Claims
- 1. A transit capsule for transporting personnel in an atmospheric pressure air environment down to a sea-bed capsule enclosing an installation part and remaining in use full of water, said transit capsule having means for co-operating with complementary means on the sea-bed capsule to form a sealed conjunction through which access can be gained from the transit capsule to the sea-bed capsule, the improvements residing in the provision in the transit capsule of an expansion vessel for receiving that small part of the virtually incompressible water in the conjunction and sea-bed capsules which corresponds to the difference in the amounts of water held thereby at a pressure corresponding to the hydrostatic head of the sea depth and at atmospheric pressure, of means for selectively connecting the expansion vessel to the conjunction and sea-bed capsules for the passage of the said small part into the expansion chamber and allowing the pressures in all three capsules to equal each other and the atmospheric pressure in the transit capsule, and of means for inspecting said small part.
- 2. A transit capsule according to claim 1 wherein the inspecting means senses the amounts of said small part.
- 3. A transit capsule according to claim 2 wherein the inspecting means comprises a pressure guage for sensing the pressure rise in the expansion vessel and thus the amount of the said small part.
- 4. A transit capsule according to claim 1 wherein the inspecting means comprises means for detecting the nature of the said small part.
- 5. A transit capsule according to claim 4 wherein the said detecting means comprises a sight glass.
- 6. A transit capsule according to claim 4 wherein the detecting means comprises analytical apparatus.
- 7. A transit capsule according to claim 1 having a pump, a sea water inlet, and means for directing a purging flow of sea water from the inlet through the pump into the installation part capsule from which it leaves through a pressure relief valve or to an outlet in the transit capsule, whereby the purging flow can be kept at a mean pressure corresponding to that of the external sea whilst requiring a minimal head to create the purging flow.
- 8. A transit capsule according to claim 1 provided with shallow water diving support means whereby personnel from the transit capsule can enter the installation part capsule whilst it is full of water but at reduced pressure simulating shallow water irrespective of the depth of the installation capsule in the sea.
Parent Case Info
This application is a division of Application Ser. No. 685,676 filed May 12, 1976 which in turn is a division of Application Ser. No. 456,769, filed Apr. 1, 1974, now U.S. Pat. No. 3,968,656. The present invention concerns transit capsules for gaining operator access to a sealed capsule containing part of a sub-sea installation.
A transit capsule has means for co-operating with complementary means on the sea-bed to form a sealed conjunction capsule which encloses, or permits access to a further capsule enclosing, an installation part. The present invention concerns a transit capsule for use when there is a said further capsule. In the prior art, the conjunction capsule is pumped dry to allow access to the installation part therein or access to the sealed installation part further capsule which is left filled with gas at atmospheric pressure between socalled interventions. U.S. Pat. Application No. 685,676 however proposes that the installation part capsule is left filled with water which between interventions at or near external sea pressure but during interventions is reduced to atmospheric pressure; the conjunction capsule remaining water-filled as well and also being reduced in pressure during interventions. Unlike the prior art, the contents of the conjunction and installation part capsules remain unchanged except in pressure. There is thus a risk that leakage from the installation part of, say, oil will contaminate the working environment.
Accordingly the present invention provides a transit capsule having means for co-operating with complementary means on a sea-bed capsule sealingly enclosing an installation part on which a function is to be performed, which sea-bed capsule is intended to be full of water initially at or near pressure of the surrounding sea, to form a sealed conjunction capsule through which access can be obtained to the sea-bed capsule, characterised by the provision of an expansion vessel, means for selectively connecting the expansion vessel to the conjunction capsule and to the installation part capsule whereby the pressures in the conjunction capsule and the installation part capsule will be reduced by the expulsion of a small part of their substantially incompressible contents into the expansion vessel, and means for inspecting the said small part.
The inspecting means can inspect said small part quantatively and/or qualitatively. The quantity of the the said small part from the conjunction capsule will indicate the integrity of the conjunction capsule and the small amount from the installation part capsule will indicate the integrity of the installation part capsule and any gas leakage into the installation part capsule and any gas leakage into the installation part capsule from the installation part. Qualitative inspection of the small amount from the installation part capsule will show any oil leakage into the installation part capsule. Having determined that there is leakage, the leak would be stopped by operating valves which would be associated with the installation part and the contamination would be flushed out. Minimal energy would be required for flushing out since the installation part capsule would be sealed off and restored to sea pressure with the result that a flushing flow of sea water from the external sea whilst at high absolute pressure needs only a small pressure head.
An embodiment of the invention will now be described, by way of example with reference to the accompanying drawings.
US Referenced Citations (2)
| Number |
Name |
Date |
Kind |
|
1929168 |
Grieshaber |
Oct 1933 |
|
|
3855806 |
Therisien |
Dec 1976 |
|
Divisions (2)
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Number |
Date |
Country |
| Parent |
685676 |
May 1976 |
|
| Parent |
456769 |
Apr 1974 |
|
Patent Grant
4090366
