A critical bolted joint in a nuclear power plant requires a specific bolt preload. The access prevents a direct, accurate measurement of the actual bolt preload. It is planned to use a UNF 7/16-20 bolt with a root diameter of 0.3725in. thread angle 30 deg. A test program determines the following values for friction for the specific fastener and application: Threads u= 0.12 Bolt Collar uc= .12. Torque coefficient K=.152
What is the required torque for an initial bolt preload or initial clamping load (P) such that the joint will still have 1000lb final clamping force (Fc) with an external applied load (Fe) of 12000 lb with kc=5kb