| 摘要 |
Fluid transmission lines in a submarine or hazardous environment are provided with substantially fluid tight seals by the formation of a temporary ice plug within the interior of the line using a housing forming a cryogenic fluid circulation chamber installed around the exterior of the line. Remote controlled valves are interposed in separate conduits for supplying fluid to chambers formed within the housing, venting fluid vapor from the chambers, recirculating liquid cryogenic fluid back to a reservoir and for purging sea water from the chambers formed by the housing. The remote controlled valves are preferably controlled from a service vessel on the water surface or from within a submarine habitat. Conduit assemblies are provided with self closing quick disconnect connector assemblies whereby the service vessel containing a source of cryogenic fluid and a control station may abandon the work site during heavy sea conditions. The operating sequence for installation and freezing of the temporary plug includes installation of the housing forming the fluid circulation chamber by skilled divers followed by purging of sea water from within the chamber using compressed air or cryogenic fluid in gaseous form. Cryogenic fluid pressure within the chamber formed by the housing is preferably maintained at a pressure slightly greater than the hydrostatic sea water pressure at the location of the housing on the transmission line so as to minimize stress on the housing structure and to minimize the chance of leakage of sea water into the housing chambers.
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