Test procedures

Non-destructive testing procedures

About the radiographic examination

Radiographic material testing is a commonly used non-destructive material testing method according to standard specifications.

The innovative tool of Control Labor is the DDA (Digital Detector Array), which is the only one we use in Hungary for non-destructive material testing. The use of this test is best recommended when we have large quantities of products and need to be inspected quickly and there is not yet a system in place at the test site.

About the procedure

Radiographic examination reveals various volumetric defects inside the test piece, volumetric continuity defects and allows the inspection of electromechanical products without disassembly.

A truly reliable, fail-safe, and mobile materials testing method.

Advantages and disadvantages of Digital Detector Array

The advantage of DDA is that it is a mobile device and imaging is performed simultaneously with the acquisition, allowing immediate evaluation. When used, a relatively small area needs to be fenced off, beyond 3.5 metres behind the source it is safe to work. In addition, it requires much less preparation time than any other technology, taking just 3 minutes to take an image with packing.

The only disadvantage is that it is an X-ray system, so it can only be operated by qualified personnel - before you ask if you can take it for the afternoon...;)

About ultrasonic materials testing

Ultrasonic testing (UT) is one of the most commonly used non-destructive testing methods. It detects in-plane and (sometimes) volumetric continuity defects in the components under test.

A technique used primarily for testing welds and materials. It is mainly used for testing steel (ferrites and austenites), aluminium, copper, but is also excellent for testing composites and other materials.

About the procedure

Ultrasonic materials testing is used to determine defects in homogeneous materials. Ultrasonic materials testing is based on the principle that ultrasound introduced into a sample propagates uniformly through the sample, but when it reaches a defect, or contamination, part of it is reflected. The defect site is an acoustic interface, and the sound waves move across it in different ways: they pass through or are reflected.

Advantages and disadvantages of UT

The advantage is that it is non-radiative at the time of testing, wall thickness does not matter, which makes it easier and more widely used, and does not require much test preparation.

It has the disadvantage that it does not produce a record in the traditional sense, but a sine curve is drawn when it is examined, which requires an expert eye to interpret.

About magnetic particle inspection

Magnetic materials testing is a popular non-destructive materials testing technique. It is used to detect continuity defects on or near the surface of ferromagnetic metals that are invisible to the naked eye or barely detectable.

It is commonly used to detect surface defects in welds and castings.

About the procedure

Metallic particles scattered on the surface to be tested and assembled by the magnetic field can be used to detect cracks and discontinuities in the material. The scattered magnetic field, which represents the surface discontinuity, can be detected by means of fine iron powder precipitated in petroleum. The condensed iron powder indicates the exact location and shape of the defect.

Advantages and disadvantages of MT

It has the advantage of being a relatively quick test, which can reliably detect surface defects in large quantities. It is not temperature-sensitive, and there are no problems with low or high temperature parts.

The disadvantage is that it can only be used on ferritic materials and defects deeper than 2mm can only be detected under special conditions.

About the liquid penetrant test

Liquid penetrant testing is a method used to detect continuity defects on the surface of a material, most commonly used to detect cracks, overlaps, lack of fusion and porosity.

In addition to metals, it can be used on all surfaces that are not too porous, for testing plastics and ceramics.

About the procedure

Under the right conditions, liquids with good wetting properties are able to penetrate narrow gaps due to the capillary effect and then seep back to the surface.

Taking advantage of this, after proper surface preparation, the penetrant is applied to the test surface, the penetration time (temperature dependent) is waited, excess penetrant is removed from the surface, the developer is applied, and during the development time, the surface is observed for any reabsorption that may indicate a defect.

Advantages and disadvantages of PT

The test method has the advantage that it is not only applicable to ferritic materials.

Disadvantage is that it is a slower process, you have to wait until the liquid penetrates the material, and then the developing fluid also has a drying time. Another disadvantage is that it is temperature-sensitive process.

About the visual inspection

The visual inspection is rarely a stand-alone test, typically part of a complex package of tests.

For non-destructive testing procedures, visual inspection is usually the first step, followed by MT or PT to detect surface defects, and finally RT and UT to detect defects inside the material.

About the procedure

Used as part of a complex investigation, it requires a high level of expertise and experience.

Its primary purpose is to detect discontinuities in structural elements and components, especially major discontinuities and material losses, and to determine geometric anomalies and also to detect traces of corrosion.