A connection with know-how
Bolted connections are the most important connections in the industry. Modern calculation programs make it possible to design machines and installations ever lighter and with smaller safety margins. Materials are hereby subjected to higher loads, closer to the physical limits of the material. This requires a more accurate and stable bolt load in bolted connections.
More than 99% of all industrial bolted connections are brought to preload by applying torque. Usually, the criterion of a desired end-torque is used. However, other methods such as torque and angle and yield controlled methods, are increasingly being used to preload bolts at higher levels and to exploit more potential from the strength of the material. To meet these demands, the bolting industry is developing tools that are more sophisticated than ever.
In addition to good methodology, the demand for documentation of the bolting process as proof to clients and insurance companies. Fully automated processing of a tightening protocol (entered in advance) minimizes the risk of operator errors. To better detect the event of material- and construction errors, there is a trend in critical applications to use a second parameter as a check on the first (VDI 2862-2). This is commonly referred to as the control parameter.
We explain the most important and frequently used bolting methods below.