| 摘要 |
ICR 8242 In a pipeline crossing, a carrier pipeline is annularly surrounded by a casing with the ends of the casing vented to the surface and sealed with the periphery of the pipeline to minimize corrosion of the pipeline wall, Access and pressure relief valves are provided on the casing vents at opposite sides of the crossing. This permits purging of the casing injecting an inert gas under pressure into the casing annulus through the valve equipped vents to provide a protective fluid, and periodically monitoring the gas pressure. The gas is maintained at a low pressure which is substantially less than the pressure of product materials within the pipeline. |
