Why does a Grade 8 bolt sometimes break during installation when it is used with a prevailing torque locknut?
Many prevailing torque locknuts are supplied with a coating of industrial grade wax on them. The wax acts as a lubricant to overcome the friction caused by the locking element or the distorted threads. Often, less wrenching force is required when assembling these waxed locknuts than when assembling a bolt with a regular non-locking nut. If a bolt breaks during assembly, chances are that they have been tightened much too much. Contact your fastener supplier, who should be able to advise proper assembly torque when using lubricated locknuts. Remember , too, that a torque wrench should also be used.
