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Boilers

Inspection of Boiler Water Wall tubes using VertiScan™ System

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.

VertiScan System



VertiScan typical data, including CCTV image

Placing the crawler on the wall (above and below)

VertiScan typical data, including CCTV image

Foreground computer: data, Background: CCTV

Placing the crawler on the wall



BOILER TUBE TYPICAL DEFECTS

AS DETECTED BY VERTISCAN SYSTEM

BOILER TUBE TYPICAL DEFECTS

Internal pitting at weld

BOILER TUBE DEFECTS

Internal Graphitization (under-scale pitting)



Thermal Fatigue Cracking

Thermal Fatigue Cracking

Local Ash erosion

Local Ash erosion



Blisters and pinhole leaks

Blisters and pinhole leaks

Fishmouth failure (above) cause by Hydrogen damage

Fishmouth failure (above) cause by Hydrogen damage

Hydrogen Damage

Hydrogen Damage



Literature