fire Protection (2013) allows for the roof of a private firewater/service water storage tank roof to be a geodesic dome style cover constructed out of aluminum. I am being told that, per Section 6.2.1., it does not However, as I read the standard, I see nothing that prohibits it other than the statement in Paragraph 6.2.3.2. which implies that aluminum cannot be used where it will come in contact with the water.

Can someone please enlighten us on this issue?

Thanks

 

[stookeyfpe]

No. Section 4.4.1 is clear that the materials of construction are limited to steel, wood, concrete, coated fabric or FRP. Annex A does not offer any guidance on why Al is not permitted. It is most likely because Al has a lower melting point thatn carbon steel or wood. Note that coated fabric tanks are only allowed when partially or completely earth covered and FRP tanks are only permitted for underground installations.

 

[DavidCR]

I see that NFPA22 is clear that all tanks must have roofs and that Al is not included as material (reading my 2003 edition).

I wonder if this point has been ever considered by the NFPA22 committee. I see it an extrange case since the high cost of an Al cover may be not economically feasible, and maybe no one has ever had the need to use one for a water tank, since other options that are in the code are cheaper and OK.

Aluminum covers are considered good for oil tanks. I see no problem using them with a fire water tank.
In petrol industry you use Al covers for several reasons (complement for floating roof, solution for rain problems on foating roofs, no need for central column to support the steel roof, fast and cheap replacement for a damaged fixed steel roof, low cost tank maintenance, low weight design loads, rust-proof, low evaporation of fuel due to reflectivity of roof, etc., etc.).

If located in a safe place the tank can be made of wood, so why not an Aluminum roof (???). The radiation that receives a roof is very small (incident angle very small) and reflection makes it go pratically to cero, as to be a safe roof used for oil tanks, so why not for a water tank well located (???).

I´m not sure that the melting point of Aluminum is an issue, high conductivity makes Aluminium impossible to melt.