Customer Requirements Analysis

Many of our customers are manufacturers of raw material pipes such as steel pipes and PE pipes. They need to strictly control product quality during the production process. The current method for the long round pipes produced is to use calipers or micrometers or ordinary ultrasonic thickness gauges to measure the wall thickness. Since the round pipe is relatively long, the current test instrument cannot test the wall thickness except for the two ends, which will cause great security risks in subsequent use. And the traditional test method is slow and inefficient, which can’t meet production needs.

Product Application and Quality Control

In order to have a sufficient service life, the steel pipes in service need to ensure their minimum wall thickness. The maximum wall thickness and minimum wall thickness of the steel pipe used as the shell of the mobile pressure vessel such as the gas cylinder should be strictly controlled in order to ensure its bearing capacity and loading capacity at the same time. The thickness measurement that satisfies the thickness control at all positions of seamless steel pipe is called full-length thickness measurement or 100% thickness measurement. After making gas cylinders and other products, it is necessary to measure the thickness of key parts at fixed points.

Principle of Ultrasonic Automatic Thickness Measurement

Basic principle of ultrasonic thickness measurement: the time between the initial pulse and the first bottom wave is measured by the pulse reflection principle and multiplied by the sound speed to obtain the measured value of wall thickness. Ordinary portable ultrasonic thickness gauges can only be connected to one ultrasonic probe and use contact coupling to perform manual single-point measurement, which is low cost but low efficiency for batch measurement.

Application of Multi-Channel Measurement

In automatic thickness measurement, in order to improve the detection speed, multi-channel instruments are often used. When measuring different materials, as long as the appropriate probe and coupling method are selected and the correct sound velocity value is set, the correct thickness value can be measured.

The multi-channel option of YUSHI PM5 Gen2 instrument is equivalent to one unit equipped with multiple ultrasonic probes for thickness measurement. The thickness values of multiple points can be measured and displayed simultaneously through multi-channel software and external multi-channel converters. Through the real-time measurement software of the upper computer, the real-time measurement interface can be viewed on the PC side. Parameter Settings (probe type, measurement mode, etc.) and waveform adjustment (gain, gate, blanking, etc.) can be adjusted independently to meet different measurement requirements. Multi-channel real-time measurement software of the host computer and secondary development library functions are included, suitable for online measurement and secondary development.

Technical Points of Ultrasonic Automatic Thickness Measurement

Coupling Method

According to the structural characteristics of the mechanical equipment, the local water immersion method, water spray probe method, and delay line method are used respectively. Due to the large attenuation coefficient of the delay block material, delay line method is generally used for the wall thickness is not more than 30mm. The typical echo is shown as follows.

Selection of Probe Frequency

The increase of probe frequency improves the resolution, but too high frequency will cause interference of noise signal. Generally, when the wall thickness is 10~100mm, 5MHz frequency is appropriate. When wall thickness less than 10mm, it will be better if the frequency is appropriately increased. For PE material, probe frequency of 1-2.5M is more suitable for measurement.

Measurement Type Selection

The automatic thickness measurement of the entire steel pipe obtain the wall thickness value by using the time between two bottom waves, which can avoid the error caused by the flaw detection system and save the calibration work, making it easier to achieve automatic thickness measurement.

If you want to know more about the application of ultrasonic technology in automated measurement, four-channel, eight-channel and sixteen-channel according to customer requirements can be customized. If you have any problems in measurement, please contact us for providing you with solutions.