Rust is the result of oxygen and moisture bonding with the iron in steel. The oxidized layer continues to feed off the iron beneath it as long as there is oxygen and moisture present. Since steel is often used in construction, steps have to be taken to slow or prevent the rust from happening and weakening the underlying surface.
The pictures here show steel beams that have holes rusted through them. These photos were taken in an electrical vault that was improperly primed. If the beams had collapsed, the results would be deadly. Fortunately, the situation was discovered and remediated before that could happen.
There are several ways to remove existing rust and depend on the area where the work is performed. Wire brushes are great for hard to reach areas and tight spots. Media blasting works well in situations where the media can be recovered and there is ventilation. Acid baths are good for pieces that can be soaked for extended periods of time.
Once the rust is removed, the surface needs to be inspected. If there isn’t enough salvageable metal left, then entire sections need to be replaced. The idea here is to have a finished product that is as strong or stronger than it was when it was new.
For sections where there is enough steel remaining, the surface need special treatment. This is because rust is difficult to completely eliminate. Rust inhibitors help keep the rust from returning while encapsulating primers form a tight seal around the steel. Once the entire area is thoroughly primed, the final coatings can be applied.
Routine maintenance, such as inspections and cleanings can go a long way to making sure steel structures aren’t showing signs of rust. If blistering, pockmarks or other indications of rust appear, it’s time to strip off the old coatings, repair the issues and recoat.