Pipeline transportation, as an efficient and specialized mode of transportation, plays an increasingly significant role in oil and gas transportation and other fields. Currently, large-diameter transportation pipelines in China are primarily composed of spiral welded steel pipes. To ensure the reliable operation of these pipelines, the quality of the spiral steel pipes used must be strictly guaranteed. Therefore, it is necessary to conduct non-destructive testing on the welds before the steel pipes leave the factory to eliminate potential hazards.
An effective method for detecting welding defects is using pulse-echo ultrasonic inspection technology. Since the primary purpose is to determine the presence of defects, an A-mode (A-scan) ultrasonic flaw detector is utilized. This instrument leverages the reflective properties of ultrasonic waves. On the fluorescent screen, the vertical axis represents the amplitude of the reflected echo, while the horizontal axis represents the propagation time of the reflected echo. The size and location of defects are determined based on the amplitude and time of the defect-reflected wave. Specifically, the R wave represents the reflection from the workpiece surface, F represents the defect wave, and B is the bottom reflection wave.
The automatic flaw detection system comprises an ultrasonic flaw detector, which is integrated into the overall system alongside a transport vehicle and a weld tracking mechanism. The ultrasonic flaw detector is used for weld inspection. Here, six inclined probes symmetrically distributed along the circumference are employed to detect defects in the weld, such as pores, cracks, slag inclusions, incomplete penetration, and unfused platforms. The transport vehicle facilitates movement. During testing, the steel pipe is placed on the transport vehicle and conveyed to the bottom of the weld tracking system. The carriage moves forward while simultaneously rotating the steel pipe, combining these two motions into a spiral movement of the pipe. Ideally, the feed and rotation of the steel pipe must be strictly synchronized. When the spiral angle of the steel pipe weld remains constant, the weld remains strictly within the detection range of the flaw detection system. The weld tracking system serves as a carrier for the ultrasonic flaw detector, tracking the center of the steel pipe weld. To ensure the accuracy and reliability of the inspection, an ultrasonic probe system needs to be installed on the weld tracking system.
On the contrary, X-ray detection technology boasts numerous advantages over the aforementioned techniques. X-ray equipment can not only detect invisible welds in various welded pipes but also intelligently analyze the inspection results, providing an effective detection method for achieving the goals of "first-time pass rate" and "zero defects."
Therefore, X-ray equipment is frequently used for testing. It employs X-rays to penetrate opaque materials, forming a clear and visible perspective view for examining welding quality. For products that cannot be visually inspected, X-ray equipment penetrates materials of different densities to reveal the internal structure of the object being tested, allowing for observation without damaging the object. This technique can pinpoint problematic areas within the test subject. Currently, inspection projects using X-ray equipment primarily include defect inspection in IC packaging, misalignment or bridging and open circuit failures, SMT solder joint inspection, examination of potential abnormal connections in various connecting lines, and verification of solder integrity.
