Typical acceptance criteria for ultrasonic testing of ASTM A269 materials usually involve the following aspects:
Defect size
- Generally, the acceptance criterion for the size of planar defects (such as cracks) is often based on the allowable defect size specified in relevant standards or engineering drawings. For example, a defect with a length greater than a certain value, like 3 mm, may be considered unacceptable. For volumetric defects (such as pores), the allowable size is also strictly controlled. If the equivalent diameter of a volumetric defect exceeds a specific limit, such as 2 mm, it may not meet the acceptance criteria.
Signal amplitude
- The amplitude of the ultrasonic signal corresponding to the defect is an important indicator. Usually, if the signal amplitude exceeds a certain percentage of the reference signal amplitude, the defect may be regarded as unacceptable. For example, when the defect signal amplitude is more than 50% of the full – screen height (FSH) and exceeds the set alarm level, it may indicate a non – conforming defect.
Defect location and distribution
- The location of the defect within the material is also considered. Defects located in critical stress – bearing areas or near the surface are often more likely to be unacceptable than those in non – critical areas. In addition, the distribution of defects is important. If there are a large number of closely – spaced defects or a cluster of defects, it may lead to the rejection of the material, even if the individual defect sizes are within the allowable range.
It should be noted that the specific acceptance criteria may vary depending on the specific application, customer requirements, and relevant industry standards and regulations.
