# Corrosion mapping

> Corrosion mapping is an encoded ultrasonic scan of a defined area that records thickness at every point and presents it as a colour-coded C-scan image, showing the extent and pattern of internal corrosion or erosion.

- Source: https://amps.global/glossary/corrosion-mapping/
- Type: Glossary
- Published: 2026-09-05
- Tags: NDT, ultrasonic testing, corrosion, advanced NDT

## Key facts

- Semi-automated (manual scanner with encoder) or automated (motorised crawler) with single or phased array probes
- Detects isolated pitting, general wall loss and hydrogen damage that spot thickness readings can miss
- Data feeds fitness-for-service assessments under API 579-1/ASME FFS-1
- Coverage, resolution and calibration are stated in the procedure and the report

Also known as: UT corrosion mapping, C-scan mapping, automated corrosion mapping.

## How it works

The probe is moved over the surface in a grid or raster while an encoder records position. Each position holds a thickness value, and the resulting map makes the minimum thickness, its location and the corrosion pattern obvious. Repeating the scan later shows how the damage evolves.

## Where it is used

Vessel shells and nozzles, tank shells and annular plates, piping elbows and dead legs, and any area where a spot survey found unexpected loss.

## Corrosion mapping in AMPS

Scan data files and the Word report are stored with the job in your own OneDrive, SharePoint or Google Drive through AMPS, and the asset's job history keeps successive maps together. All AMPS data is available to Power BI, which is how customers compare job or shutdown performance, costs and time allocation.

## Related pages

- [Ultrasonic thickness gauging](https://amps.global/glossary/ultrasonic-thickness-gauging/)
- [Phased array UT (PAUT)](https://amps.global/glossary/phased-array-ultrasonic-testing/)
- [Asset integrity management](https://amps.global/glossary/asset-integrity-management/)

## Sources

- [Ultrasonic testing on Wikipedia](https://en.wikipedia.org/wiki/Ultrasonic_testing)
- [API - American Petroleum Institute standards](https://www.api.org/products-and-services/standards)