Development of a Testing and Analysis Framework for Validation of Rehabilitating Pipe-in-Pipe Technologies

Abstract

Aging natural gas pipeline infrastructure needs rehabilitation, and trenchless, pipe-in-pipe (PIP) technologies offer a versatile solution. For example, legacy cast/wrought iron pipes have been subject to elevated incident rates for decades (www.phmsa.dot.gov). In an effort to accelerate innovation, the United States (U.S.) Department of Energy (DOE) has invested in a recently initiated, 3-year research program focused on pipeline “REPAIR”. To establish industry adoption of new technologies, a robust framework to evaluate and validate systems under in-service loading conditions is required. This paper introduces the approach taken by the Testing and Analysis team to develop a framework that confirms a 50-year design life for the PIP technologies. Testing protocols involve a comprehensive literature review, performance criteria, and relevant load cases and failure modes of PIP technologies. We use numerical and analytical modelling to investigate failure modes and severe conditions, thus informing testing protocols. In this paper, we discuss analytical frameworks and proposed model validation methods. We further discuss plans for test geometries (e.g., circumferentially cracked host pipe) and protocols (e.g., cyclic/dynamic traffic loading) to apply relevant load cases and probe failure modes in service. Modifications and enhancements are investigated in light of the insights gained from review and modelling. The testing and analysis framework for validating service life performance of trenchless PIP repair methods is intended to accelerate the development and adoption of new and safe repair technologies in the gas industry, as well as other critical lifeline systems.