Corrosion test

Corrosion test refers to the systematic examination of metals and metallic components for corrosion damage, rate, and causes. In the context of concrete demolition, rock excavation, gutting works, and cutting operations, it provides robust decision-making bases: for the structural analysis of corroded reinforcement in concrete, for selecting and safely operating concrete demolition shears, hydraulic rock and concrete splitters, as well as for condition-based maintenance of hydraulic power units, steel shears, tank cutters, combination shears, multi cutters, and stone splitting cylinders. The findings reduce unplanned downtime, enable evidence-based risk assessment, and support compliance with project and site-specific safety requirements.

Definition: What is meant by a corrosion test?

Corrosion test encompasses methods and procedures for assessing materials and components regarding their susceptibility to different types of corrosion. The goal is condition assessment, root cause analysis, and forecast of further material degradation. In practice, visual, mechanical, electrochemical, and non-destructive tests are combined to detect, for example, pitting, crevice corrosion, galvanic couples, underfilm corrosion, stress corrosion cracking, as well as corrosion-related cross-section losses and crack networks. In concrete structures, this often concerns reinforcement and built-in components; for equipment and tools, the focus is on load-bearing structures, hydraulic components, sealing and connection elements.

Typical deliverables of a professionally planned corrosion test include: condition classes with acceptance criteria, rate estimates (e.g., mm/a), location-referenced maps of active areas, and action plans for repair or continued operation.

Relevance in concrete demolition and special deconstruction

Corrosion dictates the approach in many projects: corroded reinforcement affects load transfer in concrete and thus the safe use of concrete demolition shears or similar tools in selective deconstruction. In humid, chloride-laden environments (for example, in parking structures, wastewater treatment plants, or tunnels) advanced reinforcement corrosion and spalling occur, influencing the choice of separation method and the opening sequence during gutting works and cutting. In rock excavation and tunneling, humid air, splash water, and dust impact steel components of rock and concrete splitters; regular corrosion tests ensure the functionality of cylinders, pins, grippers, cutting edges, and hydraulic connections.

Where combustible or hazardous residues are present in tanks and process equipment, corrosion-related wall thinning and leak paths must be identified early to define safe work envelopes for cold or hot cutting procedures and to prevent unforeseen load redistributions.

Typical test methods and measured variables

In practice, procedures are combined according to their suitability for the material, component, and environment. Key measured variables are corrosion potential, corrosion current density, coating thicknesses, remaining cross-section, surface roughness depth, crack indications, as well as environmental parameters such as pH value, chloride content, and moisture content. Where useful, mass loss of coupons and electrical resistance probes complement on-site data for trend analysis.

Visual and mechanical examinations

• Visual inspection with magnifiers/endoscopes to detect rust nests, underfilm corrosion, spalling, and crack indications.
• Mechanical thickness measurements, inspection grinds on replaceable wear parts (e.g., cutting edges, jaws), comparison with wear limits.
• Coating thickness measurement on steel components; adhesion testing (e.g., cross-cut) for protection systems.
• Replicas and high-resolution surface impressions at critical pivot points to document pit geometry and microcrack initiation.

Electrochemical methods on steel and reinforcement

• Corrosion potential measurement (for example, half-cell method) to localize active areas in concrete components.
• Linear polarization resistance to estimate the corrosion rate.
• Electrochemical impedance spectroscopy to assess coatings and passive layers.
• Supplementary resistivity measurement of concrete cover to evaluate the likelihood of macrocell formation and moisture pathways.

Non-destructive testing (NDT)

• Ultrasonic testing, eddy current, magnetic particle, and dye penetrant testing for crack and defect detection on steel components, scissor arms, shear blades, and adapter plates.
• Concrete-specific: potential mapping, concrete cover measurement, chloride analysis, and carbonation depth to evaluate reinforcement corrosion.
• Advanced UT (e.g., phased array) where geometry allows, to size subsurface flaws before they become operationally relevant.

Laboratory and environmental simulation tests

• Salt spray/salt fog tests and cyclic corrosion tests for comparative evaluation of protection systems.
• Condensation and humidity cycling tests for housings, couplings, and electrical components of hydraulic power packs.
• Gravimetric coupon exposure and immersion tests in representative media to quantify mass loss and pit density for material pairings.

Corrosion types and damage patterns in practice

Corrosion rarely occurs in isolation. Frequently, uniform material loss overlaps with pitting at edges, crevice corrosion in joints, as well as galvanic corrosion between dissimilar metals (e.g., stainless steel insert and unalloyed steel). Tanks that still contain combustible media may be thinned internally by media corrosion; wall thickness must be verified before using tank cutters. In concrete demolition shears, corrosion-assisted microcracks often appear at highly loaded pivot points, growing due to recurrent load cycles. Rock and concrete splitters are prone to corrosion under deposits at piston rods and lines when moisture and dust coincide.

In addition, hydrogen-assisted cracking can occur in high-strength fasteners and tool steels, while microbiologically influenced corrosion appears in wastewater and stagnant moisture. Underfilm corrosion beneath coatings is typically driven by chlorides and wet-dry cycling, advancing unnoticed until coating disbondment is visible.

Specific requirements for tools and components

The corrosion test is tailored to the function, material, and loading of the tools. Inspection intervals are pragmatically adapted to operating hours, media contact, and place of use. Acceptance criteria should be clearly defined, for example permissible pit depth at cutting edges, minimum remaining wall thickness at cylinders, or maximum allowable leakage and roughness at sealing surfaces.

Concrete demolition shears: focus areas of the inspection

• Bearings, pins, and bushings: dimensional accuracy, crack indications, corrosion burrs; check lubrication condition.
• Shear and breaking jaws: remaining cutting length, chipping, underfilm corrosion beneath wear protection plates.
• Hydraulics: inspect lines, couplings, and cylinder heads for rust, weeping points, contact corrosion, and underfilm paint corrosion.
• Fasteners: torque verification on critical bolted joints; assess thread corrosion and galling risk.

Rock and concrete splitters: hydraulics and cylinders

• Piston rods: surface condition, scoring, pitting; condition of sealing lips.
• Splitting wedges and springs: corrosion notches and dimensional accuracy, especially after contact with moist drill cuttings.
• Distributor blocks and power packs: condensate formation, brackets, protective caps; check electrical plug connections for corrosion.
• Hoses and quick couplings: red rust at sleeves, under-sleeve crevice corrosion, and protective sleeve integrity.

Other tools in deconstruction

• Steel shears and multi cutters: crack testing on shear blades, pitting at cutting edges, fastening bolts.
• Combination shears: transitions between material pairings; minimize galvanic couples.
• Tank cutters: wall thickness measurement and media-induced internal corrosion; atmospheric external corrosion under insulation.
• Adapters and mounting plates: fretting corrosion at interfaces and protection of machined surfaces during storage.

Influencing factors: environment, media, and operating profile

Corrosion progression strongly depends on climate and use. High humidity, chlorides (de-icing salt, marine proximity), sulfates, CO2-induced carbonation of concrete, temperature fluctuations, and abrasive dusts increase the risk. In tunneling, condensate and aerosols promote coating underfilm corrosion; in natural stone quarries, rain, mud, and UV radiation act. In special applications with chemical media, chemical resistance must also be considered.

• Electrical and stray currents near power rails and welding return paths can intensify local attack and crack growth.
• Microclimates inside enclosures and under insulation maintain high time-of-wetness, accelerating underfilm corrosion.
• Operating profile: short idle periods versus seasonal storage require adapted temporary protection and preservation plans.

Test planning, documentation, and condition assessment

A robust corrosion test follows a structured plan with clear inspection points, evaluation criteria, and documentation.

1. Define objectives: structural stability, functional safety, maintenance needs, remaining service life.
2. Select methods: a combination of visual, NDT, and electrochemical methods, adapted to the component and accessibility.
3. Measurement strategy: grid, reference points, repeatability; record environmental parameters.
4. Evaluation: classify into condition categories, define measures (continued operation, repair, replacement).
5. Documentation: photo records, measurement logs, test reports, and recommendations for inspection intervals.

• Traceability: unique component IDs, geo-referenced findings where meaningful, and consistent calibration records.
• Trending: compare successive campaigns, establish trigger thresholds for intervention, and visualize hotspot evolution.

Normative and technical foundations

There are recognized standards and guidelines for corrosion tests and corrosion protection, for example, rule sets on terminology, salt spray and cyclic tests, qualification of NDT personnel, concrete technology and repair, as well as coating systems for steel surfaces. The exact application varies depending on the project, component, and national regulations. Tests should always be expertly planned and executed.

In addition, technical specifications for cathodic protection, rebar corrosion assessment, and acceptance of protective coating systems provide benchmarks for method selection, execution quality, and documentation depth.

Relation to areas of application: practical examples

Concrete demolition and special deconstruction

Before separating load-bearing components, corrosion mapping of reinforcement provides indications of cross-section losses and potential unexpected load redistributions. This influences gripping and cutting strategies of concrete demolition shears as well as the sequence of cuts. If necessary, temporary supports and alternative separation methods are defined to maintain structural integrity during the process.

Gutting works and cutting

In existing buildings with moisture damage, reinforcement can be locally heavily corroded. NDT and potential measurements help identify critical zones. At cutting tools, bearings and hydraulics are checked in parallel for signs of corrosion to avoid failures during ongoing operations.

Rock excavation and tunneling

Humid, saline aerosols accelerate corrosion on exposed steel parts. Regular inspections on rock and concrete splitters, especially on piston rods, fastenings, and protective caps, stabilize operational safety.

Natural stone extraction

Mud and mineral dusts promote crevice corrosion in joints. Cleaning and visual inspection intervals should be adjusted accordingly; replaceable wear parts are evaluated against defined limits.

Special operations

For work on tanks and systems with chemical pre-exposure, internal media corrosion must be expected. Wall thicknesses must be verified before separation work, and potential ignition sources minimized; tests are performed cautiously and adapted to the media.

Prevention, maintenance, and inspection intervals

Corrosion can be significantly slowed by coordinated measures. The combination of suitable protection, proper application, and regular inspection is decisive.

• Surface protection: coatings, galvanic protection systems, suitable material pairings; treat edges and joints with particular care.
• Design protection: avoid water traps, provide run-off and drip edges, covers for exposure phases.
• Operation: cleaning after deployments in saline/muddy environments; drying, preservative lubrication at bearings.
• Hydraulics: media cleanliness, water content, filtration; use corrosion inhibitors as approved.
• Inspection intervals: stagger by operating hours and exposure; initially shorter, later extended or shortened based on condition.
• Storage and transport: dry, ventilated conditions, breathable covers, and periodic re-preservation for long idle periods.

Safety and responsibility

Corrosion test serves hazard prevention and health protection. Results flow into work and assembly instructions and support the selection of suitable tools, such as concrete demolition shears or rock and concrete splitters, for the specific component and environment. Legal requirements may vary by country and project; inspection and maintenance obligations must be observed carefully. Statements in this contribution are of a general nature and do not replace individual assessment.

For operations on tanks and enclosed systems, safe work systems with permits, gas measurements, and continuous monitoring are essential. Corrosion findings are to be reflected in risk assessments and method statements to ensure safe execution at all stages.