Boilers suffer from many forms of degradation while in service. Water Wall tubes can suffer from Hydrogen Damage, pitting, ash and soot-blower erosion, graphitization, under-deposit corrosion, thermal fatigue cracking and creep damage. All of these defects can be detected by use of a fast robotic system known as VertiScan
The VertiScan System is used to rapidly scan the water walls of a boiler during an outage so that repair decisions can be made proactively.
Up to five tubes are scanned at once, at speeds up to 5m (15')/min The robotic (TubeCATTM) crawler can climb 100' up/down the water wall and handle up to 1/4" of scale between the tubes.
Results are presented immediately on a colour map showing areas of degradation. The cost to scan all four walls of a boiler is generally far below the cost of an emergency shut-down due to a tube failure.
All indications found are checked with visual and ultrasonic techniques where tubes are accessible.
Acknowledgements:
The VertiScan System was developed by the following Russell NDE Systems staff:
- Nabil Makari, P. Eng.
- Hoan Nguyen
- Derek Brent
- Ankit Vajpayee, P. Eng.
- Ellen Jin
- Yuwu Yu, PhD
Jireh Industries modified their tank wall crawler to "fit" the application of boiler water wall tube inspection. After modification the crawler was named "Tube-CAT"