Non destructive testing (NDT) is the process of analysing assets in a manner which doesn’t degrade or damage them in any way. Principles such as ultrasonics, electromagnetics and acoustics (among others) are used in order to gain information about the asset, without damage. The alternative would involve cutting a sample and either visually inspecting the piece, or sending it for analysis at a lab. Due to the nature of many assets inspected, keeping them online, and avoiding expensive repairs is of high priority. NDT is most often used in industries such as oil and gas, chemical, process, bulk storage, and refining among many more. Feel free to visit their website at Salem Design & Manufacturing, LLC for more details.
The assets inspected and nature of the inspection can vary greatly, with unique applications arising commonly. Typically assets however include items such as pipelines, storage tanks, boiler tubes, condensers, heat exchangers, distillation columns, all the way through to small aircraft parts, and structural welds.
Ultrasonics Testing – Ultrasonics is a common technique employed, providing reliable information, with great precision and accuracy. Ultrasonics can be used to check the thickness of an asset with ease, and giving remaining wall thickness. This is a very common technique, often utilised because of its ability to determine corrosion rates, provide accurate data and the speed of inspection.
Magnetic Particle Inspection (MPI) – This is a great technique for use on welds, or other areas cracking may be of concern. MPI uses high contrast paint, in conjunction with magnetic particles in order to look for very fine cracking and other defects. MPI provides a more hi-tech, modern alternative to more outdated techniques such as vacuum box inspection.
Dye Penetrant Testing (DPI) – Dye Pen as it’s often abbreviated, is another great technique that can look for cracking and other surface defects, this time allowing dye to seep into cracks and other surface breaking defects, and then washing and highlighting the area using a separate paint. Cracks and other defects will hold the dye in, allowing them to be plainly seen once highlighted. Ultraviolet dyes can be used as well for extra visibility.
Eddy Current Testing (ECT) – Eddy Current is an electromagnetic technique that uses an electromagnetic coil to generate eddy currents and a secondary magnetic field within that asset. This allows subsurface inspection to take place, as defects interrupt the magnetic field and cause permeability changes in the original coil. ECT is great for welds, especially in lined tanks, where direct access to the weld is unavailable. Due to the ability to penetrate materials, inspection can be performed through coatings and linings.