316 stainless steel hexagonal screw

316 stainless steel hexagonal screw In the project of building nuclear power plants in China, foreign experts guide workers to tighten bolts three times and then retract them half a turn. I believe everyone has heard such a statement before. So, what is the theoretical basis for this statement?In fact, in most high-end mechanical equipment factories, there are strict operation manuals to guide the tightening of bolts when assembling special parts, and there are clear specifications for how much torque to apply. After tightening the bolt, an additional pre tightening force should be applied to prevent loosening, so the pre tightening force will be eliminated after half a turn of loosening. After tightening, bolts are in elastic deformation, especially under high temperature and vibration loads. Prolonged pressure can cause creep, and after the bolt becomes plastic deformed, its strength will significantly decrease or even fail.Turning back half a circle is to restore some elastic deform…