Ammonia and Aluminum

[rysep]

I work for a company that primarily makes parts out of C36000 Brass. We have a potential application in an indoor animal lot where ammonia will be an issue as well as plenty of moisture. From what I have researched so far ammonia and copper including brass are not compatible. Would an aluminum product be a viable alternative as far as corrosion is concerned? Either 2017-T4, T451 or 6061-T6 anodized. Stainless is an option also but may be prohibitively expensive.

 

[metengr]

rysep;
It looks like the 3XXX or 5XXX series aluminium alloys would work for your application (ammonia and urea). The heat treatable alloys normally don't have the corrosion resistance as the non-heatreatable alloys.

References;
ASM Handbook Volume 13 Corrosion
Corrosion Survey Database, by NACE International

 

[BenThayer]

the general rule of thumb is "no yellow metal" and so never use copper around ammonia. that i say after working at an ammonia, urea, nitric acid site for 18 years.

but we never had any corrosion to speak of at misc wiring and water valves in the barn where we had cattle and hogs. i say that after growing up on the farm for 18 years.

if there is no direct contact, the ammonia vapors in the air at a feed lot area may not be that significant. if you are talking about piping for moving wastes, that may be a different story.

we did lose some copper tubing in the ammonia unit near places where we had recurring leaks due to atmosphere.

aluminum for urea solution and about 500 ppm was used for misc storage tanks and can be fine. not sure about what grades they were.

 

[kenvlach]

I've seen some horse trailers of Al 6061-T6 with badly corroded floors. Any 2000 series Al would be worse; 3003, 5005, 5052 & similar would be better.