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Gridbots Magneto-TUBESCAN

Boiler Tube Thickness Mapping Robot

Magneto-TUBESCAN is a magnetic climbing robot built to measure the wall thickness of power plant boiler waterwall tubes – up to 10 tubes in a single run – using an array of immersion ultrasonic probes.

As it climbs the waterwall, every probe records tube thickness continuously at 0.1 mm linear resolution with ±0.1 mm measurement accuracy. The data is stitched in real time into a 3D thickness map of the boiler that clearly marks healthy tubes, sections to monitor, and critical thinning that needs replacement.

Permanent-magnet adhesion, twin PMSM drives, an encoder and a 6-DOF IMU let the robot climb vertical and inclined waterwalls while knowing exactly where every reading was taken – so each thin spot can be found again for repair.

TUBESCAN replaces scaffolding and slow manual spot-gauging, cutting boiler outage time and giving plant engineers complete, traceable tube condition data for every shutdown.

Magneto-TUBESCAN scanning boiler waterwall tubes

Tubes per run

0.1 MM

Linear resolution

±0.1 MM

Thickness accuracy

Boiler thickness map

OPERATOR CONTROL UNIT

The 12” touch-screen operator control unit drives the robot and runs the TUBESCAN mapping software. It shows live camera video, the A-scan of each probe, a running thickness trace for all 10 tubes and the robot’s position on the waterwall.

As the robot climbs, readings are colour-coded against your nominal and minimum allowable thickness, so critical spots appear on screen the moment they are scanned. At the end of each run the data joins the boiler’s 3D map, and a report with tube-by-tube results is generated automatically.

Ultrasonic Thickness Measurement

Ultrasonic testing sends a short, high-frequency sound pulse into the tube wall. The pulse reflects from the inner (water-side) surface and returns to the probe. Because sound travels through steel at a known, constant velocity, the time it takes for the echo to return gives the exact remaining wall thickness – measured from outside the tube, with no cutting and no access to the inside.

Thickness = (Velocity in steel × Echo time) ÷ 2

Typical longitudinal velocity in carbon steel ≈ 5,920 m/s. A 6.0 mm wall returns its echo in about 2 microseconds.

Immersion Probe Array on Waterwall

Cross-section: one water-filled probe shoe on each tube crown

Each probe sits in a water-filled shoe that follows the tube crown, giving perfect acoustic coupling without gel and without touching the tube.

A-Scan: Reading the Echo

Signal from one probe as seen on the controller

Echo-to-echo measurement between successive back-wall echoes cancels the water path and any oxide layer, giving true metal thickness.

Immersion Coupling

Water-filled shoes couple sound into the tube with no gel and no wear, so readings stay stable across rough, scaled tube surfaces.

10 Channels at Once

One probe per tube crown measures ten tubes simultaneously in every climb – ten times the coverage of single-probe gauging.

Position-Tagged Data

Encoder and IMU tag every reading with tube number and elevation to 0.1 mm, so any thin spot can be located for repair.

3D Thickness Mapping

Every run is merged into a 3D model of the boiler waterwall. Each tube is colour-coded along its full height, so engineers can see at a glance which sections are healthy, which need to be watched, and which are critical – and plan tube replacement before a failure forces an unplanned outage.

3D Tube Condition Map

10 tubes × 6 m elevation, nominal wall 6.0 mm

OK ≥ 5.4 mm Monitor 4.8–5.4 mm Critical < 4.8 mm

2D Thickness Map (Unrolled)

Same scan – continuous colour scale, tube number vs. elevation

4.0 mm

6.2 mm

Thickness Profile Along Tube

Tubes 3, 6 and 9 – continuous 0.1 mm-step readings (sampled for display)

Minimum Thickness per Tube

Lowest reading found on each tube in this run

Condition Distribution

Share of scanned tube length in each condition class

Accuracy vs. Reference

TUBESCAN readings vs. calibrated reference on test tubes

CONDITION CLASSIFICATION

Class	Remaining Wall	Example (6.0 mm nominal)	Recommended Action
OK	≥ 90% of nominal	≥ 5.4 mm	No action – re-scan at next scheduled outage
MONITOR	80 – 90% of nominal	4.8 – 5.4 mm	Trend at every outage, check for erosion source
CRITICAL	< 80% of nominal or below t-min	< 4.8 mm	Pad weld or tube replacement before restart

Thresholds are fully user-configurable to match your boiler design code, tube material and plant standards.

SAMPLE RUN REPORT

Tube	Min (mm)	Avg (mm)	Min at Elevation	Wall Loss	Status

Maps, charts and the report show representative data for illustration. Real results come from your boiler scan.

Features

Measures up to 10 boiler tubes in a single run

Immersion ultrasonic probes – no gel, no contact wear

0.1 mm linear resolution, ±0.1 mm accuracy

3D boiler map with OK / Monitor / Critical zones

Real-time inertial tracking (6 DOF)

Climbs straight and inclined waterwalls

Permanent magnet adhesion, all wheels power driven

3 FHD cameras for visual tube inspection

Outage-to-outage trend comparison

Up to 250 m umbilical – operate from outside the furnace

Applications

Coal-Fired BoilersWaterwall erosion from soot blowers, burners & fly ash

CFBC BoilersRefractory-interface and bed-zone tube wastage

Biomass & WtE BoilersCorrosion from chlorides and aggressive fuels

Recovery BoilersPulp & paper recovery boiler wall tubes

HRSG & Utility BoilersMembrane wall panels and water-cooled surfaces

Life AssessmentRLA studies & outage planning with trend data

INSPECTION WORKFLOW

PrepareLight surface cleaning; set nominal & t-min

ScanClimb 10 tubes per run with live readings

MapRuns merge into the 3D boiler model

ActReport critical tubes with exact location

TUBESCAN vs. MANUAL UT GAUGING

Parameter	Manual UT with Scaffolding	Magneto-TUBESCAN
Access	Full furnace scaffolding	Magnetic climbing – no scaffolding
Tubes per pass	1	10
Data density	Spot readings, typically every 0.5 – 1 m	Continuous, every 0.1 mm
Coupling	Gel, operator dependent	Immersion water column, consistent
Location accuracy	Hand-marked, approximate	Encoder + IMU tagged
Output	Paper sheets / spreadsheet	3D map, trend overlay & auto report
Risk of missing thin spots	High between spot readings	Very low – full-length coverage

Specifications

ROBOT

Model Series	GB-MAGNETO-TUBESCAN
Power Drive	Twin 400 Watts PMS Motors
Adhesion	Permanent Magnets
Robot Adhesion Force	Up to 500 N
Robot Line Speed	Up to 20 mm/second
Position Tracking	Wheel Encoder + 6 DOF IMU
Linear Resolution	0.1 mm
Cameras	3 FHD with LED Illumination
Robot Power Consumption	100 W (Average)
Supply Type	Single Phase A.C. / Battery Pack
Robot Self Weight	20 kgs
Supply and Sensor Interfacing	Via Umbilical Cable
Cable Length	Up to 250 Meters
Operator Control Unit	12” Touch Screen Tablet PC

ULTRASONIC SYSTEM

Technique	Immersion Pulse-Echo, Echo-to-Echo Mode
Channels	10 (one per tube) in a Single Probe Beam
Tubes per Run	Up to 10
Probe Frequency	5 – 10 MHz
Coupling	Water Column in Self-Aligning Probe Shoes
Thickness Range	2 – 15 mm (steel)
Measurement Accuracy	±0.1 mm
Display Resolution	0.01 mm
Tube Outer Diameter	38 – 76 mm (probe shoes per tube size)
Tube Pitch	Adjustable Probe Spacing to Match Waterwall Pitch
Calibration	On-site Step Block, Velocity Auto-Calibration

MAPPING SOFTWARE

Live Views	Camera, A-Scan per Channel, 10-Tube Thickness Trace
Maps	3D Boiler Model, 2D Unrolled Waterwall Map
Classification	OK / Monitor / Critical – User-Set Thresholds
Boiler Layout	Wall, Tube Number & Elevation Referencing
Trending	Overlay of Previous Outages, Wear Rate per Tube
Export	PDF Report, CSV / Excel, 3D Model Snapshot

SAFETY

TOF Sensors	6x
Impact Sensor	1x
E-Stop	2x
Fall Arrest	Safety Rope Anchor

ENVIRONMENTAL

IP Rating	54
Temperature	5°C to 65°C
Humidity	95%, Non-Condensing

Gallery

On the Waterwall

10-Channel Probe Beam

3D Thickness Map

Complete System

Drawings

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