Tag: galvanic corrosion

LED Bridges and HRCSA

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Can LED beautification lighting projects lead to premature galvanic corrosion?

The corrosion of structural steel is an electrochemical process that requires the simultaneous presence of moisture and oxygen. Essentially, the iron in the steel is oxidized to produce rust, which occupies approximately six to ten times the volume of the original material. The rate at which the corrosion process progresses depends on a number of factors:

Micro-climate: In the photo above, this bridge is exposed to heavy de-icing salts during the winter. Due to multiple seasonal freezes, thaw cycles there is allot of moisture present which can migrate into the crevices. Result (electrolyte).

To avoid long term damage from crevice corrosion, these are the corrosion risks that could exist in LED lighting installed on steel bridges.

Examples of lighting fixtures applied to bridges.

From a corrosion mitigation point of view, these are the following corrosion risks that we see could exist in LED lighting installed on steel bridges.

LED lights fixture on a galvanized steel plate bolted directly to a carbon steel bridge frame.

Galvanic corrosion (also called bimetallic corrosion or dissimilar metal corrosion) is an electrochemical process in which one metal corrodes preferentially when it is in electrical contact with another, in the presence of an electrolyte. 

The aluminum plate interfaced to the copper plate and bolted with a carbon steel nut shows why you need electrical isolation.
Dissimilar metals braced together without insulation lead to corrosion.

Grounding example (dissimilar metals). Do lighting configurations operate on independent floating grounds?

How HRCSA Characteristics help manage LED light installation corrosion:

HRCSA is Non-conductive up to 100KV. Where HRCSA is applied as an electrical insulator between metals, HRCSA can impede the electrochemical process from taking place.

HRCSA Chemistry can insulate connections, so Corrosion has no place to start: The photo below represents BEST PRACTICE for fastening dissimilar metals together. HRCSA Penetrant/Sealer applied under pressure into gaps around the fastener shaft areas followed by a brush applied application of HRCSA self-priming topcoat both between the dissimilar plates as well as overtop the fasteners can help you achieve the same protection.

Repairs are fast & easy: Where existing installations show signs of dissimilar metal corrosion, HRCSA user-friendliness can put affordable and long lasting corrosion mitigation repairs within reach.

Applying HRCSA at the time of installation can be done with little effort.

Conclusion: When attaching dissimilar metals together, HRCSA is a user friendly cost effective alternative for preventing corrosion..