On the Endurance Limit of Fiberglass Pipes Using Acoustic Emission

This paper proposes a method for determining endurance limits to leakage for fiberglass pipes under internal pressure using acoustic emission signals and static pressure tests. Results are presented from a series of cyclic internal pressure tests performed on fiberglass pipes fabricated according to ASME RTP-1 (1989) recommendations. The specimens were $8in.$$(20.32cm)$ internal diameter and $5ft$$(1.525m)$ long. The construction layup consisted of an internal corrosion barrier followed by several layers of continuous filament wound glass. A state of pure hoop stress was imposed via an internal pressure system that allowed free axial movement of the pipe. The purpose of the tests was to evaluate current design procedures and to assess the capabilities of acoustic emission (AE) monitoring to detect damage and to predict the leakage pressure for the pipes. Twenty-four specimens were tested to failure with AE monitoring. The results of these tests are presented, including data on the measured cyclic life of the specimens, comparisons to the static leakage capacity, and the effectiveness of AE in determining damage induced by cyclic loading.