Abstract
Air-cooled heat exchangers (ACHE’s) that use plug-type header boxes need to be sealed from the plug sheet. During installation it is possible that the internal threads of the header box or the external threads of the plug bolt are stripped thus, compromising the ACHE. The study conducted analysed the behaviour of the internal and external threads of a plug bolt and parent plate manufactured to conform to 1.125 – 12 UN – Class 2A and 2B to ANSI B1.1. The connections were deemed reusable and a torque of 400 Nm was applied to ten lubricated plug bolts, each analysed on a new threaded hole for each plug bolt. It was concluded that the threads deform in an unpredictable manner and may deviate from the standard 60º by either increasing or decreasing from the standard during any tightening. The finite element analysis (FEA) results indicate that the threaded regions are not subjected to stresses that exceed the yield strength of either material and therefore, thread stripping will not occur. The experimental results agree, in this regard, to the FEA results.
M.Ing. (Mechanical Engineering Science)