During ultrasonic examination calibration, the temperature of the calibration standard should be within how many degrees of the test object?

The appropriate calibration temperature for ultrasonic examination is critical to ensure that the inspection results are accurate and reliable. When calibrating an ultrasonic testing system, the temperature of the calibration standard should closely match that of the test object being inspected. This is important because the velocity of sound in materials can be affected by temperature variations, which in turn can influence the accuracy of the time-of-flight measurements used to detect flaws.

Choosing a calibration temperature that is within 25 degrees of the test object's temperature strikes a balance that accommodates typical variations encountered in the field. This range is sufficient to mitigate the risks associated with significant temperature discrepancies that can lead to erroneous interpretations of the test results.

In practice, exceeding this temperature range could result in variations in the ultrasonic wave propagation velocity, potentially leading to misinterpretation of flaw sizes or locations. The 25-degree specification thus provides a standard that helps maintain the integrity of the inspection process while recognizing the practical aspects of thermal variations during real-world testing situations.