Patent ID: 7475591

Claim:
A system for hydrostatic testing a selected section of a pipeline having fluid flow therethrough in an upstream to downstream direction, comprising: a first isolation tool introduced into the pipeline having means for being propelled by fluid flow through the pipeline and having means by which the tool may be set at a first selected location and for sealing the pipeline against flow therepast; a second isolation tool introduced into the pipeline a pre-selected time after the introduction of said first isolation tool and thereby a pre-selected distance upstream of said first isolation tool and having means for being propelled by fluid flow through the pipeline and having means for being set at a second selected location and for sealing the pipeline against flow therepast, spacing within the pipeline between said first and second isolation tools forming a test section and containing a test liquid slug; a sealing pig introduced into the pipeline a pre-selected time or distance prior to said first isolation tool for being propelled by fluid flow in the pipeline and providing a leading slug of fluid in the pipeline between said first isolation tool and the sealing pig; a pump for pumping fluid from said leading slug of fluid past said first isolation tool and into said test liquid slug to increase the hydrostatic pressure thereof; and instrumentation for measuring fluid pressure in said test liquid slug.