Corrosion Resistance of Maintenance Equipment

Question:

What should be done to improve the corrosion resistance of the products we sell that are used to maintain golf courses, institutional grounds, parks and airports? We currently specify ASTM B-633 Class Fe/Zn 5 with a Type II finish.

Answer:

The products you described are more than likely exposed to watering systems. Fe/Zn 5 in ASTM B-633 requires a zinc thickness of only 5 micro meters (0.0002 in.). For steel articles frequently exposed to rain or highly humid environments, a zinc thickness of 25 micro meters (0.001 in.) is recommended. The ASTM B-633 classification for this coating is Fe/Zn 25. Also suggested is an olive drab chromate conversion coating, which is better than a yellow, Type II coating. A "clear" or "blue" chromate coating supplies even less protection.

Chromate-treated zinc-nickel and zinc-cobalt alloy deposits are better than unalloyed, chromated zinc electroplated coatings. Ask your vendors to request information from their suppliers on these zinc alloy plating processes.