Patent ID: 7854236
Filing Date: 2010-12-21
Classification: F16L,Y10T

Abstract:
1. A method of assembling a vacuum insulated piping run for conducting a cryogenic fluid, said method comprising: producing piping sections in a first location, the piping sections having a concentric arrangement of outer cylindrical casings, inner pipes to conduct the cryogenic fluid and insulation material located between the outer cylindrical casings and the inner pipes; transporting said piping sections from the first location to a second location and assembling the piping sections into the vacuum insulated piping run by joining the ends of the inner pipes and then connecting shell-like sections to the outer cylindrical casings at junctures of the inner pipes; helium leak testing the junctures of the inner pipes and the connections of the shell-like sections such that at least a helium leak test is performed to determine the integrity of at least each of the junctures after forming each of the junctures and at least each of the connections is helium leak tested by temporarily sealing an inner annular region located between the outer cylindrical casings and the inner pipes and containing the insulation materials, evacuating the inner annular region through at least one opening formed in at least one of the outer cylindrical casings such that a plurality of the junctures and connections can be helium leak tested with the use of the at least one opening, introducing a helium tracer gas to each of the connections to be helium leak tested and testing an outlet stream evacuated through the at least one opening for presence of the helium tracer gas; after the vacuum insulated piping run is assembled, introducing a condensable gas into the vacuum insulated piping run, within the inner annular region, through the at least one opening; and subjecting the inner annular region to a subatmospheric pressure through the at least one opening and then sealing the at least one opening.