MXPA00006318A - Emergency dump apparatus for buoyancy air tanks on buoyant riser systems - Google Patents

Abstract

An apparatus for rapid venting of the compressed air and deballasting of a buoyant air tank in a positively buoyant riser system in the event of a premature drive off or a riser section parting is shown. The rapid venting of the compressed air ensures that the riser section cannot rapidly ascend to the surface and damage the drilling rig positioned above. In a first embodiment, the buoyancy tank or housing includes a vertical channel positioned on its exterior. A cover plate is placed over the vertical channel and sealed in place by a frangible weld. A tether line attaches to the cover plate and extends to an anchor point on the BOP stack below. In the event of a catastrophic parting of the riser, as the riser sections and attached buoyancy tank or housings begin ascending, the tether line is drawn tight. Further ascension of the buoyancy tank or housings, causes the frangible weld joints to break and peel back the cover plate, exposing the vertical channels. This causes an immediate and complete venting of the buoyancy tank or housings, rendering them negatively buoyant. Alternate embodiments are also shown

Description

EMERGENCY DRAINAGE APPARATUS FOR AIR FLOTATION TANKS IN BOYLIFT ELEVATOR SYSTEMS BACKGROUND OF THE INVENTION 1. FIELD OF THE INVENTION This invention relates to a novel apparatus for rapidly releasing air from flotation tanks or housings in those situations where rapid deslastration of tanks or flotation housings is required. A typical situation where this could happen is the case of a free-set drill lift that replaces most of the positive flotation drill rig tension provided by the tanks or flotation housings mounted on the riser sections. In the event of a catastrophic failure of the lift, that is, where the lift under the tanks or flotation housings has separated or a lower part releases in an apartment of the dynamically placed vessel, the sections of the buoyantly positive elevator with tanks or housings of fixed flotation would rise to the surface with increased velocity to impact the equipment's hull or drill vessel with sufficient force to seriously damage the rig. In the extreme case, the impact of the elevator and the flotation tank or flotation housing can sufficiently damage the rig or the drilling vessel to make it sink and lives can be lost. The use of these positively buoyant elevators with tanks or flotation housings provide flotation that is well known to those of ordinary skill in the art. Typical use dictates several elevator sections that will have fixed flotation tanks or housings, depending on the depth of the water, to leave the elevator disconnected and free of attachment or at least minimize the load on the tower tensioner system. piercing while connecting. The flotation tanks or housings are usually constructed with an open lower end to facilitate the filling of the flotation tanks or housings by compressed air or other suitable gas. The volume and pressure of the compressed air supplied are determined by the depth of water in which the tanks or flotation housings are going to be used. The different methods of filling the tanks or flotation housings either individually or in the group are well known to those of ordinary skill in the art. Once the sections of the elevator with the fixed flotation tanks or housings are in place, the present invention has particular applicability. In the event that the elevator should fall as noted above, a particularly dangerous situation occurs due to positively buoyant tanks or housing. The present invention minimizes this dangerous situation by allowing a means to deflate or strip the flotation tank or housing in a few seconds. This rapid release or deslastration of these flotation tanks or housings to which the present invention extends more closely. 2. Description of the Related Art A marine elevator with open lower air canisters is shown in U.S. Patent No. 4,099,560 (Fischer et al.). The device shown by Fischer et al. Discloses an air dump valve attached to a line of maneuver that is activated in the event of elevator separation. U.S. Patent No. 4,176,986 to Taft et al. Discloses another type of lift system with attached flotation tanks. A drain valve is shown to rapidly vent the compressed air and controlled by a pilot valve assembly.

Another marine elevator with flotation system is disclosed in U.S. Patent No. 4,422,801 (Hale et al.). The system shown by Hale et al. Uses a quarter-turn ball valve operated by a trigger cable and an air cylinder to vent the air flotation tanks. United States Patent No. 4, 646,840 to Bartholomew et al., Appropriated by the assignee of the present invention, discloses a tank or housing flotation system with a cascade system for supplying air to the flotation tank or housing. All of these systems are too slow for a dynamically placed vessel that must vent in less than thirty seconds to avoid damage to the drilling vessel.

BRIEF DESCRIPTION OF THE INVENTION The present invention utilizes a frangible connection or connection to allow rapid venting of compressed air and the debulking of a flotation tank or housing in a positively buoyant lifting system in the event of a separation of the elevator section. Rapid venting of compressed air ensures that the lift section can not rise rapidly to the surface and damage the drilling equipment placed on top. According to the present invention, in a first embodiment the flotation tank or housing includes a vertical channel placed on its exterior. A cover plate is placed over the vertical channel and sealed in place by a frangible weld. The cover plate includes a radially outwardly extending arm to which a line of maneuver is secured. The line of maneuver extends downward to the arms similarly placed on the rear riser sections and to the associated float tanks or housings. The maneuvering line extends from all or the selected flotation tanks to the lowermost float tank or housing and is secured over the BOP stack below. The maneuvering lines can extend downwards from the individual flotation tanks or housings or from a series of tanks or flotation housings. In the event of a catastrophic separation of the elevator, as the elevator sections and the attached flotation tanks or housings are ascending, the line of maneuver is pulled tense. The additional ascension of the flotation tanks or housings causes the frangible welding joints to break and separate from the cover plate, exposing the vertical channels. These cause an immediate and complete venting of the air in the tanks or flotation housings, making them buoyant in a negative way. In a second embodiment of the invention, the flotation tank or housing includes a circumferentially formed channel placed on its upper face. An annularly formed cover plate is placed on the circumferentially formed channel and sealed in place by a frangible weld. The annularly formed cover plate includes a ring placed on its bottom face to which the locking line is secured. The locking line extends down to the similarly placed rings on the rear elevator sections and the flotation tanks or housings. The locking line extends from the lowermost float tank or housing and is secured to the lower BOP stack. In the event of a catastrophic elevator separation, as the sections of the elevator and the attached flotation tanks or housings are ascending, the locking line is dragged in a tense manner. The additional ascension of the flotation tanks or housings, causes the unions of the frangible welding to break and separate from the cover plate, exposing the circumferentially formed channels. This causes an immediate and complete release of the flotation tanks or housings, making them buoyant in a negative way.

In a third embodiment of the invention, the flotation tank or housing includes an annularly formed flange positioned on top. The annularly formed flange has a solder joint on its interior and a seal on its exterior for sealing against the sections of the elevator and the flotation tank or housing, respectively. The flange is retained by a plurality of hinged connection retainer clips. The articulated connection retainer clips are connected to a locking line extending from the lowermost float tank or housing and secured to the BOP stack below. In the event of a catastrophic separation of the elevator, the separation of the elevator causes the locking line to release the frangible retaining pins that retain the articulated connection retainer clips thereby releasing the annularly formed flange of the flotation housing. This causes an immediate and complete release of the tanks or flotation accommodations, making them buoyant in a negative way. In a fourth embodiment of the invention, the flotation tank or housing includes an annularly formed flange placed on top. The annularly formed flange has a solder joint on its interior and a seal on its exterior for sealing against the sections of the elevator and the flotation tank or housing, respectively. The flange is retained by a plurality of retaining pin assemblies. The retaining pin assemblies are connected to a locking line extending from the lowermost float tank or housing and secured to the BOP stack below. In the event of a catastrophic separation of the elevator, the separation of the elevator causes the locking line to release the removable retaining pins thus releasing the annularly formed flange of the flotation tank or housing. This causes an immediate and complete release of the flotation tanks or housings, making them buoyant in a negative way.

In a fifth embodiment of the invention, the flotation tank or housing includes an annularly formed flange placed on top. The annularly formed flange has a solder joint on its interior and a seal on its exterior for sealing against the sections of the elevator and the flotation tank or housing, respectively. The flange is retained by a plurality of detonating or explosive bolt assemblies. The explosive bolt assemblies are connected to a transceiver box connected to the explosive bolt assemblies. In the event of a catastrophic separation of the elevator, a signal is transmitted to the transceiver box which in turn activates the explosive bolt assemblies. The release of the explosive bolt assemblies allows the annularly formed flange to be released from the flotation tank or housing. This causes an immediate and complete release of the flotation tanks or housings, making them buoyant in a negative way. A principal object of the present invention is to provide an apparatus for rapidly venting the air from the flotation tanks or housings thus preventing the uncontrolled and rapid ascent to the surface. Another object of the present invention is to provide an apparatus for rapidly venting the air from the flotation tanks or housings without requiring any intervention of the operator in the success of the elevator parts. These with other objects and advantages of the present invention are pointed out with specification in the appended claims to this and form a part of this disclosure.

A complete and complete understanding of the invention can be taken with reference to the accompanying drawings and description of the preferred embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS These and other objects and advantages of the present invention are set forth below and are made clearer with reference to the drawings, wherein: Figure 1 is an elevational view of an elevator system with the tank or housing floatation used in subsea oil and gas drilling operations incorporating the emergency casting apparatus of the present invention. Figures 2 and 2A are isometric views of the first embodiment of the emergency emptying apparatus before being activated. Figures 3 and 3A are sectional views showing details of the first embodiment of the emergency emptying apparatus before being activated. Figure 4 is a sectional view of the first embodiment of the emergency emptying apparatus after activation. Figure 5 is an isometric view of the second embodiment of the emergency emptying apparatus before being activated. Figure 6 is an isometric view of the second embodiment of the emergency emptying apparatus after activation. Figure 7 is a sectional view of the third embodiment of the emergency emptying apparatus before being activated. Figure 8 is a sectional view of the third embodiment of the emergency emptying apparatus after activation. Figure 9 is a sectional view of the fourth embodiment of the emergency emptying apparatus before being activated. Figure 10 is a sectional view of the fourth embodiment of the emergency emptying apparatus after activation. Figure 11 is a sectional view of the fifth embodiment of the emergency emptying apparatus before being activated.

Figure 12 is a sectional view of the fifth embodiment of the emergency emptying apparatus after activation.

DESCRIPTION OF CURRENTLY PREFERRED MODALITIES With reference to the drawings, and particularly to Figure 1, the subsea drilling elevator system 100 is shown in an elevation view. The underwater drilling elevator system 100 extends from the floating drilling rig 102 to the BOP 104 tower located at the bottom of the ocean 106. The underwater drilling rig 100 is comprised of a plurality of elevator sections 108 connected in a end-to-end relationship by mechanical means suitable as end connections 110 which may be threaded connections, flanged end connections or clamp hub connections as is well known to those of ordinary skill in the art. Some of the sections of the elevator 108 have tanks or flotation housings 112 secured therein or these can be formed integrally therewith without departing from the spirit of the invention. The flotation housing tank or housing 112 is filled with compressed air to provide flotation to the subsea drilling elevator system 100 by alleviating or obviating the need for an elevator tensioning system. The upper connector of the elevator 114 is provided near the upper end of the lifting system 100 to allow the drilling equipment 102 to disconnect from the lifting system 100 in the event of separation or stormy weather that needs the suspension of the drilling operations. The locking line 116, of suitable material such as chain, wire or polyester rope, extends from the flotation tank or housing 112 to the BOP tower 104 under the lower marine elevator package where it is secured for the purposes that will be explained here below. . As best seen in Figures 2 and 2A, the first embodiment of the present invention includes a float tank or housing 112 attached to the elevator section 108. The float tank or housing 112 includes a frangible section 118 to which it is attached. the actuating arm 120 is fixed. The locking line 116 is connected to the actuating arm 120 and extends down to the BOP tower 104 as noted above. The frangible section 118 includes the vertical channel 122 in the float tank or housing 112 which is sealed by the cover plate 124. With reference to Figures 3 and 3A, the cover plate 124 is sealed by the frangible weld seal 126. The cover plate 124 extends vertically along the flotation tank or housing 112 and is completely sealed around its periphery by the frangible welded seam 126. The frangible welded seal 126 is sized to break when a suitable predetermined force is applied by the locking line 116 acting on the actuating arm 120. In the event of a catastrophic elevator failure, that is, when the elevator below the air tanks has separated, the positively buoyant elevator sections 108 with the tank or United accommodations 112 will ascend to the surface with increased speed unless the air is immediately exhausted. Within the tank or flotation housing 112. As the positively buoyant elevator sections 108 with the attached flotation tank or housing 112 begin to ascend toward the surface, the locking line 116 is pulled tightly and begins to pull on the actuation arm 120. As best seen in Figure 4, the continuous rise of the elevator sections 108 with the attached float tank or housings 112 causes the frangible welded joint 126 to break and separate the deck plate 124 from the tank or floatation housing 112. This unraveling of cover plate 124 leaves vertical channel 122 open to sea water and thereby de-igniting the compressed air from floatation tank or housing 112 and rendering the elevator sections 108 buoyant in a negative manner . The sections of the separate elevator 108 with the air tanks 112 attached then hang over the tensioners of the rig or in the worst circumstances will fall back toward the seabed where they can be retrieved later. The drilling equipment 102 is thus protected from being "torpedoed" by the elevator sections 108. A second embodiment of the present invention is shown in Figures 5 and 6. Those items that are the same as in the first embodiment retain the same numerical designation. As in the first modality, an elevator section 108 has the float tank or housing 210 secured thereto. The float tank or housing 210 includes the frangible section 112 to which the actuation ring 214 is attached. The lock line 116 is connected to the actuation ring 214 and extends downwardly to the BOP tower as noted above. The frangible section 212 includes a circumferentially formed channel 216 in the flotation tank or housing 210 which is sealed by the annularly formed ring 218. The annularly formed ring 218 is sealed by the frangible welded joint 220. The annularly formed ring 218 extends circumferentially around the float tank or housing 210 and is completely sealed around its periphery by the frangible welded joint 220. The frangible welded joint 220 is sized to break when a suitable predetermined force is applied by the locking line 116. The restricting line 222 extends between the float tank or housing 210 and the elevator section 108 and connects the the restrictive collars 224 that are welded to the float tank 210 and the elevator section 108. As in the first embodiment, when a catastrophic elevator failure occurs, the ascent of the positively buoyant elevator sections 108 with the float tank or housing 210 causes the locking line 116 to be dragged tautly start and pull on the actuation ring 214. As best seen in Figure 6, the continuous ascent of the elevator sections 108 with the float tank or housing 210 causes the frangible welded joint 220 to break and separating the annularly formed ring 218 from the flotation tank or housing 210. This disengagement from the annularly formed ring 218 leaves the circumferentially formed channel open to the seawater and thereby depresses the compressed air from the flotation tank or housing 210 and makes the the buoyant elevator sections in a negative way. The restricting line 222 ensures that the float tank or housing 210 does not completely separate from the elevator section 108 and thus aids in the recovery operations. A third embodiment of the present invention is shown in Figures 7 and 8. Those items that are the same as in the first embodiment retain the same numerical designation. As in the first embodiment, the elevator section 108 has the flotation tank or housing 310 attached thereto. The flotation tank or housing 310 has the articulated connection fastening assembly 312 positioned at its upper end to which the actuation arm 314 is fixed. The locking line 116 is connected to the actuation arm 314 and extends down to the BOP tower 104 as previously noted. The hinged connection fastener assembly 312 retains the hinged connection retaining clamps 322 in engagement by retaining the annularly formed flange 316 sealing within the upper portion of the float tank or housing 310 with an annular seal ring 320. The flange is annularly formed 316 is fixed and sealed against the section of the riser 108 by the welds 318. The annularly formed flange 316 is retained by the sealing coupling with the float tank or housing 310 by the hinged connection retaining brackets 322. The retaining clips of FIG. articulated connection 322 include a frangible retaining pin 324. The frangible retaining pin 324 is sized to break when a suitable predetermined force is applied by the locking line 116. The restricting line 326 extends between the float tank or housing 310 and the section of the elevator 108 and connect to the co restraining lugs 328 that are welded to the flotation tank 310 and the elevator section 108. As in the above embodiments when the catastrophic failure of the elevator occurs the ascent of the positively buoyant elevator sections 108 with the float tank or housing 310 attached causes that the locking line 116 is pulled taut and begins to pull on the actuation arm 314. As best seen in Figure 8, the continuous rise of the sections of the elevator 108 with the fixed flotation tank or housing 310 originates that the frangible retainer pin 324 and the articulated connection retaining clips 322 release the annularly formed flange 316 of the flotation tank or housing 310. This disengagement of the annularly formed flange 316 allows the flotation tank or housing 310 to vent the compressed air thereof and cause the elevator sections 108 buoyant in a negative manner. The restricting line 326 ensures that the flotation tank or housing 310 does not completely separate from the elevator section 108 and thus aids in the recovery operations. A fourth embodiment of the present invention is shown in Figures 9 and 10. Those items that are the same as in the first embodiment retain the same numerical designation. As in the first modality, the elevator section 108 has a float tank or housing 410 attached thereto. The flotation tank or housing 410 has a retainer pin assembly 412 positioned at its upper end to which the actuating arm 414 is fixed. The locking line 116 is connected to the actuating arm 414 and extends down to the BOP tower 104. as noted above. The retainer pin assembly 412 retains the retainer arm 416 in engagement retaining the annularly formed flange 418 which seals within the upper portion of the float tank or housing 410 with an annular seal ring 420. The annularly formed flange 418 is attached and sealed against the section of the riser 108 by the welds 422. The annularly formed flange 418 is retained by the seal coupling with the float tank or housing 410 by the retainer arm 416. The retainer arm 416 is held in place by the assembly of retainer pin 412 including removable retainer pin 424. Removable retainer pin 424 is released when an appropriate predetermined force is applied by locking line 116 to actuating arm 414 and pivots retainer pin assembly 412 outwardly. The restricting line 426 extends between the float tank or housing 410 and the elevator section 108 and connects the restrictive collars 428 that are welded to the float tank 410 and the elevator section 108. As in the above embodiments when a failure occurs. catastrophic of the elevator the rise of the positively buoyant elevator sections 108 with the attached float tank or housing 410 cause the locking line 116 to be dragged tensely and begin to pull on the actuating arm 414. As best seen in Figure 10, the continuous rise of the sections of the riser 108 with the attached float tank or housings 410 causes the retainer pin assembly 412 to pivot outward and remove the retainer pin 424 from the retainer arm 416 to release the annularly formed flange 418 of the float tank or housing 410. This disengagement of the annularly formed flange 418 allows the float tank 410 accommodates the compressed air thereof and causes the elevator sections 108 to be buoyant in a negative manner. Restrictor line 426 ensures that the float tank or housing 410 does not completely separate from the elevator section 108 and thus aids in recovery operations. A fifth embodiment of the present invention is shown in Figures 11 and 12. Those items that are the same as in the first embodiment retain the same numerical designation. As in the first embodiment, the elevator section 108 has the float tank or housing 510 secured thereto. The flotation tank or housing 510 has an explosive bolt assembly 512 positioned at its upper end. A sensor means such as the transceiver box 514 is attached to the float tank or housing adjacent to the explosive bolt assembly 512. The connection of the control 516 connects the transceiver box 514 to a remote release means such as an explosive bolt assembly 512. The explosive bolt assembly 512 retains the annularly formed flange 518 which seals within the upper part of the flotation tank or housing 510 with an annular seal ring 520. The annularly formed flange 518 is fixed and sealed against the elevator section 108. by the welds 522. The annularly formed flange 518 is retained in seal engagement with the flotation tank or housing 510 by the explosive bolt assembly 512. The explosive bolt assembly 512 is activated when the detection of a lift separation occurs. a signal or a detector means is sent such as the transceiver box 514. Said signal can be mechanical, electrical, acoustic or hydraulic, without departing from the scope of the present invention. Restrictor line 524 extends between the flotation tank or housing 510 and the elevator section 108 and connects the restrictive collars 526 that are welded to the float tank 510 and the elevator section 108. When a catastrophic failure of the elevator occurs it is transmitted a signal to the transceiver box 514 which in turn activates the explosive bolt assembly 512 through the conductor 516. As best seen in Figure 10, the release of the explosive bolt assembly 512 allows the annularly formed flange 510 to be released from the flotation tank or housing 510. This disengagement from the annularly formed flange 518 allows the flotation tank or flotation housing 510 to vent into the compressed air thereof and causes the elevator sections 108 to buoyantly negative. Restrictor line 524 ensures that the float tank 510 does not completely separate from the riser section 108 and thus aids in recovery operations. My improved apparatus for providing rapid venting of the compressed and delastered air from a buoyant air tank in a positively buoyant riser system in the event of the separation of a section of the elevator and the methods of its application, will be easily understood from the previous description.

Furthermore, although the invention has been shown and described with respect to certain preferred embodiments, it is obvious that alterations and modifications equivalent to those skilled in the art will occur when reading and understanding the description. The present invention includes all equivalent alterations and modifications, and is limited only by the scope of the appended claims.

Claims (17)

1. An apparatus for emergency emptying for tanks or flotation housings in buoyant elevator systems in an underwater environment, comprising: a flotation housing positioned around a section of the elevator, said flotation housing including a frangible section; a detection means; a remote release means placed in said frangible section of said flotation housing and controlled by said detection means, said detection means activating the release means upon separation of the elevator to disengage the frangible section of said flotation housing and flooding said float housing.

2. An apparatus for emergency emptying for floating tank or housings used in buoyant elevator systems in an underwater environment in accordance with claim 1, wherein said frangible section of the flotation housing includes an annular flange which seals the ring between the section of the riser and float housing to maintain pressure within the float housing prior to separation of the frangible section.

3. An apparatus for emergency emptying for flotation tanks or housings used in buoyant elevator systems in an underwater environment in accordance with claim 2, wherein the detection means responds to a separation of the elevator.

4. An apparatus for emergency emptying for flotation tank or housings used in buoyant elevator systems in an underwater environment in accordance with claim 3, wherein said release means is an explosive bolt assembly.

5. An apparatus for emergency emptying for flotation tank or housings used in buoyant elevator systems in an underwater environment, comprising: a flotation housing positioned around a section of the elevator, said flotation housing including a frangible section; said frangible section of the float housing connected to a locking line whereby a separation of the elevator causes the locking line to separate the frangible section from the float housing and flood the float housing.

6. An apparatus for emergency emptying of flotation tanks or housings used in buoyant elevator systems in an underwater environment in accordance with claim 5, wherein the frangible section of the flotation housing includes a vertical channel in said flotation housing, said vertical channel sealed by a cover plate to maintain pressure within the float housing prior to separation of the frangible section.

7. An apparatus for emergency emptying for floatation tank or housings used in buoyant elevator systems in an underwater environment in accordance with claim 6, wherein the seal between the vertical channel and the cover plate is a frangible welded seal.

8. An apparatus for emergency emptying for floatation tank or housings used in buoyant elevator systems in an underwater environment in accordance with claim 5, wherein the frangible section of the float housing includes a circumferentially formed channel in said float housing, said circumferentially formed channel sealed to maintain the pressure within the flotation housing prior to separation of the frangible section.

9. An apparatus for emergency emptying for floating tank or housings used in buoyant elevator systems in an underwater environment in accordance with claim 8, wherein said channel circumferentially formed in said flotation housing is sealed by an annularly formed ring.

10. An apparatus for emergency emptying for floatation tank or housings used in buoyant elevator systems in an underwater environment in accordance with claim 9, wherein said seal between said circumferentially formed channel in said float housing and said cover plate is a frangible welded joint.

11. An apparatus for emergency emptying for floating tank or housings used in buoyant elevating systems in an underwater environment, comprising: a flotation housing positioned around a section of the elevator, said floating housing including a rapidly removable section; said rapidly removable section of the flotation housing connected to the locking line whereby a separation of the elevator causes the locking line to release said rapidly removable section from the flotation housing and flood said flotation housing.

12. An apparatus for emergency emptying for flotation tanks or housings used in buoyant elevator systems in an underwater environment in accordance with claim 11, wherein said rapidly removable section of the flotation housing is an annularly formed flange.

13. An apparatus for emergency emptying for floatation tank or housings used in buoyant elevator systems in an underwater environment in accordance with claim 12, wherein said annularly formed flange sealingly couples said float housing and said elevator section.

14. An apparatus for emergency emptying for flotation tank or housings used in buoyant elevator systems in an underwater environment in accordance with claim 13, wherein said annularly formed flange is retained in sealing engagement with said flotation housing and said elevator section by a plurality of hinged connection retainer clips.

15. An apparatus for emergency emptying for floating tank or housings used in buoyant elevator systems in an underwater environment in accordance with claim 14, wherein each of the articulated connection retainer clips includes a frangible retainer pin; and said plurality of articulated connection retainer fasteners are connected to a locking line whereby a separation of the elevator causes the locking line to release the frangible retaining pins and said plurality of articulated retaining fasteners thereby releasing the tabularly annularly formed from the float housing and floods said float housing.

16. An apparatus for emergency emptying for flotation tanks or housings used in buoyant elevator systems in an underwater environment in accordance with claim 13, wherein said annularly formed flange is retained in seal engagement with said flotation housing and said section of the elevator by a plurality of pin retainer assemblies.

17. An apparatus for emergency emptying for floating tank or housings used in buoyant elevator systems in an underwater environment in accordance with claim 16, wherein said plurality of pin retainer assemblies include a removable retainer pin; and said plurality of pin retainer assemblies are connected to a locking line whereby a separation of the elevator causes the locking line to release the retainer removable pins and thereby release said annularly formed flange of the flotation housing and flood said flotation housing. . SUMMARY An apparatus for the rapid venting of compressed air and the debulking of a buoyant air tank in a positively buoyant riser system in the event of a premature removal or separation of the elevator section is disclosed. The rapid release of compressed air ensures that the section of the lift can not rise quickly to the surface and damage the drilling equipment placed on top. In a first embodiment, the flotation tank or housing includes a vertical channel placed on its exterior. A cover plate is placed over the vertical channel and sealed in place by a frangible weld. A locking line joins the cover plate and extends to an anchor point on the BOP tower below. In the event of a catastrophic separation of the elevator, as the sections of the elevator and the tanks or floatation housings are ascending, the locking line is dragged in a tense manner. The additional ascent of the flotation tanks or housings causes the frangible welding seals to break apart the cover plate, exposing the vertical channels. This causes an immediate and complete venting of the air in the tanks or flotation housings, making them buoyant in a negative way. In a second embodiment of the invention, the flotation tank or housing includes a circumferentially formed channel positioned on its upper face with an annularly formed cover plate placed on the circumferentially formed channel and sealed in place by a frangible weld. A fixed locking line to the cover plate annularly formed as in the first embodiment. In a third embodiment of the invention, the flotation tank or housing includes an annularly formed flange positioned on top. The tab annularly formed seal to the tank or flotation housing. The flange is retained by a plurality of articulated connection retaining clamps. The articulated connection retaining clamps are connected to a locking line as in the previous modes. A fourth modality uses removable retaining bolts to retain the flange and these are released by the locking lines as in the previous modalities. A fifth embodiment uses an explosive bolt assembly activated by a remote sensing means to release the flange.