Multichannel Ultrasonic-Bolt-Tension-Gauge System

An improved system for measuring tensions in multiple bolts is based on the usual measurement of the times of propagation of ultrasonic waves along the bolts, but the quantities measured and the method of processing the measurement data differ from those of conventional ultrasonic bolt-tension gauges. Typically, a conventional ultrasonic bolt-tension gauge utilizes a single particular feature of the ultrasonic waveform (e.g., a single zero-crossing) to measure the round-trip propagation time. When the gauge is functioning correctly, it can measure time with sufficient accuracy to give the bolt tension within ±2 percent. However, sometimes, the gauge focuses on the wrong signal feature (e.g., the wrong zero-crossing), yielding a reading that can be erroneous by as much as ±30 percent.