Preloaded bolted connections made of stainless steel

The application of preloaded bolted connections made of stainless steel is demanded in reasons of serviceability or ultimate limit state, e. g. when used in particularly corrosive environments or in stainless steel structures. However, based on EN 1090-2 the use of bolting assemblies made of stainless steel is restricted to non-preloaded bolted connections for several reasons. Resentment still exists against the application of stainless steel bolting assemblies in preloaded connections due to the expected high preload losses and the problem of cold welding ("seizure"). In addition, there are currently no bolting assemblies available on the market comparable to the DIN EN 14399 standards, which are tested by the manufacturer for suitability for preloading including the application of a calibrated lubrication. The main product standard for high-strength structural bolting assemblies for preloading of bolted connections in steel structures, EN 14399-1, is also limited to the application of bolts made of carbon steel, so that the use is also restricted there. Consequently, procedure tests must be carried out for every application scenario. The presented contribution shall give an insight into the possibilities of the application of stainless steel in preloaded bolted connections in general, and in slip-resistant connections in particular. In addition, assistance and guidance for the approach within a procedure test is given by the "Bolt Tightening Qualification Procedure (BTQP)" as a supplement to the regulations of the DASt-Guideline 024.