Use the structure as the location system
Describe corrosion against member marks, grid lines, levels and connection references rather than a collection of unlocated photographs. Identify the flange, web, face or connection region involved. The map should distinguish apparently affected areas from surfaces that were not accessible.
A structural steel inspection can record condition and targeted examination evidence. Provide available drawings and explain whether the work supports maintenance planning, investigation of a particular member or a wider condition review. Mapping condition is not the same as establishing structural capacity.
Describe appearance without assuming loss
Coating breakdown, rust staining, scale, pitting and apparent section loss describe different observations. Record their visible extent and location separately. A large stained area may not have the same depth of loss throughout, and heavy scale can conceal the remaining metal surface.
Photograph the wider member and the local feature before preparation. Where cleaning exposes different condition, retain both views and identify the preparation. Avoid estimating remaining section solely from rust volume or colour; measured thickness or other examination may be needed.
Choose targeted measurements for the damage pattern
Agree measurement locations based on observed condition and likely damage mechanisms, including sheltered crevices, water traps or connection interfaces where relevant. Fixed grid points can support repeat surveys, but concentrated local damage may need additional examination between them.
Thickness measurements depend on access, geometry and surface condition. Original section dimensions may also be uncertain on older assets. Keep measured values distinct from assumed nominal dimensions, and flag places where scale, curvature or lack of access prevents reliable readings.
Show extent and uncertainty together
A findings register can combine member identity, affected surface, mapped extent, photographs, readings and limitations. Use a clear legend if condition categories or colour codes are applied. Those categories should not silently become capacity ratings or an assurance that an uncoloured area is sound.
Connections need particular location detail: corrosion at a plate edge, around a fastener and in a concealed interface can have different implications. Where an interface is not exposed, label it unexamined. The map should show the boundary of evidence, not fill the unknown area with a uniform condition assumption.
Hand over evidence for maintenance and engineering
For an ageing beam, the engineer may need the distribution of loss across the section, loading information and connection condition rather than a single minimum thickness. A maintenance team may need coating preparation boundaries and access requirements. Explain these different needs when commissioning the survey.
Preserve the map for repeat visits and record replacements or changes to member identifiers. Any decision about strengthening, replacement or use requires the appropriate assessment. The inspection map provides located evidence; it does not by itself determine a repair design or authorise loading.