Method of Testing an Unbonded Flexible Pipeline

A method of testing an unbonded flexible pipeline comprising a polymer pressure sheath, the method comprising at least the steps of: (a) transmitting an electromagnetic signal along the polymer pressure sheath; (b) seeking one or more reflected signals; and (c) analysing the or each reflected signal to determine one or more characteristics of the electrical permittivity of the polymer pressure sheath. In this way, a non-invasive electromagnetic signal can be generated to be passed along the polymer pressure sheath of the pipeline, and any reflected signals can be interpreted and analysed to ascertain any change in the dielectric properties of the polymer pressure sheath, in particular the presence or existence of one or more discontinuities such as cracks or holes, in advance of possible failure, in particular catastrophic failure, of the polymer pressure sheath. Characteristics of the reflected signal(s) can include distance, extent, etc. of discontinuities along the pipeline. This invention can be applied both to new pipelines during their manufacture and/or instalment, as well as existing pipelines being in situ or in service, thereby providing a single method for analysing all forms of pipelines.