The ST100 electromagnetic ultrasonic dual‑wave bolt stress meter employs in‑situ axial‑force measurement technology based on electromagnetic ultrasonic dual‑wave principles. It can assess the preload of high‑strength bolts in service without requiring knowledge of each bolt’s initial condition. During measurement, no coupling agent is needed, and no surface preparation—such as grinding—is required; it can directly measure bolts with raised markings on the head, thin‑diameter double‑ended studs, bolts with internal hexagonal sockets, and bolts with recessed surfaces. This instrument is widely used for verifying the preloading torque of bolts after installation in large‑scale equipment under construction, addressing bolt‑related failures in operating machinery, supporting validation of bolting procedures, and conducting routine inspections of bolt axial forces in in‑service large‑scale equipment.

Product Introduction
☆ The world’s first electromagnetic ultrasonic longitudinal–transverse wave dual‑mode tensile testing device (Patent No. ZL201810893704.4)
☆ Equipment operating conditions:

Power supply: (field-replaceable, rechargeable) Rechargeable lithium-ion battery; standard configuration includes two batteries, each with a capacity of 74 Wh. Charger input voltage: 100–240 VAC, 50/60 Hz; output voltage: 8.4 V, 2 A DC.

Location of Use: Indoor and Outdoor

Ambient temperature: -40°C to 50°C

Ambient relative humidity: 5% to 95%, non-condensing

☆ Main Functions of the Equipment

     1. Utilizing electromagnetic ultrasonic dual‑wave in‑situ axial force measurement technology, this method requires no coupling agent and can measure the axial forces of bolts in service without needing to know the initial condition of each bolt. When the dual‑wave method cannot be applied, it also offers a single‑wave approach that enables direct or indirect accurate measurement of bolt axial forces. It supports standard bolts (studs) as well as wind‑turbine anchor bolts with lengths exceeding 6 meters.

     2. It can measure ambient temperature and apply temperature compensation to the measurement results based on the ambient temperature.

     3. Possesses capabilities for managing engineering measurement data, enabling organization of measurement data by project name, unit number, flange number, and bolt number. Can record and store measurement results according to a bolt-numbering scheme, timestamped by measurement time; stored records include bolt number, echo time, acoustic travel‑time difference, preload force, ambient temperature at the time of measurement, and measurement time, among other relevant data. Includes a measurement‑record viewing function that allows on‑device access to measurement screenshots, retrieval of previously recorded measurements, and annotation of measurement results. Also provides waveform‑recording and display functionality with zoom‑in/zoom‑out capabilities.

     4. The display features high-brightness output, ensuring clear visibility even in direct sunlight, and offers both a bright mode and a night mode to accommodate various measurement environments.

     5. The device features standalone testing capabilities, is highly portable and integrated, with the main unit and data display combined into a single compact unit. Its user-friendly button design enables one-handed operation, allowing easy access to tight spaces and rapid completion of test tasks. Physical buttons are used to prevent accidental touches. The device also supports measurements via both mobile and tablet apps.

     6. The equipment is optimized for on-site use, enabling automatic waveform selection, automated result generation, and one-click saving, among other features.

     7. Implement calibration of the batch‑bolt ultrasonic system, i.e., generate calibration curves for acoustic time difference and preload force, enabling the use of an average calibration curve for multiple bolts.

     8. When no bolt calibration file is available on site, the bolt axial force can be calculated using the onboard database based solely on parameters such as the bolt’s initial value and slope.

     9. The host unit is capable of directly calculating or back-calculating axial force based on the measured waveform and the calibration file.

    10. Equipped with dual‑wave inspection functionality: provides long-term on-site monitoring of bolt axial forces with accuracy better than 1%.

    11. Upon submission of on-site full‑machine test data by the user, the manufacturer may provide bolt cloud services, with fees to be negotiated separately.

    12. The Bolt cloud service includes multi-device data synchronization, management and sharing, automated report generation, database calibration, and other features.

13. Bolt Yield State Monitoring Based on Bolt Cloud

    14. Bolt axial force early warning, supporting digital operations and maintenance through “testing in lieu of inspection”