Thickness Mapping of Boiler Tubes with EMAT



Thickness Mapping of Boiler Tubes with EMAT We offer this service using temate TG-IS (B) which is a redesigned FST-GAGE or Fast Scanning Thickness Gage, first introduced in 1994. FST-GAGE was developed by Electric Power Research Institute (EPRI) and Babcock & Wilcox (B&W) specifically to scan boiler tubes and provide a continuous measurement of tube wall thickness.


The system works on ultrasonic EMAT (Electro Magnetic Acoustic Transducer) technique providing accurate thickness (with accuracy of +/- 0.127mm) readings with none or minimal tube surface preparation. The probe with integrated encoder and light indicators (for fast visual alert to the operator) is manually scanned along the boiler tube while the system records the thickness & alarms if the tube is below a pre-programmed threshold or other defect conditions are triggered. The system saves a complete record of each tube & the whole boiler for later post analysis & tracking.


Apart from detecting wall loss the system is capable of detecting hydrogen damage, pitting & caustic gouging (by measuring signal attenuation) which is not detected with conventional means. It works on carbon steel and clad tubes. Tube thickness ranges from 3.8mm to 12.7mm & the minimum tube diameter requirement is 22.2mm, the tube surface can be oxidized, rough or pitted (scale-free).

The technique permits 100% inspection of the boiler instead of spot checking at up to 15cm/s of scanning speed. The boiler mapping tool permits easy visualization of boiler walls with results of inspection for fast analysis and interpretation.