Robotic NDT • Recovery & black liquor boiler inspections • Pulp & paper

Robotic wall-thickness inspections for recovery & black liquor boilers.

RESTinspect replaces limited manual UT campaigns with high-density robotic wall-thickness inspections across recovery boiler wall sections. The result is not just more measurement data, but a complete inspection picture in the RESTinspect Portal, where teams can review findings through interactive 2D and 3D views instead of relying on isolated readings.

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From limited readings to a complete inspection picture.

In recovery and black liquor boilers, the risk is not just thinning itself, but missing where it is developing. Manual UT campaigns often produce too little coverage and too little context to support confident maintenance decisions during short outages.

RESTinspect combines robotic high-density wall-thickness inspection with a dedicated portal that makes the results usable. Our crawler captures dense measurement data across the inspected wall sections, while the portal turns that data into interactive 2D and 3D views, visual overlays, detailed point information and a clear inspection history.

That means your team does not just receive more measurements. You get a far better view of where thinning occurs, how it is distributed across the boiler section and how findings compare over time, so outage scope and repair priorities can be set on evidence rather than assumptions.

High-density UT data Interactive 2D/3D portal views No scaffolding Better outage decisions

Our solution: robotic inspection connected to a usable portal.

NURA is RESTinspect’s robotic crawler for autonomous, high-density ultrasonic wall-thickness inspections inside industrial boilers. For pulp & paper mills, it is configured for the access, geometry and outage constraints typical of recovery and black liquor boilers.

The crawler captures wall-thickness data at resolutions down to 5 mm spacing and delivers 0.1 mm-level thickness values across complex furnace geometries. It supports both ferromagnetic membrane walls and non-ferromagnetic tubes, making it suitable for consistent inspection campaigns across multiple boiler sections.

But the value does not stop at acquisition. All inspection results are organised in the RESTinspect Portal, where engineers and maintenance teams can review interactive 2D and 3D views, compare inspections, inspect local details and work from a clearer picture of asset condition.

Its modular design adapts to different wall types, tube pitches and local constraints, including dense tube arrays with pitches down to 6 cm, while the portal provides the context needed to turn raw measurements into practical maintenance decisions.

High-density UT Interactive portal 2D and 3D inspection views Modular platform

Robotic inspection on black liquor recovery boiler lower furnace waterwall

Lower furnace & char bed walls

High-density inspection of lower furnace waterwalls, where heat load, deposits and chemical exposure can create highly local damage patterns that are difficult to understand from limited spot readings alone.

Identify local minima across the inspected wall area
Review critical areas in visual inspection views
Support targeted repair decisions

Robotic inspection on large CTC spacing and flat surfaces

Large CTC spacing & flat surfaces

For wider tube spacing or flatter sections, the robotic setup can be adapted to maintain dense inspection coverage while keeping the results available in the same portal structure and visual workflow.

Flexible configurations for varying CTC distances
Efficient scanning of wider or flatter surfaces
Consistent outputs across different inspection geometries

Inspection of upper furnace and screen tube area in a recovery boiler

Upper furnace & screen tubes

Upper furnace and screen-tube areas can show irregular thinning caused by deposits, thermal cycling and flow effects. These sections can be mapped as part of the same campaign and reviewed in one connected inspection environment.

Continuous data across multiple boiler zones
Point-level details with visual context
Clearer comparison between inspected areas

How it fits into your mill outage

Our service combines robotic inspection, structured data handling and portal-based review into one workflow that fits the realities of a planned mill shutdown.

After mobilisation and site safety preparation, the robot is introduced into the boiler and scans the selected sections at high spatial resolution. Measurement data is captured in structured datasets with full traceability and prepared for review in the RESTinspect Portal.

Once the inspection is complete, your maintenance, reliability and engineering teams can review results through interactive 2D and 3D views, inspect local thickness details, compare findings and use the portal as the working environment for outage follow-up.

Turnkey inspection service Built around outage planning Portal access for stakeholders

Supporting pulp & paper producers worldwide

RESTinspect supports pulp & paper producers, OEMs and engineering partners across multiple regions. Our inspection approach is designed to fit within existing outage routines, safety requirements and plant workflows while making results easier to use after the inspection itself.

Whether you operate one recovery boiler or multiple black liquor boilers across different sites, the objective stays the same: better inspection visibility, clearer maintenance follow-up and fewer decisions based on incomplete information.

Europe Africa Asia South America Worldwide deployments

Ready to inspect your recovery / black liquor boiler walls?

RESTinspect helps pulp & paper mills collect high-density inspection data and review it in a portal built for engineers, maintenance teams and outage follow-up.

Discuss your next recovery boiler outage