T Scan

Corrosion Mapping

Applus RTD offers many methods for non-intrusive corrosion detection. Most give average or spot thickness measurements and have the advantage of speed. Only Thickness-Scan™ corrosion mapping provides precise measurement and a virtual picture of the damage.

Automated UT corrosion mapping can produce precise, repeatable images displaying corrosion damage in top and sectional views. Images are analysed dynamically to determine pit diameter, depth and distribution. Repeated surveys allow comparison of images and thickness data to determine corrosion rates.

Corrosion mapping surveys are useful both for an initial assessment and long-term monitoring of damage. It also complements our rapid scan techniques such as Incotest, Long Range UT, Handscan and Pipescan. Corrosion detected by these screening techniques is readily quantified by applying corrosion mapping to areas of concern.

Brief Description

Corrosion data is collected by a Force AWS 5 motor driven scanner attached by magnetic wheels or a steel track for non-ferrous materials (MBI have access to additional scanners supplied by the Force Institute). The scanner increments along its main axis (X-direction) as it scans one or more UT probes laterally over the material surface (Y-direction). UT data is collected continually to build a complete ultrasonic image of the area scanned.

The scanner is controlled by the main processing unit (P-Scan), usually housed in a small trailer. An umbilical cable (50m) carries couplant (water) for the probe, power, control signals and ultrasonic and probe position data. Scan rates and resolution are controlled by the operator via the main control unit.Scan speed depends on resolution and other requirements, rates of 6 sq metres per hr can be achieved on unobstructed areas.

Stored thickness readings are displayed using T-Scan™ software. This shows any corrosion damage in top and side views. Cursor and level controls allow the operator to evaluate corrosion damage and extract thickness information from any point on the display. Statistical output from the software is useful for monitoring corrosion rates or growth of blistering and other laminar defects (HIC).

Scan results are reported with both colour images and tabulated thickness values. These may be compared with previous data sets. The scan images are colour coded for thickness and provide an excellent view of corrosion damage and its progression.

Capabilities

Uses commercially available focussed ultrasonic probes. The probe is selected to suit the material type, thickness and resolution requirements.
Can use angle beam probes for additional information about defect orientation and geometry.
Non-intrusive, measurements from the outside surface.
Suitable for ferrous and non-ferrous materials.
Highly repeatable with an accuracy of ± 0.1mm, established with over 12 years of experience in the petrochemical industries.
Echo to echo capability eliminates the effect of coatings.
Works on 75mm diameter pipe up to flat plate.
Single scan widths up to 700mm
Temperature range 0 - 90oC
Easily understood images of damage including top and sectional views. Data stored for comparison with future surveys.

Preparation

Test surfaces must be free of rust, scale, spatter and other contaminants that impede ultrasonic coupling. Well-bonded paint is usually acceptable.

Services Required