Wireless monitoring of tension in critical joints 01 February 2021

Maintenance engineers in critical environments, charged with condition monitoring, have long wished the bolts themselves could start the conversation. Now they can, with Valley Forge & Bolt taking its SPC4 ® Load Indicating Technology to a new level with the UHF Band RTM™ Meter – a wireless bolt monitoring system.

The UHF Band RTM™ Meter operates in 433/868/915 MHz frequencies, which includes the industrial, scientific and medical (ISM) frequency. This wireless sensor detects and collects the tension level in a bolted joint, as read by the company’s SPC4® fastener, and then relays the data to a facility’s condition monitoring/SCADA system. Users can also program the sensor to take measurements at prescribed intervals and send alerts if a bolted joint falls out of chosen tension parameters.

There are several scenarios in which the UHF Band RTM Meter’s capabilities will pay dividends for users. The first is the meter facilitates close monitoring of new fasteners during and immediately after installation. The early hours after an initial tightening sequence can be critical to long-term performance because an unexpected loss of tension can affect bolt life.

“The facility manager can set the reading intervals for rapid readings, down to once every second or for every 10 minutes. They can see immediately if a fastener is losing tension and correct it,” explains James Brooks, head of engineering and business development at Valley Forge & Bolt. “Conversely, after enough time has passed and they are satisfied that the tension is holding, the manager can quickly and remotely adjust the reading intervals to be farther apart.”

In the long-term, all bolts can be set to broadcast alerts when a chosen tension threshold is crossed. “Select a tension percentage that is close to your application’s danger or alert zone,” adds James. “If needed, a window with upper and lower tension percentage limits can be created. An alert can then be sent as an email or as an audible alarm. The user has total flexibility.”

Valley Forge & Bolt states that for the first time, the bolt is starting the conversation about whether it needs maintenance or inspection. Managers can also program alert windows during ‘interest’ periods, such as times of suspected greater vibration in a process, to gauge how fasteners are reacting.

With a web-based user interface, users can change parameters for each wireless sensor remotely. “These features have never before been available in a bolting wireless product,” said James. “The UHF Band RTM™ Meter is a game changer.”

SPC4® fasteners make it possible to measure the actual tension from within a fastener, providing ‘real-time’ knowledge of critical joint tension and performance from installation through a fastener’s life. A variety of sensors and meters are available to read, display, and relay this tension information.

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