Robco Expert

Lotfi Grine, Eng. – Product Specialist at Robco   Causes for bolts to loosen in service: ·         Vibration: it’s an unintentional loosening, and it is the repeated relative displacements between the contact surfaces resulting in relative motion occurring in the threads. ·         Gasket creep: the gasket loses its springiness over time; it is also a permanent deformation and It’s more severe in high-temperature applications. ·          Elastic interactions between multiple bolts: Elastic interactions can either increase or decrease bolt preload. ·         Temperature fluctuation caused as a result of either differences in temperature or differences in clamped materials. ·          Low preload developed at installation: it occurs when there is no sufficient clamp force (under-tightened bolt) present on the joint interface to prevent relative motion...

Junction with leak problem, Should I suspect the fastener device...? Jocelyn Vachon - VP Busines development - Robco Uneven Bolt Stress. An incorrect bolt-up procedure or cramped working conditions near the flange can leave some bolts loose while others are overtightened and crush the gasket. This can cause in-service leaks, especially in high temperature services when the heavily loaded bolts relax. in order to close the micropores inside the gasket itself and to fill in the unevenness at the flange facing - gasket interface, the assembly bolt load should be calculated according to the ASME Code. Every bolt has a correct torque/tension elasticity range and a properly tensioned bolt works at its optimum efficiency. If the tension is too low, the nut could vibrate or work loose and if the tension is too high (overstretched), the bolt may yield. That being said, we strongly encourage you to Choose the proper fastener device (Bolts, nuts and washers) for example use a hardened washe...