Is Calibration Of NDT Equipment Necessary?

Is calibration of NDT or any other equipment necessary? The answer is certainly Yes! But a question still arises? Why? Because in the case of NDT it is required by national and international standards. Many NDT standards require that a system of periodic calibration and maintenance must exist for any facility that performs nondestructive testing. For instance, ASTM E-1212 Section 9.2.2 mentions that all measuring and test equipment shall be calibrated and controlled to ensure accuracy of measurement of products and processes to a specified requirement. So why would we even need to ask the question? Because many institutes and research organizations do not have periodic calibration and maintenance programs and are not required to have such programs except for safety related work!