NDT – Non-Destructive Testing
July 10, 2025 2025-09-22 11:58NDT – Tahribatsız Muayene
NDT – Non-Destructive Testing
As Biltek Quality Engineering Services, the Non-Destructive Testing (NDT) services we offer ensure the detection of surface and structural defects across a wide range of areas, from basic materials to final products, assemblies, and industrial equipment. This enables the prevention of risks and costs that may arise from potential material failures in advance, creating safe and sustainable processes.
Our services are conducted in full compliance with nationally and internationally recognized standards, contributing to businesses' operational efficiency, product reliability, and sustainable quality management.
Radiographic Examination
Radiographic inspection, one of the volumetric methods of non-destructive testing, is used to detect internal defects in welded joints, castings, forgings, and plastic products using naturally occurring radioactive isotopes (Ir-192, Se-75, Co-60) or X-rays.
The beam of radiation emitted from the radiation source penetrates the test piece and, after weakening at varying rates, strikes the film placed behind the test piece. Linear X-rays and gamma rays, due to the differing densities of the material and the discontinuities within it, cause the projections of these discontinuities to be clearly visible on the film.
Radiographic testing provides highly accurate results, and these results can be permanently recorded. It can be applied to all materials. The accuracy and reliability of the radiographic examination performed can be understood through the radiographs.
As a disadvantage, it contains radiation and can be harmful to health if the necessary precautions are not taken. Exposing, developing, and viewing the film is a relatively slow technique. Furthermore, it is not possible to obtain information about the depth of the defect detected beneath the surface.
EN ISO 5579 – Non-destructive testing – General principles for radiographic examination of metallic materials using film and X-rays or gamma rays
EN ISO 17636 – 1 – Non-destructive testing of welds – Radiographic testing – Part 1: Film-based X-ray and gamma-ray techniques
EN ISO 17636-2 – Non-destructive testing of welds – Radiographic testing – Part 1: X-ray and gamma-ray techniques using digital detectors
EN ISO 10675 – 1 – Non-destructive testing of welds – Acceptance levels for radiographic testing – Part 1: Steel, nickel, titanium and their alloys
EN 12681 – Casting – Radiographic inspection
EN ISO 10893-6 – Non-destructive testing of steel pipes – Part 6: Radiographic examination of welded joints in welded steel pipes for the detection of defects
EN ISO 10893-7 – Non-destructive testing of steel pipes – Part 7: Digital radiographic examination of welded steel pipes for the detection of defects
TS EN ISO 10042 – Welding – Arc welded joints in aluminum and alloys – Quality levels for irregularities
ISO 11971 – Surface quality of steel castings AD 2000-MERKBLATT HP 5/3: Manufacture and testing of joints – Non-destructive testing of welded joints. Visual inspection
ASME Boiler and Pressure Vessel Code – Section V: Nondestructive Examination
ASME B31.1 Power Piping Changes
ASME B31.3 Process Piping Code Changes
ASME B31.8 Gas Transmission and Distribution Piping Systems
API 5L Specification for Line Pipe
API 653 Aboveground Storage Tank Inspector
API 1104 Welding of Pipelines and Related Facilities
Ultrasonic Inspection
Ultrasonic Testing is a volumetric non-destructive testing (NDT) method. The working principle of Ultrasonic Testing is based on the echo generated by the reverse piezoelectric effect in the probe, which produces short-pulse sound waves using a piezoelectric crystal, and the return of this echo from the back wall of the material to the device. The echo returning from a discontinuity in the material appears as a peak on the device screen.
The greatest advantage of ultrasonic testing is that it reveals the location of discontinuities within the material. When ultrasonic testing is performed on welded metals, the location of discontinuities at the root of the weld and in the heat-affected zone can be determined. Based on the working principle of the ultrasonic test mentioned, the thicknesses of materials are also measured. It can also be used to detect volumetric defects and crack-type surface defects in metallic or non-metallic materials.
The ultrasonic test is portable and provides instant results. Its disadvantage is that it can only be applied to materials thicker than 8mm. Furthermore, it is difficult to apply the ultrasonic method to austenitic (coarse-grained) materials.
Some Standards Used in Ultrasonic Testing:
EN ISO 16810 – Non-destructive testing – Ultrasonic testing: General rules
EN ISO 11666 – Non-destructive testing of materials – Ultrasonic testing – Acceptance levels
EN ISO 22825 – Non-destructive testing of welds – Ultrasonic testing – Inspection of welds in austenitic steels and nickel-based alloys
EN ISO 12680 – 1 – Castings – Ultrasonic testing – Part 1: General purpose steel castings
EN ISO 12680 – 2 – Casting – Ultrasonic testing – Part 2: Steel castings subject to high stresses
EN ISO 12680 – 3 – Casting – Ultrasonic testing – Part 3: Cast iron with spheroidal graphite
EN 10228 – 3 – Non-destructive testing of steel forgings – Part 3: Ultrasonic testing of ferritic or martensitic steel forgings.
EN 10228 – 4 – Non-destructive testing of steel forgings – Part 4: Ultrasonic testing of austenitic and austenitic-ferritic stainless steel forgings
EN ISO 10893-8 – Non-destructive testing of steel tubes – Part 8: Automatic ultrasonic testing of seamless and welded tubes for the detection of planar defects
EN ISO 10893-9 – Non-destructive testing of steel tubes – Part 9: Automatic ultrasonic testing of steel strips/plates used in the manufacture of welded tubes for the detection of planar defects
EN ISO 10893-10 – Non-destructive testing of steel pipes – Part 10: Automatic full-circumference ultrasonic testing of seamless and welded steel pipes (excluding submerged arc welded pipes) for the detection of longitudinal and/or transverse defects
EN ISO 10893-11 – Non-destructive testing of steel pipes – Part 11: Automatic ultrasonic testing of welded steel pipes for the detection of transverse and/or longitudinal defects
TS EN ISO 10042 – Welding – Arc welded joints in aluminum and alloys – Quality levels for irregularities
EN 10308 – Non-destructive testing – Ultrasonic testing of steel bars
ISO 11971 – Surface quality of steel castings AD 2000-MERKBLATT HP 5/3: Manufacture and testing of joints – Non-destructive testing of welded joints. Visual inspection
ASME Boiler and Pressure Vessel Code – Section V: Nondestructive Examination
ASME B31.1 Power Piping Changes
ASME B31.3 Process Piping Code Changes
ASME B31.8 Gas Transmission and Distribution Piping Systems
API 5L Specification for Line Pipe
API 653 Aboveground Storage Tank Inspector
API 1104 Welding of Pipelines and Related Facilities
Magnetic Particle Test
Magnetic particle testing (MT) is a non-destructive testing (NDT) method used to inspect the surface integrity of ferromagnetic materials. The basic principle involves magnetizing the material to be tested. The magnetization process is achieved by passing an electric current or magnetic flux through the part. This can be done using a hand-held yoke, an electro-coil, a central conductor, or a moving electrode. Since the test materials are ferromagnetic, they contribute to the passage of the magnetic flux.
Surface and near-surface defects and voids within a magnetic field impede and deflect magnetic field lines. This results in concentrated leakage flux over the defect. When a liquid containing small magnetic particles is applied, these particles accumulate around the defects, making them visible to the naked eye. To make the defects more clearly visible, a white contrast agent is applied to the material before testing. For high sensitivity, a fluorescent liquid is used under ultraviolet (UV) light. This requires a dark testing environment.
Key advantages of magnetic particle testing:
- Inspection of large surfaces can be performed quickly, with immediate results.
- Defects can be seen directly on the surface along with their dimensions.
- The equipment is relatively inexpensive.
- It is portable. In the absence of electricity, a battery-operated neck brace can be used.
- There is no critical surface preparation and cleaning.
Apart from these advantages, its application is limited to ferromagnetic materials only. It does not work on surfaces coated with paint or similar materials. It does not produce reliable results on rough surfaces.
Some Standards Used in Magnetic Particle Testing:
EN ISO 9934-1 2016 – Non-destructive testing – Magnetic particle testing – Part 1: General rules
EN 1330-7 – Non-Destructive Testing – Terminology – Part 7: Terms used in magnetic particle testing
EN ISO 17638 – Non-Destructive Testing of Welds – Magnetic Particle Testing
EN ISO 23278 – Non-Destructive Testing of Welds – Magnetic particle testing – Acceptance levels
EN 1369 – Castings – Magnetic particle inspection
EN 10228-1 Non-destructive testing of steel forgings – Part 1: Magnetic particle testing
EN ISO 10893-5 – Non-destructive testing of steel tubes – Part 5: Magnetic particle testing of seamless and welded ferromagnetic steel tubes for the detection of surface defects
ISO 11971 – Surface quality of steel castings AD 2000-MERKBLATT HP 5/3: Manufacture and testing of joints – Non-destructive testing of welded joints. Visual inspection
ASME Boiler and Pressure Vessel Code – Section V: Nondestructive Examination
ASME B31.1 Power Piping Changes
ASME B31.3 Process Piping Code Changes
ASME B31.8 Gas Transmission and Distribution Piping Systems
API 5L Specification for Line Pipe
API 653 Aboveground Storage Tank Inspector
API 1104 Welding of Pipelines and Related Facilities
Liquid Penetrant Test
Liquid Penetrant Testing (PT) is used to detect surface cracks. Penetrant testing can be applied to a wide variety of materials: metallic and non-metallic, magnetic and non-magnetic, and conductive and non-conductive. Examples of metallic materials that can be tested include aluminum, magnesium, titanium, copper, brass, bronze, and many alloys; examples of non-metallic materials include ceramics, plastics, and glass. This method uses the capillary effect principle. A low-viscosity liquid dye is applied to the test piece. Due to its low viscosity, it is well drawn into surface discontinuities. After sufficient penetration time, excess liquid is rinsed off. After drying, a chalk-like developer is applied. The developer draws out the penetrated dye. The defect becomes visible and can be interpreted by the operator. For high sensitivity, fluorescent penetrant is used under ultraviolet (UV) light. This requires a dark testing environment.
There are certain properties that the penetrant fluids used in every liquid penetrant inspection must possess. These are:
- It spreads easily over the entire surface of the test piece.
- It enters discontinuity due to capillary action.
- During intermediate cleaning, it is easily removed from the part surface but remains within the discontinuity.
- It remains liquid during examination and is easily reabsorbed.
- Its fluorescent properties make it easy to spot and provide high visibility.
- It does not deform the part.
- There is no harm to the operator.
In addition to these, liquid penetrant testing generally stands out as an economical, portable, and fast method. It is highly sensitive to adjacent discontinuities, and all discontinuities on the surface can be detected in a single operation.
Some Standards Used in Liquid Penetrant Testing:
TS EN ISO 3452-1 – Non-destructive testing – Penetrant testing – Part 1: General rules
EN ISO 23277 2015 – Non-destructive testing of welds – Penetrant testing of welds – Acceptance levels
TS EN 1371-1 2012 – Castings – Liquid penetrant inspection – Part 1: Sand, non-pressure and low-pressure molds
TS EN 1371-2 2015 – Castings – Liquid penetrant testing – Part 2: Precision castings
EN ISO 10228-2 – Çelik dövmelerin tahribatsız muayenesi – Bölüm 2: Penetrant muayenesi
EN ISO 10893-84 – Çelik boruların tahribatsız muayenesi – Bölüm 4: Yüzey kusurlarının tespiti için dikişsiz ve kaynaklı çelik boruların sıvı penetrant muayenesi
TS EN ISO 10042 – Welding – Arc welded joints in aluminum and alloys – Quality levels for irregularities
ISO 11971 – Surface quality of steel castings AD 2000-MERKBLATT HP 5/3: Manufacture and testing of joints – Non-destructive testing of welded joints. Visual inspection
ASME Boiler and Pressure Vessel Code – Section V: Nondestructive Examination
ASME B31.1 Power Piping Changes
ASME B31.3 Process Piping Code Changes
ASME B31.8 Gas Transmission and Distribution Piping Systems
API 5L Specification for Line Pipe
API 653 Aboveground Storage Tank Inspector
API 1104 Welding of Pipelines and Related Facilities
Visual Inspection
Visual testing (VT) involves visually inspecting the surface of the test piece to assess the presence of surface discontinuities such as corrosion, misalignment of parts, physical damage, and cracks. Visual tests can be performed by looking directly at the test piece or by using optical instruments such as magnifying glasses, mirrors, borescopes, and computer-aided imaging systems. Visual inspection can be applied to examine castings, forgings, machined parts, and welds, and is used in all branches of industry.
During examinations, auxiliary tools such as endoscopes, mirrors, and borescopes may be used as necessary, depending on the shape and structure of the material and the accessibility of the area to be examined.
Visual inspection may seem like a simple method, but it is an important inspection method. It must be performed before other non-destructive inspection methods are applied.
If visual inspection is performed before welding, during welding, and after welding, discontinuities can be detected without the need to apply other non-destructive testing methods, thereby preventing excessive costs and saving time.
Some Standards Used in Visual Testing:
EN 13018 – Non-destructive testing – Visual inspection – General rules
EN 1330-10 Non-destructive testing – Terminology – Part 10: Terms used in visual inspection
EN ISO 17637 – Non-destructive testing of fusion welds – Visual inspection of fusion welded joints
EN ISO 5817 – Welding – Fusion welding of steel, nickel, titanium and their alloys (excluding spot welding) – Quality levels for defects
TS EN ISO 10042 – Welding – Arc welded joints in aluminum and alloys – Quality levels for irregularities
ISO 11971 – Visual inspection for surface quality of steel castings
ISO 11971 – Surface quality of steel castings AD 2000-MERKBLATT HP 5/3: Manufacture and testing of joints – Non-destructive testing of welded joints. Visual inspection
ASME Boiler and Pressure Vessel Code – Section V: Nondestructive Examination
ASME B31.1 Power Piping Changes
ASME B31.3 Process Piping Code Changes
ASME B31.8 Gas Transmission and Distribution Piping Systems
API 5L Specification for Line Pipe
API 653 Aboveground Storage Tank Inspector
API 1104 Welding of Pipelines and Related Facilities
Visual testing (VT) involves visually inspecting the surface of the test piece to assess the presence of surface discontinuities such as corrosion, misalignment of parts, physical damage, and cracks. Visual tests can be performed by looking directly at the test piece or by using optical instruments such as magnifying glasses, mirrors, borescopes, and computer-aided imaging systems. Visual inspection can be applied to examine castings, forgings, machined parts, and welds, and is used in all branches of industry.
During examinations, auxiliary tools such as endoscopes, mirrors, and borescopes may be used as necessary, depending on the shape and structure of the material and the accessibility of the area to be examined.
Visual inspection may seem like a simple method, but it is an important inspection method. It must be performed before other non-destructive inspection methods are applied.
If visual inspection is performed before welding, during welding, and after welding, discontinuities can be detected without the need to apply other non-destructive testing methods, thereby preventing excessive costs and saving time.
