Penetration Tests PT

PT testing is one of the oldest surface testing methods belonging to the non-destructive testing group. Penetration testing (PT, DPI) makes it possible to assess the surface quality of welds, as it is the weakest element in welded joints. Above all, discontinuities resulting from an incorrectly performed welding process, such as inclusions, cracks, etc., appear in welds. This technique is used to test both metallic and non-metallic materials, which can have ferro-, para- and diamagnetic properties. The wide applicability of this technique allows penetrant testing (PT) to be used to test metals and their alloys, ceramics, polymeric materials and glass.

PT testing – non-destructive penetrant testing

PT testing uses three reagents, i.e. a coloured or fluorescent penetrant, a remover and a developer. This method takes advantage of the phenomenon of movement of the liquid (waxiness phenomenon) based on the penetration of the coloured penetrant deep into the defects and crevices of the material under test. After a predetermined period of time, excess penetrant is removed using a remover and cleaning cloth. The final stage of PT testing involves the use of an auxiliary agent – a developer – which, based on the principle of contrast, allows leaky areas/defects/defects to beobtained/visualised.

In PT testing, it is very important to select the reagents in such a way that they do not have a detrimental effect on the material being tested and can effectively detect ‘defects’ in welded joints.

What can be tested by PT penetrant testing?

The PT penetrant method can detect surface defects/damage on all kinds of materials and products. The most common of these include:

• cracks;
• delaminations
• abnormal porosity;
• collapses;
• corrosion pitting;
• blisters and others.

Penetration testing (PT, DPI) is one of the most versatile NDT methods. Very often PT penetrant testing is used to test non-magnetic materials, i.e.: austenitic steels, heat-resistant and refractory alloys, metals and light alloys and copper, titanium and zirconium alloys.

If you have any doubts about whether PT testing can be carried out on a non-standard material, please contact Technic-Control Nondestructive Testing Laboratory’s customer service. Our consultants will be happy to assist you with any questions and/or concerns you may have.

Key features of penetration testing

Some of the most important advantages of penetrant testing include:

• the ability to perform tests on a variety of materials and products regardless of the size and shape of the material being tested;
• ease of application in both laboratory and field conditions;
• high detection of discrepancies as small as 0.001 mm;
• low testing costs;
• short testing time.

Disadvantages of non-destructive penetrant testing

• Detectability of surface discontinuities only;
• surface preparation of tested materials and its cleaning after testing;
• ageing of preparations used for testing;
• need for good ventilation in confined spaces.

How to carry out non-destructive penetrant testing?

Penetration testing is carried out in accordance with the PN-EN ISO 3452-1 standard, which is followed by the specialists at Technic-Control Nondestructive Testing Laboratory. As a result, the quality of testing and conclusions leave no doubt.

Prior to PT penetrant testing, the surface of welded joints is visually assessed, during which some defects/damage to the material under test can be seen. If such defects are not visible, penetrant testing can proceed. Non-destructive PT testing should begin with proper preparation of the surface to be tested, from which any contamination in the form of grease, dust, rust and also moisture must be removed.

A penetrating agent, which is a preparation with red dye or fluorescent additives, is applied to the thus prepared surface. The red dye is visible to the naked eye, while for fluorescent paints we use special UV lamps. This allows us to accurately locate where there is any discrepancy on the welded joint.

When the penetrant is applied, clear band lines and spots are observed. These mark the areas of absorption of the preparation. The next step is to clean the surface and apply the developer, which absorbs the liquid and clearly indicates the areas where discrepancies have formed. This is the final stage of penetrant testing, telling us about the quality of welded joints.

PT penetrant testing at Technic-Control Non-Destructive Testing Laboratory

When you need penetrant testing of welded joints, take advantage of the knowledge as well as the experience of Technic-Control Nondestructive Testing Laboratory. Why should you trust us? First of all, we have the experience gained during many years of work on large industrial facilities. We carry out PT tests at plants in the energy, mining, processing and transport industries. We carry out quality control on pipelines working with pressurised gases, high temperatures and aggressive substances. We also carry out non-destructive penetrant testing on tanks and in sensitive areas on ships and vessels.

In addition to our experience, our highly qualified testing personnel speak for us. All employees are non-destructive testing inspectors. They are certified in accordance with the EN ISO 9712 standard and are at least Level 2 specialists, and are supervised by Level 3 specialists. We carry out all work on professional equipment. Thanks to our qualifications and professional equipment, we can confirm the test results with appropriate certificates.

We can carry out penetrant testing anywhere. We cooperate with the largest contractors and caretakers of large strategic plants. We also provide services for smaller companies, subcontractors and craftsmen. Our surveys can be cyclical or one-off. We are able to travel to the location of your choice and at the most convenient time.

Would you like to commission a PT survey but are in doubt? Call the Technic-Control Non-Destructive Testing Laboratory customer service office today and our staff will provide you with all the details, arrange a test date, and quote for the service. You will also get advice on any other tests or services you need.