The standard specifies the ultrasonic flaw detection (UFD) method of steel pipeline butt ring welds and the classification requirements for the detection results. It mainly covers the application principle, operation steps and classification criteria of the flaw detection results of ultrasonic testing (UT) technology. The standard describes in detail how to identify defects in welds through ultrasonic testing (UT) and classify them according to the severity of the defects to ensure that the mass of the weld meets the relevant technical requirements. The method aims to improve the detection accuracy and Reliability of pipeline welds and ensure the safety of pipelines during use.