Abstract
After tightening a bolt, technical knowledge on how far the thread of the bolt should protrude from the nut is not organized. Therefore, in addition to the surveys of existing standards, surveys were conducted in consideration of thread strength at bolt tightening, sealing performance of flange joints, and corrosion. As a result, it was found that the protruding length of the screw thread of the bolt had little influence on the strength of the screw and the sealing performance of the flange joint. However, if it is below flush with nut face, there is a possibility of promoting corrosion by dust and moisture, so one or more protrusion lengths may be required.
