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NDT Testing

Balmore Wind Services Ltd is now pleased to offer their non-destructive inspection services to both new and existing clients.

Our experienced technicians are qualified to the British Institute of Non-Destructive Testing PCN scheme. The following services can now be provided upon enquiry:

ULTRASONIC INSPECTION

Ultrasonic inspection is predominantly used for wall thickness measurement and weld inspection. The technique is based on the propagation of ultrasonic energy in the object or material under test. These techniques are normally applied to the structures in order to detect corrosion, erosion, internal defects such as laminations or inclusions. They are also applied to welds to detect fabrication defects such as lack of fusion and when in-service to detect weld root erosion and fatigue cracks. These techniques rely on favourable orientation of the imperfections to be noted relative to the direction of the applied ultrasound. The geometry of the imperfection and component under test is also a main consideration.

testing for turbines

the importance of NDT Testing for wind turbines

EDDY CURRENT INSPECTION

Eddy current testing uses the principle of electromagnetic induction to detect flaws in conductive materials. An excitation coil carrying current is placed in proximity to the component to be inspected. The coil generates a changing magnetic field using an alternating current, which interacts with the component generating eddy currents. Eddy current inspection can be used to detect surface breaking flaws through non-conductive coatings which can save coating removal costs. Eddy currents can also be useful for the sorting of materials due to each materials conductivity. The inspection is efficient and can provide instant feedback.

MAGNETIC PARTICLE INSPECTION

Magnetic particle inspection is used for the detection of surface and near-surface flaws in ferromagnetic materials and is primarily used for crack detection. The specimen is magnetised either locally or overall, and if the material is sound the magnetic flux is predominantly inside the material. If, however, there is a surface-breaking flaw, the magnetic field is distorted, causing local magnetic flux leakage around the flaw. This leakage flux is displayed by covering the surface with very fine iron particles applied either dry or suspended in a liquid. The particles accumulate at the regions of flux leakage, producing a build-up which can be seen visually even when the crack opening is very narrow. Thus, a crack is indicated as a line of iron powder particles on the surface.

NDT Testing for wind turbines

LIQUID PENETRANT INSPECTION

The principle of liquid penetrant testing is that the liquid penetrant is drawn into the surface-breaking crack by capillary action and excess surface penetrant is then removed; a developer (typically a dry powder) is then applied to the surface, to draw out the penetrant in the crack and produce a surface indication. Cracks as narrow as 150 nanometres can be detected. The indications produced are much broader than the actual flaw and are therefore more easily visible.
Liquid penetrant inspection is typically used on non-ferromagnetic materials such as stainless steel.

VISUAL INSPECTION

Visual inspection, with or without optical aids, is the original method of NDT. Many defects are surface-breaking and can be detected by careful direct visual inspection. Optical aids include low-power magnifiers, microscopes, telescopes and specialised devices such as borescopes, endoscopes and other fibre-optic devices for the inspection of restricted access areas.

Balmore also offer UAV Inspection Services

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