Normally, experts who use NDT testing equipment to perform distinct non destructive tests perform five types of NDT testing. These NDT tests are common for tube and pipe weld inspection and every test has its unique advantage and disadvantage. You need to know about these tests completely to avail all benefits and avoid suitability issues.
Non Destructive Testing or NDT testing includes processes to test various materials for surface or internal flaws or metallurgical condition without involving in any way with material integrity or its suitability for service.
Five NDT techniques are-
- Magnetic particle crack detection
- Dye penetration testing
- Ultrasonic flaw detection
- Eddy current electromagnetic testing
Radiography – This type of testing is helpful in detecting internal defects in ferrous and non-ferrous metals. X-rays developed electrically, and gamma rays released from radioactive isotopes penetrate radiation that is soaked by the material (passed through). Absorption rate depends on the thickness of the material, greater the thickness means greater the absorption of rays.
Tools used by experts- There are many radiographic and photographic accessories needed for the test, including radiation monitors, film makers, darkroom equipment and image quality indicators. Radiographic film and processing chemicals are also needed in the list.
Benefits of radiography –
- Information is presented pictorially
- There is a permanent record
- Ideal for thin sections and suit any material
- Each film is sensitive
- It is not suitable for surface defects and for automation
- It cannot cope with thick sections
- It doesn’t indicate the depth of defect below the surface
Advantages of Magnetic particle inspection –
- Easy to operate and apply
- It is quantitative testing
- Special camera captures the defect indication image for display
- This method can be automated
Disadvantages of Magnetic particle inspection-
- It is limited to ferromagnetic materials, surface and near-surface flaws.
- Magnetic particle inspection is not fail-safe
- Guaranteed results are not expected
Advantages of dye penetrant testing
- It is simple to perform
- It is easy way to detect surface breaking cracks in non ferrous metals
- It is suitable for automatic testing
Disadvantages of dye penetrant testing
- It is limited to surface-breaking defects
- It is less sensitive
- It uses considerable amount of consumables
Advantages of UT flaw detection
- It is used to test thickness and length up to 30 feet.
- You can determine defect position , size and type
- This is portable type testing
- No need of consumables
Disadvantages of UT flaw detection
- Test indications need interpretation
- Skills are needed to perform test and avail maximum information
- Thinner sections can be difficult to test
Advantages of Eddy current testing
- It is suitable for automation
- It helps in determining defects related to composition, hardness, permeability and conductivity
- No need of consumables
- It is flexible
Disadvantages of Eddy Current testing
- It is limited to surface breaking conditions and slightly subsurface flaws
For more details on NDT testing equipment and methods, you can contact EIE professionals.