During inspection of small bore NPT threaded fittings, it is often discovered that the number of threads engaged in the fitting is less than the typically specified minimum engagement allowed. This leads to concerns regarding the maximum allowable working pressure (MAWP) for the connection. In this study hand calculations, elastic-plastic finite element analysis and experimental verification were performed to provide guidance as to the MAWP of small bore NPT threaded connections that have between 2 and 5 threads engaged. The goal of the study was to determine a set of criteria for defining whether immediate action must be taken in rectifying the thread engagement deficiency or whether action may be taken on a planned basis.

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