Inbuilt LED indicator for simple verification of bolt load on site.
LoRa wireless communications to transmit data to the InterBolt tablet for onsite monitoring and InterBolt Gateway for remote monitoring.
Calibrated, high accuracy bolt load sensor.
Battery to power InterBolt for up to 15 years.
Temperature sensor for correlating changes in bolt load with thermal expansion/ contraction of bolted connection.
InterBolt for bolt load monitoring
There is widespread agreement that the best way to ensure high integrity of bolted connections is to measure the bolt load. Historically, direct measurement of bolt load has required technicians to be on-site and the use of expensive, wired and fragile instrumentation so was unfeasible for many applications.
InterBolt features a high accuracy bolt load sensor embedded directly into the bolt or stud.
The technology provides:
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Real-time bolt load measurements to technicians during installation to ensure bolts are tightened accurately and repeatedly
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Remote monitoring of bolt load which eliminates the need for manual periodic inspection
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Continuous and high accuracy bolt load measurements to predict bolt failure, enabling preventative maintenance to be conducted.
How does it work?
InterBolt measures bolt load through measuring the elongation of the fastener under load.
Although it may seem counterintuitive to many, a bolt acts like a spring and is designed to stretch a small amount as it is tightened. This inherent bolt spring tension causes the clamping force which holds the joint together and prevents loosening during operation. The relationship between force and elongation is constant until a bolt reaches its yield point.
The sensing technology embedded in InterBolt measures bolt elongation (through the use of a gauge pin principle) and converts this to an accurate measurement of bolt load (otherwise referred to as clamping force). Every InterBolt is calibrated over its full load and temperature range so no on-site calibration is required.
The InterBolt sensor is also not impacted by changes in effective length so it can be used without configuration for a specific bolted connection. This applies to both bolts and studs, and is a feature which is completely unique to the InterBolt product.
LED indicators
InterBolt features super bright LED indicators for simple and fast validation of bolt load. Simply wake up the device using a magnet and then look at the LEDs:
Flashing red – Bolt load too low
Flashing green – Bolt load in target range
Flashing Red/Green – Bolt load too high
Solid red- Bolt load is above proof load of the fastener and permanent elongation of the fastener is possible.
The LED indicators enable bolt load validation in seconds without the need for heavy or cumbersome tools, an external power supply and complex setup procedures. Even without a clear line of sight to the end cap, the LED indicators can be seen from 20m away.
Onsite bolt load monitoring
As well as the embedded LEDs, InterBolt can connect to the InterBolt Tablet during tightening activities to visualise bolt load. The InterBolt Tablet solution enables bolt load measurements from multiple sensors to be visualised in real-time.
The connection between InterBolt and the tablet is over the LoRa wireless network. The wireless communications still operate when used in conjunction with bolt tensioners or similarly obstructive tools.
Remote monitoring
InterBolt periodically transmits bolt load data to a remote network via the InterBolt Gateway. This enables remote access to real-time, autonomous bolt load samples, eliminating the need for technicians to be on-site.
Each InterBolt Gateway can connect thousands of InterBolts and is typically limited by the range of the wireless network (typically 1km), rather than the number of devices.
In the InterBolt Cloud, bolt load samples are:
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Stored.
Bolt load samples from installation to decommissioning are stored so a full historic overview of the bolt life is known.
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Analysed.
The cloud system features simplistic analytics engines which can generate an alert when the bolt load exceeds a predefined threshold or is trending towards a certain state.
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Visualised.
The cloud features a huge range of visualisation options: from visualising the bolt load from a single sensor, to overlaying the status of bolts on a 3D model of the asset.
Battery life
InterBolt features a battery solution in the end cap. The battery can power InterBolt for up to 15 years, with no maintenance required.
Once the battery is depleted, it can be exchanged as part of the end cap in less than 30 seconds without the need to loosen the bolt. Simply remove the two end cap screws and replace the end cap.
Wireless range
InterBolt utilises LoRa wireless communications to transmit bolt load data to the InterBolt Gateway for remote monitoring and InterBolt Tablet for onsite monitoring.
LoRa uses an optimised modulation technique (spread spectrum) for long range, low power wireless communications. InterBolt couples a LoRa PHY level with a high efficiency antenna and a self-learning adaptive channel optimisation protocol. The result is a wireless range of up to 1km, whilst still having a battery life of up to 15 years.
Through having a long-range wireless solution, typically only one InterBolt Gateway is required to get full connectivity over an asset. Other solutions often have much lower wireless range which results in additional hardware costs for multiple gateways/repeaters and additional deployment cost and effort to provide power to each of these.
Accuracy
InterBolt features the best-in-class sensor accuracy at 95%. The maximum 5% error includes errors due to hysteresis, non-linearity and repeatability. The proprietary bolt load sensor inside InterBolt features component ageing and temperature compensation so InterBolt will maintain its specified accuracy over the full operational temperature range and over its full operational life.
For applications that require higher accuracy, InterBolts with 97% or 99% accuracy can be supplied.
Each InterBolt is calibrated at manufacture over load and temperature, and is supplied with a calibration certificate.
The InterBolt sensor meets and exceeds ASTM F2482 – Standard Specification for Load-Indicating Fasteners.
Dynamic load monitoring
InterBolt can measure bolt load at up to 250Hz whilst the asset is operational. This allows users to measure any cyclic loading in bolted connections to assess whether fatigue failures are likely.
This feature is enabled on all InterBolts manufactured since Q1 2025.
The sampling frequency and interval is configured using the InterBolt Tablet.
InterBolt end caps
InterBolt is available in three end cap variants to ensure compatibility with almost any application:
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Small diameter wireless
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Large diameter wireless
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Mini hardwired
The small and large diameter end caps are completely standalone solutions as they feature wireless communications, LED indicators, battery and processing.
The mini hardwired end cap can be connected to a wireless or wired network using the respective wireless or wired bridge.
Bridges
The mini hardwired end cap can be connected to either:
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A wireless bridge (right) for full integration into the InterBolt LoRa ecosystem.
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A wired bridge (left) to connect InterBolt into an existing hardwired network. A RS485 Modbus bridge is available off the shelf, with CAN and RS232 solutions available as specials.
Any bolt, any stud, any industry
InterBolt is available in a wide range of bolts and studs. Whilst it is typically applied to large diameter fasteners – M16 or 5/8’’ and bigger, the technology has been applied to bolt diameters down to M10.
InterBolt is often embedded into free-issued bolts from our customers but InterBolt can also supply the fasteners through approved European suppliers.
