Why Grating Rusts At The Cut End

Look At Where The Rust Is

Rust in the middle of a bearing bar is rare. Rust at a cut end, at a hook weld, around a drilled hole or along a banding bar is common, and all four have the same cause: the steel was exposed after it was coated.

Coat Last, Not First

A panel cut, drilled, hooked and banded before galvanizing comes out of the bath covered everywhere. A pre-galvanized panel that is then cut on site has bare steel at every cut, and that is where it starts.

Site Cutting Is The Usual Culprit

Flame cutting a galvanized panel destroys the coating well beyond the cut, and few site repairs come close to the original protection. Panels are better cut and banded before coating, which is why panel sizes are drawn rather than trimmed.

On Stainless It Is The Same Logic

The equivalent failure is skipping passivation after fabrication, or using tooling that has touched carbon steel. The rust that appears is often not the panel corroding at all, it is embedded iron particles rusting on its surface.

What To Do With An Existing Run

Assess where the rust actually is. Isolated cut-end failures can be replaced panel by panel, and matching a replacement to an existing run is routine from photographs and measurements.