Laser-Ultrasonic Wall Thickness Gauges

MONTREAL–based Tecnar, a supplier of sensors for advanced process control, has successfully implemented more than a dozen laser-ultrasonic wall thickness (LUT) gauges in various seamless steel tube mills around the world. The capacity to deliver precise wall thickness data directly comparable to handheld, cold, UT measurements even over a mandrel and without any hazardous radiation has fuelled the industry’s interest for this technology over the past 15 years.

However, operating advanced optics and lasers in the close environment of 1,200°C steel tubes circulating at over 5m per second and bouncing around by several centimetres has proven to be quite a challenge to the technology’s reliability. Through the development of specialised high power UT detection lasers as well as the implementation of numerous reliability features resulting from extensive in-situ experience, including remote system monitoring and maintenance, Tecnar has managed to achieve reliability levels well within the industry’s very demanding standards.

The company has installed LUT gauges at the output of various mills such as mandrel mills, reelers, rotary sizers, stretch-reducing mills and even hot pilger mills. The data has proven invaluable to operators who can immediately detect and correct process problems, such as piercing eccentricity, heavy centre wall and heavy ends.

(This article was originally published in ITATUBE Journal – Nov 2012)