Mitsubishi Heavy Industries, Ltd. (MHI) received an order from JFE Steel Corporation (headquarters: Chiyoda-ku, Tokyo) for an ultrasonic thickness monitoring system that can be used in environments with flammable gases. The system was developed proprietarily based on the world’s smallest and thinnest thin-film UT sensor(Note) technology, which can be installed easily in narrow or curved spaces like underneath insulation or in elbow (curved) joints of pipes. After a series of test operations in the Fukuyama area of JFE Steel’s West Japan Works (Fukuyama City, Hiroshima Prefecture) in March 2022, JFE Steel decided to adopt a large number of the systems in the area as a result of the proof of concept that was achieved.

The ultrasonic thickness monitoring system comprises a thin-film UT sensor that can measure the thickness of pipes or vessels and a Ultrasonic Detector (Pulsar Scope) that can transmit and receive ultrasonic wave through thin-film UT sensor. The system enables significantly more advanced and less labor-intensive maintenance of vessels and pipes handling flammable substances.

The thin-film UT sensor, which comprises cables measuring up to around 20m, can be installed in environments where flammable gas is present, and can accurately measure changes in thickness in an area used for the purpose of securing a structure with glue or similar for around 10 years. There is also a corrective function for changes in sound velocity of ultrasonic waves due to changes in temperature, enabling highly accurate measurement in high-temperature environments up to 200℃. MHI’s explosion-proof thin-film sensor is the first in the world, and many have been developed and used in nuclear and thermal power plants. The pulsar scope, meanwhile, also has a radio transmitter enabling wireless transmission of the data to a computer or other device, allowing personnel to remotely monitor the thickness of devices installed in hazardous areas.

MHI is also currently working to further enhance the functionality of the thin-film UT sensor, including expanding the range of temperatures that can be measured. MHI aims to continue providing new solutions using explosion-proof technology to streamline inspections and monitoring in hazardous areas and contribute to greater safety in plants.

• UT stands for “ultrasonic testing”. A thin-film UT sensor is thinner and more flexible than a standard UT sensor, enabling continuous use in high-temperature environments.

■ Photos of areas where the system is used