Corrosion Protection of Residential Wrought Iron Fence_02

[PnP_Eng44]

I have a similar situation as posted in thread338-42599 - I have an iron fence mounted in a low cement wall that borders on a park. The park uses sprinklers nightly with treated water. After one year, the fence is showing significant corrosion where it enters the concrete and light corrosion elsewhere. Would it help to paint the fence with a zinc primer and screw on Mg anodes? Will grounding the fence impact the corrosion?

 

[SJones]

The zinc rich paint IS the sacrificial anode. Unfortunately, to work effectively, it requires the optimum surface preparation which is unlikely to be achieved in such an application. Thus, a more surface tolerant paint will be required which should contain corrosion inhibiting additives, such as zinc phosphate. Note: this is barrier formation and inhibition, not cathodic protection. Discrete sacrificial anodes will only work with a continuous water film, and will have a tendency to passivate (i.e. malfunction) owing to the dry periods that they may experience in air on the fence. Focus on finding a good paint from a reputable manufacturer that will tolerate the surface preparation that you are able to apply, most likely sanding and wire brushing, can be applied by the technique that you are able to use, most likely brushing, and contains inhibiting additives. Apply as directed, including any UV resistant overcoating, and maintain by touch up as required.

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/in/drstevejones

All answers are personal opinions only and are in no way connected with any employer.

 

[Dhurjati Sen]

But as a lesson learnt, go for shop painted fences in future.

DHURJATI SEN