Comment choisir la meilleure technique CND pour un matériau et un défaut donnés ?

To choose the appropriate test method, the most important issue is to identify the mechanisms and the modes of damage. For example, the mode of damage may be cracks, but to identify it, ultrasonic point thickness measurement is used, which is not effective in practice. The ASME PCC-3 (Table C-1) is a good initial guide to match the effective inspection method to the damage mode and mechanism.

To choose the best Non-Destructive Testing (NDT) method: 1. Know the material type. 2. Understand the defect you're looking for. 3. Consider the part's shape and size. 4. Look at safety and cost. 5. Pick the method that gives clear results for your need.

Two very important factors are the consequences of an escape and the design margin. If the design has little safety margin and the consequences of an escape could be a catastrophic failure, then you are looking at at least 100% inspection using a technique with high reliability, like automated phased-array UT. If the design is very robust and you are just trying to minimise warranty claims then you can use more basic techniques, like sample inspection with handheld probes. So the answer is: talk to your design team.

It depends on the materials. But, Mostly UT is the best method for most of materials. It helps to detect both thickness of materials and defects. Two in one from one method. one of easiest method in NDT.

Refer to the standard reference of the testing you need to start with. Especially each NDT has its own specific requirement. For example, ASTM, ISO, etc., have their specific requirement and conditions for the materials and shapes specific to their test. Most people tend to ignore this and end up wasting the materials, or the test will become obsolete.

All materials have defects, but to understand those defects, you can identify them with your eyes (or other senses). First thing to do is to refer to the international standard, i.e., ASTM, ISO, etc. Then, use microscopes to identify the surface crack, etc. before starting the destructive test. Density profile and sound absorption test are other tests to find defects in the sample materials.

Another factor to consider is the ACCESSIBILITY and location of the Member Part/ defects, consider inspecting a 1km subsea pipeline buried 10m into the subsea, one will start to think of excavation of topsoil for all the length of the pipeline for better accuracy of results, not all NDT methods can work with this, However there is a new technology call the Non- Contact Magnetometric (NCM) Inspection that can do this without excavation, the tool needs to be attached to the ROV which in turn flies the path of the buried pipeline, data is stored memory or taken real time.

Identify the type, size, location, and orientation of the defect you are trying to detect or characterize. Consider whether the defect is surface-breaking or subsurface, and whether it is internal or external.

this is a little more complicated as it seems. as an inspector always ask for a clear policy for your work. and as a employer or contractor, the best way to figure out the best standard is based on the local rules. they've all conducted the requirements in codes of national regulations in the specific field.

Various non-destructive testing (NDT) methods demonstrate exceptional ability in detecting particular sorts of faults. Defects located at different depths necessitate the use of non-destructive testing (NDT) techniques with varying levels of penetration capability. Radiography possesses the capability to penetrate dense substances, making it appropriate for detecting faults that are located deep within an object. In contrast, ultrasonic testing provides exceptional resolution for flaws located close to the surface but may have difficulty detecting problems that are located at significant depths. The choice of NDT methodology depends on understanding the particular fault being addressed.

Another important metric not explicitly mentioned in this text is probability of detection (POD) for a given type and size of defect. Depending on the consequences of not finding a defect you can set what POD you find acceptable for a given defect. POD can be found experimentally, or perhaps from literature. POD will depend on the material and defect compared to the technique used, but also the skill and experience of the inspector. Also, don't forget about the operational context! POD in a well lit lab when the part is lying on a table is probably better than when the inspector is outside at night in the cold and rain, or when the inspector is crawling around inside a narrow structure.

All techniques have their limitations and capabilities, which is the reason why we need replication and multidisciplinary tests to support and justify each claim made. Cross-checking by using a destructive and other chemical test is a must to ensure the result is reliable. In addition, referring to international standards, i.e., ASTM, ISO helps to ensure the test is verified and reliable.

The capabilities of non-destructive testing (NDT) techniques include the ability to detect defects without causing damage to components, ensuring safety, cost savings, quality assurance, minimized downtime, extended lifespan of equipment, environmental protection, data-driven decision-making, preservation of historical artifacts, reduced material waste, real-time inspection, and improved reliability. However, NDT techniques also have limitations, such as the need for highly trained technicians, the requirement for specific equipment for different methods, and the inability to detect internal defects in certain materials without more advanced techniques like radiographic testing.

It would depend on the type of defect sought and what information you needed on their features. For example, if any defects might be open to the surface, visual inspection and dye penetrant testing could identify them. Other methods such as radiography or ultrasonic testing could quantify depths or locate internal defects, inclusions, etc.

Most mistakes made by the new researcher are that all the tests were done according to their own theory. Most of them are unable to relate to international standards, especially when writing journals or other publications. International standards and codes are important to ensure that it is recognized and verified and done in the proper way accepted by industry with justification that the product that was tested can be used in daily life. The reason why rejection occurs during submission of a report/journal is due to negligence of acknowledgement of these standards and codes.

Here is the list of the most used standards: . The American Society for Nondestructive Testing (ASNT) . ASTM International . American Society of Mechanical Engineers (ASME) . American Petroleum Institute (API) . American Welding Society (AWS) . National Board of Boiler and Pressure Vessel Inspectors (NBBI) . International Organization for Standardization (ISO) . European Committee for Standardization (CEN)

Each NDT data analysis and interpretation usually were back up with cross-reference justification. It can be divided into two: one is in the same cross-NDT test, and the other one is from a destructive test (includes chemical, mechanical, etc.). This cross-multidisplinary is a must to ensure that the data in NDT is reliable as well according to the standard. This justifies and makes your products reliable and trustworthy. Always prove something you claim with evident and justification.

Consult with seasoned NDT professionals or consultants who can offer valuable insights derived from their expertise and extensive experience in the field.

Seek advice from experienced NDT professionals or consultants who can provide insights based on their expertise and experience.

Choosing the best NDT technique also depends on; 1. What you want to measure, If it's metal thickness, painting coat thickness, etc the approaches are different.  2. Location of defect. If the area can be visible on both sides, the X-rays will be suitable; otherwise a die penetrant test or vacuum test will be suitable. Inline pipe inspection uses ultrasonic intelligent pipeline integrity gauges (PIGs) instead of normal ultrasonic tools.  3. Configuration of the defect. If the welding joint isn't flat then die penetration is the best, otherwise a vacuum test can be used. Also for inline pipeline inspection, if the pipeline is flat, we can use magnetic particle testing, but if the pipeline has bends, then PIGs tools are the preferred.