FREMGANGSMAATE VED LEGGING AV EN ROERLEDNING PAA EN SJOEBUNN

摘要

A method for maintaining a positive internal pressure in a pipeline while the pipeline is being constructed which comprises initially positioning a pair of releasable sealing devices in spaced relationship within the pipeline and in a releasable pressure tight engagement with the inner periphery thereof, introducing a pressure fluid into the interior of the pipeline between the devices and behind the first of said devices, depressurizing the interior of the pipeline between the devices; moving the second of said devices within the pipeline to a position in the proximity of the open end of the pipeline wherein construction is taking place and engaging the second device in a pressure tight position with the inner periphery of the pipeline; admitting a pressure fluid into the pipeline between the two devices for equalizing the pressure on the opposite sides of the first device; moving the first device in a direction toward the second device to a position immediately behind the second device and re-engaging the first device in a pressure tight arrangement with the inner periphery of the pipeline; and repeating the process as required during the construction of the pipeline.