Case Studies

ID Localized Corrosion

Fast turnaround time


Millions of UT Readings

14.2M UT

UT Sensor

800 Readings Per
Boiler Tube Foot
(8610 per square meter)

Repair Insight

Spot Repairs

At the beginning of a 6-unit coal-fired power plant’s relationship with Gecko Robotics, plant personnel were struggling with the manual discovery of hydrogen damage brought on by ID Localized Corrosion. The localized corrosion, a specific type of corrosion called under deposit corrosion (UDC), and the one-by-one spot repairs addressing the hydrogen damage had proved unsuccessful in  delivering unit reliability. Despite repair efforts, widespread ID-side boiler tube damage caused numerous forced outages to address issues. Over the months before turning to robotic inspections, repairs would be made on the ID-side boiler tube corrosion discovered during manual  methods.  However, these repairs were unsuccessful at delivering unit reliability.

Gecko conducted a proof on concept robotic UT inspection on the waterwalls of Unit 6. This initial  inspection delivered annotated charts which identified boiler tube thinning amongst a section of the rear wall of the boiler. Data driven annotations, delivered in the proprietary Gecko Portal, helped pinpoint the locations of UDC by identifying small-scale defects frequently caused by this type of  corrosion. The defects are identified on the boiler tube by geolocating the tube, height, and angle of  the reading that revealed significant wall thinning. This type of thorough inspection accuracy was accomplished by gathering 800 readings per square foot (8610 per square meter) of boiler tube with the TOKA 3 Robot.

The proof of concept inspection results solidified, in the customers mind, that Gecko would provide the most comprehensive UT inspection with the fastest turnaround in the industry. Within the month, Gecko was hired to complete the inspection on the remainder of Unit 6. The inspection was completed in three days working around the clock with two robots and multiple NDT Level II Inspection Teams to collect data as quickly as possible during the plant outage. Twenty-four hours after the inspection was completed, Gecko delivered 50% of the results so that plant personnel could begin repair efforts on boiler tube problem areas. After an additional 24 hours, the remaining inspection results were delivered to the plant to complete the necessary repairs identified by the inspection. The deliverables included 3D Bokeh plots, Excel downloadables, and thousands of high definition images.

Before Gecko’s inspection data guided repair initiatives, maintenance teams would frequently discover, in as little as 24 hours, additional corrosion problems to boiler tubes that would force the unit to take an unplanned outage. Since thorough preventative maintenance measures were taken using  Gecko’s industry leading inspection data, Unit 6 has been able to stay online continuously for over seven months without an unplanned outage.

Localized corrosion on tubes

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