Method of ultrasonic flaw detection of seamless steel pipe

The methods of non-destructive testing of seamless steel pipes mainly include: ultrasonic testing method, eddy current testing method, magnetic flux leakage testing method and magnetic particle testing method, of which the last three methods can be merged into electromagnetic testing method.

Characteristics and application of ultrasonic flaw detection method for seamless steel pipe:
Due to the characteristics of shape and geometric size of seamless steel pipes, shear wave reflection method is generally used for flaw detection. According to the coupling method between the probe and the surface of the pipe, it can be divided into two basic methods: the contact method and the water immersion method.

1. Contact method for flaw detection
The contact method refers to the method in which the probe is in direct contact with the surface of the pipe for flaw detection. It is generally operated manually. This method has a slower flaw detection speed, but the equipment is simple, easy to operate, and easy to debug when changing specifications. Therefore, in the case of small batches and many specifications is still frequently used.

2. Flaw detection by water immersion method
The water immersion method refers to a method in which the probe is not in contact with the surface of the pipe, and water is used as the medium between the two. Water immersion flaw detection has the following advantages: it can use a focused acoustic beam, so it can significantly improve the detection sensitivity, resolution and ability to detect small diameter pipes, which is convenient for mechanization and automation; because it solves the problem of probe wear and uses cheap coupling media , so the production cost can be reduced. Therefore, the water immersion method has been widely used in the inspection of large quantities of pipes.

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