A climbing inspection robot is a crawler platform that holds itself against a vertical or overhead surface so it can carry an inspection payload somewhere a person would otherwise need scaffolding, rope access, or a confined-space entry to reach. There are two fundamentally different ways these robots generate the force that holds them to the surface: magnetic adhesion, and non-magnetic adhesion (vacuum, suction, or a suction-and-airflow hybrid). Which one a given robot uses determines almost everything else about where it can and can’t be deployed.
In this guide we cover how each type works, where each is used, the honest limitations of both, and what a robotic inspection deployment actually looks like in practice, from mobilisation through to the data you get back.
Type 1: Magnetic adhesion crawlers
Permanent or electro-permanent magnets in the robot’s wheels or tracks hold it to a ferromagnetic (iron- or steel-containing) surface. It’s a strong, reliable holding force that, in many designs, doesn’t need continuous power to maintain, which is one reason magnetic crawlers are common on ship hulls, steel tanks, and pipework. AKA Robotics’ WallHiker range is a well-known example, built specifically for ferromagnetic surfaces like ship hulls, and able to adapt to curved surfaces and cross weld seams and other obstacles.
The limitation is inherent to the technology: magnetic adhesion only works on ferromagnetic metal. It can’t be used on concrete, brick, aluminium, composites, or most tank-grade stainless steel — common grades like 304 and 316 are austenitic and non-magnetic, so a magnetic crawler simply has nothing to grip.
Type 2: Non-magnetic adhesion (vacuum, suction, and suction-and-airflow)
Instead of magnets, these robots generate a holding force using negative air pressure (vacuum), suction, or a combination of suction and directed airflow, regardless of whether the surface is magnetic. Invert Robotics is a well-known example, using patented vacuum adhesion technology to move across smooth magnetic and non-magnetic surfaces including stainless steel, aluminium, and plastic — which is also why vacuum-based platforms are common in industries like food and beverage, where most tanks and vessels are non-magnetic stainless steel.
Classic pure-vacuum systems generally need a relatively smooth, sealable surface to hold a reliable vacuum, which is why they tend to be used on tanks and vessels rather than rough or uneven structures. A more recent development combines suction with directed airflow rather than relying on a pure vacuum seal. HausBots’ AEROGRIP technology works this way: a suction-and-airflow hybrid generating continuous downforce — around 350N on the HB2, up to 1000N on the HB3 — that holds the platform to a surface without needing a magnetic material or a smooth, sealable surface. That’s what lets the same platform climb rough surfaces like concrete and brick, as well as smooth stainless steel, aluminium, and composites
| Dimension | Magnetic adhesion | Vacuum / suction-and-airflow adhesion |
|---|---|---|
| Surface compatibility | Ferromagnetic metals only | Ferrous and non-ferrous surfaces |
| Surface texture | Smooth or moderately rough metal | Pure vacuum: generally needs smooth, sealable surfaces. Suction-and-airflow hybrids (e.g. AEROGRIP): also handle rough surfaces like concrete and brick |
| Power draw | Often lower continuous draw | Continuous power needed to maintain suction/airflow |
| Typical use cases | Ship hulls, steel tanks, pipework | Tanks, silos, concrete structures, mixed-material sites |
How to choose between the two types for your site
In practice, the decision usually reduces to one question: is every asset you need to inspect ferromagnetic steel, or does your site include concrete, brick, aluminium, composites, or non-magnetic stainless steel? If it’s the former, a magnetic crawler is a proven, power-efficient choice. If your site is mixed, or includes any non-ferrous structure, a suction-based platform is the only option that will work across all of it — and a suction-and-airflow hybrid is the only one of those that will also handle rough surfaces like concrete rather than just smooth tanks.
Energy & Nuclear
Sites mix steel pressure vessels with reinforced concrete cooling towers and containment structures.
- Magnetic crawlers can cover steel turbine halls and pipework
- Concrete cooling towers and containment structures need non-magnetic adhesion
- A single suction-and-airflow platform can move between both surface types on the same site
Oil & Gas
Storage tanks are typically carbon or stainless steel, but composite (FRP) linings are increasingly common.
- Carbon steel tank shells suit either adhesion type
- FRP-lined or composite tanks rule out magnetic adhesion entirely
- Suction-and-airflow avoids needing two different robots for the same tank farm
Water
Digesters, water towers, and pipework are frequently concrete or non-magnetic stainless steel.
- Concrete digester tanks (see our Digester Tanks case study) require non-magnetic adhesion
- Non-magnetic stainless steel is common in treatment infrastructure
- Rough concrete surfaces need the airflow-hybrid approach, not pure vacuum
Cement & Quarrying
Silos and kilns are predominantly concrete and steel in combination.
- Concrete silo shells rule out magnetic-only crawlers
- Steel conveyor gantries and supports can suit either type
- Rough, weathered concrete surfaces favour a suction-and-airflow platform over pure vacuum
Chemicals
Reactors and pipework are commonly stainless steel; some structures are concrete-housed.
- Non-magnetic stainless steel reactors and vessels need suction-based adhesion
- Mixed sites with concrete secondary containment need surface-agnostic platforms
- Hygienic surface finishes on some vessels favour smooth, residue-free adhesion methods
Food & Beverage
Tanks and vessels are almost universally non-magnetic stainless steel for hygiene reasons.
- Fermenters, mixing vessels and storage tanks are typically 304/316 stainless — non-magnetic
- Magnetic crawlers are rarely viable in this sector for that reason
- Vacuum and suction-and-airflow platforms dominate food-grade vessel inspection
Honest limitations of suction-and-airflow crawlers
Suction-and-airflow platforms aren’t universally superior — they trade the passive holding force of magnets for continuous power draw, which is a real design cost. Very porous or heavily degraded surfaces can also reduce the efficiency of any suction-based system, magnetic or otherwise, and extremely tight geometries may still be better served by a smaller, purpose-built platform. As with any climbing system, deployment should follow the site’s own working-at-height and rigging protocols.
What you get: reporting & deliverables
Regardless of adhesion type, a crawler robot is a delivery platform for an NDT payload — the deliverable you receive depends on that payload (see our NDT Payloads Explained guide), not the adhesion method. Typical outputs include a PDF summary report, raw sensor data (thickness readings, corrosion maps, GPR scans, or visual imagery) in a format compatible with your asset integrity software, and annotated photos or video of any flagged areas.
Frequently asked questions
Does a climbing robot replace the need for scaffolding entirely?
Not for every task. It replaces the need for access equipment for inspection and survey work. If the job requires physical repair, welding, or coating work on the structure, scaffolding or rope access may still be needed for the repair crew.
How much does industrial scaffolding typically cost?
General market data puts basic frame scaffolding at roughly $40–$90 per day per section, with supervision and assembly around $75–$150 per hour — these are general ranges, not HausBots pricing, and vary significantly by site and scaffolding type.
Is rope access safer than scaffolding?
Both are established, regulated access methods with their own safety management systems (e.g. IRATA for rope access). Neither eliminates the fundamental fact that a person is working at height on the asset, which is the core risk robotic inspection removes for the inspection task itself.
How quickly can a robotic inspection be arranged compared to scaffolding?
Scaffolding for a large industrial job commonly takes at least ten business days from planning to installation. A robotic crawler, once scoped and booked, is typically deployed same-day on site with no erected access equipment.
Can a robot reach everywhere a rope access technician can?
Not always. Extremely complex or obstructed geometries may still favour a trained rope access technician. The right approach is usually to use robotic surveys for the majority of accessible surface area and reserve rope access for the specific spots a crawler can’t reach.
Does using a robot avoid the need for permits entirely?
No, site access, safety, and deployment permissions still apply. What changes is that a confined-space entry permit or working-at-height permit for a person is typically not needed for the inspection task itself.
Is a combination of methods common?
Yes. Many sites use robotic crawlers for recurring external survey work and reserve scaffolding or rope access for repair, maintenance, or the specific geometries a crawler can’t reach.
What's the fastest way to get an accurate cost comparison for my specific site?
Book a demo, HausBots will scope your specific asset, surface, and access requirements, which is the only reliable way to compare actual costs given how much they vary by site.
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