Influence of bonding level on the bending fatigue behaviour of internal replacement pipe systems

Shanika Kiriella, Allan Manalo, Cam M. T. Tien, Hamid Ahmadi, Warna Karunasena, Patrick G. Dixon, Ahmad Salah and Brad P. Wham

Abstract

Internal replacement pipe (IRP) is a novel trenchless repair technology for rehabilitating legacy gas and oil pipelines. The current knowledge of the behaviour of IRP systems under repetitive traffic loading is limited due to insufficient research work. This study aimed to examine how the bonding level between the host pipe and IRP affects the flexural fatigue performance of IRP used for repairing legacy gas pipelines with circumferential discontinuities. The investigation was conducted using numerical four-point bending simulations under both pressurised and non-pressurised conditions. The influence of the thickness and material properties of IRP and the magnitude of traffic loads are also explored. The results of the analyses showed that the minimum fatigue life of all pressurised systems with any bonding level is primarily controlled by the tensile failure of the bottom outer surface of IRP. Based on a loading configuration of 762-1016-762 mm (30-40-30 in), it has been determined that unbonding 311.2 mm (12.3 in) diameter IRP from the host pipe to a length at least equal to the diameter of the IRP from the discontinuity edge provides the longest service life for non-pressurised repair systems. Similarly, for all pressurised systems, the longest fatigue life can be achieved by unbonding them to a length of at least twice the diameter of the IRP from the discontinuity edge.

Key Words

Finite element analysis (FEA); flexural fatigue behaviour; fully bonded; host pipes; internal pressure; Internal replacement pipe (IRP); stress concentration; traffic loading; unbonded

Address

Shanika Kiriella: Center for Future Materials, University of Southern Queensland, Toowoomba, QLD 4350, Australia Allan Manalo: Center for Future Materials, University of Southern Queensland, Toowoomba, QLD 4350, Australia Cam M. T. Tien: Center for Future Materials, University of Southern Queensland, Toowoomba, QLD 4350, Australia Hamid Ahmadi: Center for Future Materials, University of Southern Queensland, Toowoomba, QLD 4350, Australia Warna Karunasena: Center for Future Materials, University of Southern Queensland, Toowoomba, QLD 4350, Australia Patrick G. Dixon: Center for Infrastructure, Energy, and Space Testing, University of Colorado, Boulder, CO 80309, USA Ahmad Salah: Center for Future Materials, University of Southern Queensland, Toowoomba, QLD 4350, Australia Brad P. Wham: Center for Infrastructure, Energy, and Space Testing, University of Colorado, Boulder, CO 80309, USA

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