Introduction
Hydrogen production by electrolysis relies on complex systems exposed to high mechanical, thermal, and chemical stresses. Tie rods ensure the mechanical integrity of the electrolyzer. Depending on the design, an electrolyzer may include between 10 and 30 tie rods, and their tightening is critical for both performance and safety.
Traditionally, manufacturers use hydraulic tensioners to apply a target load, usually around 1000 kN. However, after just a few operating cycles, significant relaxation can occur—sometimes down to 700 kN—caused by pressure and temperature fluctuations. This represents a drop of nearly two-thirds of the initial preload.
The challenge of bolt relaxation
Insufficient tightening can lead to:
- a loss of energy efficiency,
- increased leakage risks,
- premature component wear,
- and even safety incidents.
This makes continuous bolt tension monitoring essential, beyond the initial tightening operation.
The contribution of the TRAXX-M2 ultrasonic bolt tension meter
The TRAXX M2, a portable and compact device for bolt load measurement, offers an innovative solution.
Its principle relies on ultrasound: the sensor measures the time-of-flight of an ultrasonic wave through the tie rod. As the rod elongates under tension, the variation in wave travel time is used to precisely calculate the actual bolt load.
The results are clear: the TRAXX M2 achieves a measurement uncertainty of only ±2 to 8 %, compared to ±20 % with hydraulic tensioners, and up to 30–50 % with torque tightening. This precision gives the ultrasonic bolt tension meter two key advantages: first, optimizing tightening during installation or maintenance; second, enabling continuous monitoring over time to anticipate relaxation and prevent failures.
A solution tailored to the hydrogen sector
The TRAXX M2 works on tie rods of all sizes, operates across a wide temperature range, and withstands demanding industrial environments.
It integrates perfectly into electrolyzer maintenance programs, typically carried out every two years.
For operators, the technology provides a triple guarantee: improved performance, longer durability, and enhanced safety. It ensures optimal tightening, avoids premature failures, extends the service life of electrolyzers, and strengthens overall plant safety. Beyond these technical benefits, there is also a direct economic impact: fewer unplanned shutdowns, reduced repair costs, and ultimately, higher profitability.
Conclusion
Who would have thought that tie rods—seemingly simple mechanical elements—could play such a critical role in the energy transition?
With advanced bolt load measurement and bolt tension monitoring, the production of green hydrogen becomes more reliable, safer, and more sustainable. A clear demonstration that innovation, even in mechanical details, can profoundly transform the hydrogen industry.
