Hydrostatic testing (hydro-testing) of high-pressure gas pipelines is used to evaluate the integrity of the pipe walls, joints, and welds. During hydro-testing, the pipeline is evacuated of gas, filled with water, and pressurized. Since water is heavier than the natural gas that is normally transported in the pipes, the spans of above-ground pipeline segments are subject to increased loading and may require temporary support during testing.
SAGE designed, programmed, and installed a data acquisition system (DAS) to monitor four above-ground pipeline spans along a high-pressure natural gas pipeline during hydro-testing. The DAS consisted of strain gages, thermistors, and displacement transducers to measure pipe strains, temperatures, and deflection along the spans. Dataloggers housed in all-weather cases recorded the pipeline strain and defection data. Prior to monitoring, SAGE performed structural analyses using typical design values and assumptions to predict theoretical stresses and the need for temporary supports to avoid overstressing the pipes. Following hydro-testing, we compared the recorded data against our theoretical predictions. The results were used to identify potential adjustments to design assumptions that can lead to more efficient and cost-effective analysis of pipe spans during hydro-testing and design of temporary pipe support structures.