ERREKA Fastening Solutions, a cooperative company fully integrated in the Mondragon Group, is a reference Company as far as specialists in critical bolted joints are concerned. We have been developing engineering projects to improve bolted joints and manufacturing special bolts/studs for critical applications since 1961. Small presentation of our complete proposals related bolted joints: 1) Engineering Projects to improve bolted joints: We develop projects to improve the design, tightening, assembly, maintenance or the security of the bolted joints for critical applications. Please, find below a small summary of the kind of projects: • i-bolt®: ultrasonic resident sensor for direct reading of the tension of the bolt. This allows us to know the preload of the joint at tightening and also during the life of the bolt with +-3% of accuracy. This could be a solution to reduce risks (leakages,…) in critical bolted joints. • Design of tightening strategies to assure optimal assemblies. • Computer joints simulations, real tests… • Validation of the bolted joint and the tightening strategy. • Projects to find failure root causes in bolted joints and proposal of solutions. 2) Production of special bolts & stud bolts for critical applications. We manufacture special bolts & stud bolts for critical applications with high quality standards. Our production is specialized in medium – large dimensions according customer drawings or specifications.