Eddy Current Testing for Cranes: Uses and Limitations

An inspector needs a defined question: is there a suspected surface crack near a connection, has a previous indication changed, or is a particular area being examined during a planned inspection? Asking whether the entire crane can be 'eddy current tested' leaves the relevant surfaces, coverage and acceptance criteria unresolved.

The method uses an electromagnetic field to induce currents in conductive material. Discontinuities and changes in material or geometry affect the response. A trained technician interprets that response using a suitable procedure and reference standards; a signal is not automatically a crack.

For a component-specific plan, the inspection and testing service can consider eddy current testing alongside other methods rather than prescribing it for every crane.

Eddy current testing may be considered for accessible conductive parts where surface or near-surface cracking is the concern. Suitability depends on material, component shape, surface condition and the expected defect orientation. It is not a volumetric survey of every internal region.

For example, an engineer investigating a recurring indication around a connection may seek a targeted examination supported by earlier reports and a location drawing. The technician must first establish whether the geometry permits reliable coverage and whether another method would answer the question more clearly.

Some techniques can examine through certain non-conductive coatings, but this is not permission to assume any painted surface is suitable. Coating thickness, probe lift-off, corrosion, roughness and changing curvature can affect sensitivity. Edges, holes and nearby features can also produce responses unrelated to damage.

Material conductivity and magnetic properties matter. Results on one alloy or component cannot simply be transferred to another. If access prevents adequate probe movement, the report should describe the limitation rather than imply complete coverage.

Ask the provider what access and surface preparation are required before removing coatings or dismantling parts. Uncontrolled grinding can remove evidence or damage a highly stressed surface. Site isolation and access arrangements belong in the agreed work plan.

• Provide crane and component identification, drawings and material grades where known.
• Identify the suspected area with photographs and a repeatable location reference.
• Supply previous NDT reports, repairs and relevant incident history.
• Describe paint, plating, corrosion, access restrictions and available shutdown time.
• Confirm who will review indications and determine the next engineering action.

A useful report identifies the method, procedure, areas examined, reference system, findings and limitations. An absence of reportable indications means no such indications were identified within that examination's capability and coverage; it does not prove unlimited remaining life or certify the whole crane.

Ask whether a finding needs confirmation, complementary NDT or engineering review. Keep the report with the asset record so future inspections can compare the same location. Decisions about repair or continued service should address the equipment-specific criteria and the wider inspection evidence.