NDT standard reference blocks, which are frequently  designed and made to test pieces used in Non Destructive Testing Services (NDT) to calibrate, verify, and optimize the performance of NDT equipment and techniques. These blocks are made of materials that closely match the qualities of the parts or structures being inspected, such as metals, plastics, or composites.

Their main purpose is to act as a standard against which the sensitivity and accuracy of NDT tools and methods can be measured. NDT workers use reference blocks to check the functionality of instruments like ultrasonic, radiographic, magnetic particle, and dye penetrant testing equipment. By comparing the signals and responses from the reference block to known flaws or features in it, technicians can make sure that their NDT equipment is calibrated properly and can accurately find flaws or breaks in real-world parts or materials.

In the end, NDT standard reference blocks are an important part of quality assurance because they help NDT professionals keep the integrity and reliability of their inspections and make sure they meet industry standards and specifications.