The API 1104 standard, 22nd Edition (July 2021), currently in effect and widely used in pipeline projects, recognizes different methods for automated welding inspection. The most widely used methods in the industry are based on ultrasonic measurement principles or the use of radiography.

In some regions, the preponderance of ultrasonic methods has led to misunderstandings and confusion regarding the acceptability of other techniques. Particularly, the use of automated digital radiography (referred to as «Automated Radiography» or AR) is explicitly stated as a valid method for the inspection of circumferential welds. This is detailed in Appendix A («Alternative Acceptance Standards») of the API 1104 standard, where it is defined that any imaging technique—including digital RX (DR), computerized radiography (CR), or AR—is accepted if it meets the established performance, resolution, coverage, and sensitivity criteria.

Treatment of indications: an integrated and engineering-based approach

When an unaccepted discontinuity is detected in the images obtained by AUT RX, the process does not stop at the automatic rejection of the weld. In accordance with modern and internationally recognized integrity management practices, a specific evaluation of the indication can be applied through:

1. Localized complementary inspection, for example with conventional UT or phased array, to determine the precise location of the anomaly within the thickness.
2. Subsequently, an Engineering Critical Assessment (ECA) can be performed, following regulatory procedures (such as API 579 or BS 7910), to determine the structural acceptability of the anomaly based on its type, size, location, and the pipeline’s operating conditions.

This approach allows for decisions based on engineering.