steel tube

    Use of dsaw pipe in following cases:     (1) For the high peak regulation of the pipeline, due to the user's gas consumption is very uneven, frequent fluctuations in pipeline pressure, steel pipe to withstand the large alternating stress, pipe defects have been extended under the alternating stress, if selection of welds, high probability of defects in the spiral welded steel pipe , pipe safety operations will not be guaranteed.     (2) Pipeline crossing the seismic fault zone or through the local high-intensity seismic area, due to the frequent geological activities of these lots, the pipeline will produce longitudinal or axial alternating stress. Spiral weld, the probability of defects is higher than that of dsaw pipe. Under long term stress, the probability of occurrence of spiral welded pipe is much higher than that of dsaw pipe.     (3) Inside and outside the coating requires a high pipeline, should be used dsaw pipe. spiral pipe mo...

    In the ultrasonic inspection of dsaw pipe, how to identify and determine the echo is a key issue. The influence of ultrasonic defect signal or non-defect signal and the radius of curvature of the steel pipe on the defect location is analyzed by analyzing the characteristics of the actual ultrasonic testing of the double-sided submerged arc welded pipe weld, including the segregation, inclusions, crack and base metal delamination of the ultrasonic echo signal. This paper summarizes the causes and identification methods of four kinds of pseudo-defective waves, such as the reflected wave of the coupling agent, the reflection wave of the weld surface, the reflected wave caused by the upper and lower dislocation of the weld, and the non-defect wave formed by the weld height or the undercut The accuracy of the defective wave discriminating provides a new idea and direction for the actual ultrasonic testing of the dsaw pipe.     In the ultrasonic inspection of steel p...