The testing of screws with threads up to M39 is defined by the ISO 898-1 standard. For threads larger than M39 (Fmax > 1200 kN), ZwickRoell offers proven solutions based on ISO 898-1. The various test methods specified in the standards are already preprogrammed in the testXpert III testing software. Also, the minimum break forces required by the standard are stored in the testing software and are compared to the test results, enabling efficient and reliable testing. To assist with gripping the specimen in the testing machine, self-aligning tension grips with head mountings and threaded mountings are used, which ensures compliance with the minimum specimen length specified in the standard. For performing strain measurement on screws, the makroXtens extensometer is used. The sensor arms can remain on the specimen until after break whereby an automatic determination of strain at break A is possible. When combined with the corresponding mandrel and die, the self-aligning tension grip can also be used to perform proof load tests (tensile and compression tests) on nuts according to ISO 898-2. The nut is loaded at the force specified in the standard and maintains it for 15 seconds. The nut is considered to have passed the test if the nut can be twisted off manually from the mandrel.