AFFF Storage tanks

[ledon]

I am trying to find a list of alternative materials approved for use in the construction of US Naval AFFF system fire fighting tanks. The drawing I currently have lists CuNi 90/10 for the entire tank.

 

[rpeng]

Ledon, The material specifications for each class of ship can be different; however AFFF piping for all ship classes I am familiar with must be 90-10 (MIL-T-16420). Different tank materials can be approved depending on the size of tank and ship class. I would consult NAVSEA directly, and check MIL-STD-777D. Occasionally, coatings can be used in lieu of CUNI materials.

 

[ledon]

Thank you for the response. I have reviewed Mil-Std 777E and it contains no information on the tank assembly, only piping and fittings. I have a call into the NAVSEA planning yard but have had no response yet. I was hoping that someone may know the Spec that these tanks are required to comply with.

 

[sjrfc2]

Mil-Std-777 is for piping. For AFFF use General Specifications for Overhaul, NAVSEA S9AA0-AB-GOS-010 where paragraph 555e1 states that construction of AFFF tanks shall be IAW NAVSEA (standard drawing) 803-5959273. The copy I have of that drawing is poor. It looks like General Note 5.H is where the copper-nickel requirement comes from. You could go with 70-30 if you were having a problem with 90-10. It looks like the note rules out CRES but that portion of my drawing is very poor quaility.

 

[mshimko]

Navy AFFF tanks were previously constructed from carbon steel. A few decades ago the standard drawing was changed to require 90-10 CuNi.

If you wanted to use 70-30 instead, I'm sure a deviation request would be approved, but it will cost more and provide no significant benefits.

 

[ledon]

The intent was to request CRES as an alternate, but it appears that may not be an option. While carbon steel tanks with rigid liners are often used in aviation and industrial applications, they were replaced aboard ships many years ago.

 

[mshimko]

Out of curiosity, what ship?

 

[ledon]

To classes of ship. LHD and AS

 

[sjrfc2]

Are you having trouble getting the material? Mil-C-15726 is commonly spec'd (UNS C70600). As a note, if alternative commercial forms/specs of the C70600 should be approved prior to starting the work to ensure there are no welding issues with the material. It looks like the SAE cross ref book for UNS calls out limits on carbon, zinc, phosphorus, lead and sulfur when the product is for subsequent welding applications.

thanks for the background mshimko.

 

[ledon]

Material is a minor issue. I was detailed to research alternative materials partly based on that and partly based on time constraints. Although the job has since been pushed out. So time is no longer such a factor.