A solution, known as XHab™, has been developed for external repair and reinforcement of pipelines using ultra high strength steel strip. This method involves wrapping multiple layers of strip in a helical form continuously over an extended length of pipeline using a dedicated forming and wrapping machine. The reinforcement provided by the strip can be used to:
a) Restore the original maximum allowable operating pressure to a section of defective pipe (e.g. external corrosion or denting), or
b) Reinforce an intact but de-rated section of pipeline (e.g. a Location Class change through encroachment) to maintain reduced hoop stress in the base pipe as required by codes and regulations, but allow reinstatement of the original operating pressure by carrying the additional load in the strips.
This paper describes the full-scale qualification testing, including in-field proving runs, and design analysis necessary to demonstrate the field-readiness of the application system and reinforcement product. This includes wrapping and pressure testing of pipe with machined external wall defects. The potential for XHab repair of stress corrosion cracking (SCC) is also discussed for an upcoming series of tests on pipe samples with electrical discharge machined notches.
To demonstrate reinforcement of intact pipe, a 40ft joint of 26-inch vintage flash-butt seam welded pipe, instrumented with hoop and axial strain gages, has been wrapped by the XHab machine with sufficient reinforcement to simulate a change from Location Class 1, Div. 2 to Location Class 3 (ASME B31.8). This pipe has been subjected to pressure cycling and ultimate burst alongside an identical unwrapped pipe sample which provides a baseline. The test results are presented and compared to finite element analysis.