SGH performed a condition assessment of the line while in service and proposed and designed repair and replacement of a high-risk section the line. Our investigation included field inspection of the failure site, analysis of stresses in the pipeline, mechanical and metallurgical testing of the prestressing wire and the steel cylinder, electron microscopy of fracture surfaces of wire, petrographic examination of the mortar coating, and chemical analysis of the soil and groundwater.
We determined that failure was the result of a loss of prestress due to hydrogen-embrittled wire near an active corrosion cell, followed by external corrosion and rupture of the steel cylinder. SGH evaluated the risk of pipe rupture and identified a section to be replaced with steel pipe.
SGH evaluated the steel pipe design and interconnection design. We also provided engineering services during live tapping and interconnection construction.