What is corroded condition?
Metal being eaten away by chemical or electrochemical attack — rust, deposits, pitting and seized fixings — and how an inspector decides how far it has gone.
Corroded condition means the metal of an asset is being chemically or electrochemically attacked, taking it away from its design baseline. It shows as red rust on steel, white or grey powder on aluminium and zinc, green deposits on copper and brass, pitting, flaking coatings and seized or rounded fixings.
Corrosion is progressive: it keeps going until its cause is removed. Moisture, de-icing chemicals, salt air, dissimilar metals in contact and failed coatings are the usual causes. Surface corrosion is cleaned, protected and monitored. Corrosion that removes material or impairs function is repaired or replaced. Corrosion of an earth bond, a current-carrying contact or a structural or break-away part is critical and made safe first.
Slow, progressive chemical attack on the metal. It continues and spreads until the cause is found and removed, so treating only the visible part is not enough.
Sudden physical harm such as a crack, cut or crush. It is usually tied to an event and does not spread by itself.
- Make the area safe. Work under the permit-to-work. Do not assume a corroded part is isolated or dead.
- Photograph as found. Before cleaning, with date and location, so progression can be compared next cycle.
- Identify the type. Rust, white or green deposits, pitting, flaking, seized fixing.
- Find the cause. Moisture, chemicals, dissimilar metals, failed coating or stray current.
- Judge the extent. Surface only, or material lost? Does it affect contact, earth continuity, sealing or strength?
- Classify and act. Surface, progressive or critical, then clean, protect, repair, replace or make safe, and fix the cause.
Frequently Asked Questions
Q1What does corroded condition mean in AGL inspection?
An asset whose metal is being eaten away by chemical or electrochemical attack, showing as rust, white or green deposits, pitting, flaking or seized fixings. It is recorded, classified by how far it has progressed and what it affects, and acted on according to the site's procedures.
Q2How is corrosion different from damage?
Damage is sudden physical harm such as a crack, cut or crush. Corrosion is a slow, progressive process that keeps going until its cause is removed. A cracked housing is damaged; a housing that has rusted through is corroded.
Q3What causes corrosion on airfield lighting?
Moisture, de-icing chemicals, salt-laden coastal air, dissimilar metals in contact, stray current and failed protective coatings. Finding and fixing the cause matters as much as treating the corroded part, or the corrosion returns.
Q4What does corrosion look like on different metals?
Steel goes red-brown and flakes. Aluminium and zinc-coated parts show white or grey powder and pitting. Copper and brass show green or blue-green deposits. A seized or rounded fastener is often the first sign.
Q5How is corrosion classified?
By how far it has gone and what it affects. Surface corrosion does not reduce the strength or function of the part and is cleaned, protected and monitored. Progressive corrosion has started to remove material or impair function and is repaired or replaced. Critical corrosion affects safety, such as an earth bond, a current-carrying contact or a structural or break-away part, and is made safe first. The exact grading comes from the site's inspection procedure.
Q6Why are corroded connectors and earth bonds a concern?
Corrosion raises contact resistance, which can cause heating, intermittent faults or arcing in a series circuit, and a corroded earth bond may no longer protect people or equipment. Both can be safety-critical even when they look minor.
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