Method and apparatus for forming a temporary plug in a submarine conduit

Claim 7

The method set forth in claim 3 together with the step of: supplying pressure gas to purge said chamber from said source of low temperature fluid by vaporizing said fluid and pumping said fluid vapor to said chamber.

Claim 8

The method set forth in claim 3 together with the steps of: connecting second and third ones of said flexible conduits to third and fourth valves in communication with said chamber; and connecting the opposite end of one of said second and third conduits with said source of low temperature fluid and with a vent line, said vent line having an outlet above the water surface.

Claim 9

The method set forth in claim 5 together with the steps of: opening said one of said third and fourth valves and said vent line; and conducting low temperature fluid to said chamber and venting fluid vapor from said chamber to the atmosphere above the water surface through said vent line.

Claim 10

The method set forth in claim 6 together with the steps of: opening the other of said third and fourth valves and closing said one valve and said vent line; and conducting low temperature fluid in a liquid state from said source to said chamber and returning said liquid to said source.

Claim 11

The method set forth in claim 5 wherein: said method includes controlling the flow of low temperature fluid through said chamber to maintain the fluid pressure in said chamber at a predetermined value in relation to the water pressure in the vicinity of said housing.

Claim 12

The method set forth in claim 3 wherein: said method includes providing a first surface vessel including means for connecting said conduits to said source of low temperature fluid, said means including further conduits and connector means; providing a second surface vessel including said source of low temperature fluid on board; and anchoring said first surface vessel and connecting said flexible conduits to said source of low temperature fluid through said connector means on said first surface vessel and said further conduit means.

Claim 13

The method set forth in claim 3 together with the step of: monitoring the temperature on the surface of said pipeline within said chamber during the supplying of low temperature fluid to said chamber.

Claim 14

The method set forth in claim 1 or 9 together with the steps of: providing pump means and compressor means connected in parallel to said source of low temperature fluid; and controlling said pump means or said compressor means to supply low temperature fluid to said chamber at a predetermined pressure.

Claim 15

In an apparatus for forming a temporary plug in a submarine fluid transmission line by freezing a quantity of liquid at a predetermined location within said transmission line; a housing comprising at least two housing sections formed in such a way as to provide for removably mounting said housing around the exterior of said transmission line at said predetermined location to form a chamber around the exterior of said transmission line, first and second fluid conduits in communication with said chamber in said housing, first and second power operated valves connected to said first and second conduits, respectively, for controlling the flow of fluid through said conduits and said chamber, first connector means for releasably connecting said conduits to a source of low temperature fluid, said source comprising a reservoir, and a pump connected to said reservoir for conducting fluid to said chamber by way of said conduit, said housing including a third conduit in communication with said chamber and a third valve in said conduit for conducting water out of said chamber to purge said chamber after installation of said housing around said transmission line; an elongated conduit assembly including at least two separate supply and return conduits and second connector means for releasably connecting said reservoir to said chamber by way of said conduit assembly and said first and second connector means for circulating low temperature fluid through said chamber to freeze said liquid to form said plug; and means for supplying pressure gas through one of said first and second conduits to purge water out of said chamber by way of said third valve and said third conduit.

Claim 16

In an apparatus for forming a temporary plug in a submarine fluid transmission line by freezing a quantity of liquid at a predetermined location within said transmission line; a housing comprising at least two housing sections formed in such a way as to provide for removably mounting said housing around the exterior of said transmission line at said predetermined location to form a chamber around the exterior of said transmission line, first and second fluid conduits in communication with said chamber in said housing, first and second power operated valves connected to said first and second conduits, respectively, for controlling the flow of fluid through said conduits and said chamber, first connector means for releasably connecting said conduits to a source of low temperature fluid, said source comprising a reservoir, and a pump connected to said reservoir for conducting fluid to said chamber by way of said conduit, said housing including a third conduit in communication with said chamber and a third valve in said conduit for conducting water out of said chamber to purge said chamber after installation of said housing around said transmission line; an elongated conduit assembly including at least two separate supply and return conduits and second connector means for releasably connecting said reservoir to said chamber by way of said conduit assembly and said first and second connector means for circulating low temperature fluid through said chamber to freeze said liquid to form said plug; and means for supplying pressure gas through one of said first and second conduits to purge water out of said chamber by way of said third valve and said third conduit.

Claim 17

The apparatus set forth in claim 12 wherein: said third valve is normally closed and is power operated to be in an open position when said pressure gas is being conducted to said chamber.

Claim 18

The apparatus set forth in claim 12 wherein: said pressure gas is supplied from said source of low temperature fluid, said apparatus including a pressure gas supply circuit in communication with said reservoir, said circuit including a heat exchanger for heating said low temperature fluid to convert said fluid to a gaseous state, a compressor in said circuit for compressing said gas, and valve means for switching said compressor into communication with one of said first and second conduits for conducting pressure gas to said chamber.

Claim 19

The apparatus set forth in claim 14 wherein: said reservoir, said pump and said compressor are disposed on board a floating vessel and are interconnected to said conduit assembly by releasable connector means at a buoy anchored generally above said predetermined location on said transmission line.

Claim 20

The apparatus set forth in claim 15 together with: signal conductor means comprising signal conductors connected to said valves for operating said valves, an elongated signal conductor assembly including releasable connector means for connecting respective signal conductors leading to said valves to a control station on said vessel through a releasable connector assembly on said buoy.

Claim 21

The apparatus set forth in claim 12 wherein: said housing includes a fourth conduit in communication with said chamber and a vent conduit interconnected between said fourth conduit and a vent, a fourth valve interposed in said fourth conduit, said fourth valve being power operated to be opened to vent fluid vapor from said chamber when said low temperature fluid is being supplied to said chamber.

Claim 22

The apparatus set forth in claim 17 wherein: said vent includes a conduit in said conduit assembly for conducting fluid vapor to the surface of a body of water in which said transmission line and said housing are submerged.

Claim 23

The apparatus set forth in claim 17 wherein: said housing includes a pair of opposed semi-cylindrical shells removably connectable to each other to form said chamber around said transmission line, manifold means in each of said shells for distributing fluid to said chamber, said first and second conduits opening directly into said manifold, said fourth conduit opening directly into said chamber, and said third conduit opening into said chamber and said manifold.

Claim 24

The apparatus set forth in claim 19 wherein: said housing includes means for sensing the fluid pressure within said chamber.

Claim 25

The apparatus set forth in claim 17 wherein: said first, second and fourth conduits are disposed in said conduit assembly, said conduit assembly including releasable connectors at opposite ends thereof for connecting said housing to said source of low temperature fluid and said vent, respectively.

Claim 26

In an apparatus for forming a temporary plug in a submarine fluid transmission line by freezing a quantity of liquid at a predetermined location within said transmission line; a housing comprising at least two housing sections formed in such a way as to provide for removably mounting said housing around the exterior of said transmission line at said predetermined location to form a chamber around the exterior of said transmission line, first and second fluid conduits in communication with said chamber in said housing, first and second power operated valves connected to said first and second conduits, respectively, for controlling the flow of fluid through said conduits and said chamber, first connector means for releasably connecting said conduits to a source of low temperature fluid, said source comprising a reservoir, and a pump connected to said reservoir for conducting fluid to said chamber by way of said conduits; an elongated conduit assembly including at least two separate supply and return conduits and second connector means for releasably connecting said reservoir to said chamber by way of said conduit assembly and said first and second connector means for circulating low temperature fluid through said chamber to freeze said liquid to form said plug; and means for supplying pressure gas from said source of low temperature fluid for purging water out of said chamber including a pressure gas supply circuit in communication with said reservoir, said circuit including a heat exchanger for heating said low temperature fluid to convert said fluid to a gaseous state, a compressor in said circuit for compressing said gas, and valve means for switching said compressor into communication with one of said first and second conduits for conducting pressure gas to said chamber.

Claim 27

In an apparatus for forming a temporary plug in a submarine fluid transmission line by freezing a quantity of liquid at a predetermined location within said transmission line; a housing comprising at least two housing sections formed in such a way as to provide for removably mounting said housing around the exterior of said transmission line at said predetermined location to form a chamber around the exterior of said transmission line, first and second fluid conduits in communication with said chamber in said housing, first and second power operated valves connected to said first and second conduits, respectively, for controlling the flow of fluid through said conduits and said chamber, first connector means for releasably connecting said conduits to a source of low temperature fluid, said source comprising a reservoir, and a pump connected to said reservoir for conducting fluid to said chamber by way of said conduits; an elongated conduit assembly including at least two separate supply and return conduits and second connector means for releasably connecting said reservoir to said chamber by way of said conduit assembly and said first and second connector means for circulating low temperature fluid through said chamber to freeze said liquid to form said plug; and means for supplying pressure gas from said source of low temperature fluid for purging water out of said chamber including a pressure gas supply circuit in communication with said reservoir, said circuit including a heat exchanger for heating said low temperature fluid to convert said fluid to a gaseous state, a compressor in said circuit for compressing said gas, and valve means for switching said compressor into communication with one of said first and second conduits for conducting pressure gas to said chamber.

Claim 28

The apparatus set forth in claim 22 wherein: said reservoir, said pump and said compressor are disposed on board a floating vessel and are interconnected to said conduit assembly by releasable connector means at a buoy anchored generally above said predetermined location.

Claim 29

The apparatus set forth in claim 23 together with: signal conductor means comprising signal conductors connected to said valves for operating said valves, and an elongated signal conductor assembly including releasable connector means for connecting respective signal conductors leading to said valves to a control station on said vessel through a releasable connector assembly on said buoy.