AMTEC Assembly Equipment
Hydraulic Tensioning
In the case of safety-related components, e.g. in nuclear power plants, we rely on the hydraulic clamping method, since friction effects are of secondary effect and there are practically no torsional stresses in the bolts.
All bolts in a joint can be tightened at the same time, eliminating the need for a complicated tightening sequence.
In addition, the elements of the connection - especially the sealing elements - are loaded beyond their subsequent preload. Setting and relaxation processes are thus accelerated and have subsided at the end of the clamping process.
Monitoring of the Bolt Stress
In order to control the level of the resulting bolt stresses and to narrow the scatter band of the stress, an explicit measurement of the bolt stress may be necessary. Therefore, in addition to the hydraulic clamping devices, we have developed various systems that allow a complete control of the clamping process.
Under the product name TEMES fl.ctrl we manufacture hydraulic tensioners for the assembly of flange connections, which can be used either as individual clamping cylinders or as a complete system.
The TEMES okto.mu system is used to measure bolt elongation. The elongation is proportional to the applied force - the relation can be calibrated.
To use this system, the bolts of the joint need to have an intenal pin. Fixed only on one end, the pin maintains its original length while the bolt is elongated when load is applied.
The bolt elongation can be monitored and controlled during the entire tightening process by use of digital dial gauges. The dial gauges are placed directly on top end of the tension nuts.
The dial gauges are equipped with a radio transmitter, so the data are transmitted wirelessly to the data acquisition system.
All stages of the tensioning process can be checked on the screen of a connected notebook/tablet.
This allows individual bolts to be adjusted in a controlled manner and the resulting preload can be achieved with high precision.
At the end of the tensioning process, the quality of the assembly can be documented.
