Pipe joints or couplings – Packed – Flanged pipe
Reexamination Certificate
1998-10-19
2001-07-31
Luu, Teri Pham (Department: 3627)
Pipe joints or couplings
Packed
Flanged pipe
C285S920000, C285S406000
Reexamination Certificate
active
06267419
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a remotely actuated and locked hub clamping connector particularly useful in subsea applications for attaching subsea Christmas trees to marine wellheads.
Wellheads are typically used in oil and gas production wells, injection wells, and storage wells, and in geothermal wells which produce steam for power generation. Wellheads are generally affixed to the casing or tubing strings of a well to enable production. In subsea applications, marine wellheads provide the control mechanism between the well and the surface equipment. To control the flow of the well, subsea Christmas trees, also called flow assembly devices, are attached to the wellhead. These subsea Christmas trees consist of a series of valves and fittings which enable the flow of the well to be controlled and enable the well to be externally shut-in if needed.
Generally speaking, several clamping connectors have been developed for attaching drilling and piping components to wellheads. For example, the FastLock™, the FlangeLock™, and the FastClamp™ Connector's illustrated and discussed on page 404 of the 1996-1997 Cameron Catalog of Oil Field Equipment, represent three such clamping connectors. Each of these three connectors is intended to replace flanged connectors and reduce the amount of time necessary for makeup. In each of the above designs, the wellhead is clamped to the drilling or piping component by applying a torque to a series of studs and nuts. These correctors are typically used onshore, as the necessity of requiring a torque to a series of studs and nuts makes these connectors impractical for use in subsea applications.
An additional onshore clamping connector is disclosed in prior art reference U.S. Pat. No. 4,883.293 (Lawson). Unlike the above three connectors, the Lawson connector achieves its clamping force by pre-stressing a series of tension members. The tension members are stretched, or preloaded or pre-stressed, by the application of hydraulic force. While in this preloaded state, a block is placed in the gap created by the stretched members which prohibits relaxation of the tension members. The attempt by the tension members to return to their relaxed, unloaded state creates a clamping force that continues until the blocks are removed and the tension members are able to return to their relaxed state. The necessity of placing the block in the gap created by the stretched members makes the connector impractical for use in subsea applications.
When dealing with subsea applications, it becomes necessary to simplify or eliminate totally the diver's tasks in locking the connector in order to secure the connection between the drilling or piping components and the wellhead. For that purpose, hydraulically actuated collet connectors such as are shown in U.S. Pat. No. 4,730,853 (Gjessing) have been developed and utilized. These collet-type connectors are designed for high pressure and deepwater drilling operations. The collet connectors are secured over the mating sections of the drilling or piping components to be connected by use of hydraulic pressure. Because the hydraulic pressure can be controlled remotely, it is not necessary for the divers to lock the collet connector in order to secure the connection.
Although effective, these prior subsea, hydraulically controlled connectors have the disadvantage of being tall, bulky, and thus, expensive. For example, the connector disclosed in U.S. Pat. No. 4,730,853 (Gjessing) must be tall enough to house the vertical locking components. The height of that connector is therefore dependent on the amount of clamping force desired: the greater the required clamping force desired, the taller the piston. In turn, the hub of the components to be connected must be at least as tall as the connector's housing. Consequently, if that connector is used to attach a subsea Christmas tree to a marine wellhead, the lower hub of the Christmas tree must extend upwardly from the wellhead to at least the top of the connector housing. The net effect is that the overall height of the subsea Christmas tree is increased. The increased height becomes extremely significant when discussing deepwater, subsea connections. Any increased height increases the length of the moment arm that is acted upon. Thus, with increased height, the connector is subjected to increased forces and moments and the connector consequently has decreased reliability and durability.
SUMMARY OF THE INVENTION
The present invention provides a new and improved clamping connector that is used in both subsea and surface applications. The present invention can be powered by mechanical means, or can utilize hydraulic or electric power so that the connector is remotely controlled if necessary. Although not limited to subsea applications, the use of remotely controlled power enables the connector of the present invention to be used in deepsea applications such as for attaching subsea Christmas trees to marine wellheads.
The present connector utilizes two clamp halves and a locking stem affixed to one clamp half and movable relative to the second clamp half from a first relaxed position to a second, pre-stressed position. The clamp halves are forced together and the locking stem is stretched, or preloaded or pre-stressed, by the application of forces generated by a power source (i.e., mechanical force, electric power, hydraulic pressure, etc.). While the locking stem is in this preloaded state, the power source is used to wedge a locking collet between the locking stem and the locking stem's exterior housing. When wedged between the locking stem and the housing, the locking collet resists the return of the stem from the second, pre-stressed position to its first, relaxed position even after the forces generated by the power source are relieved. The continued pre-stress on the locking stem provides the clamping force which enables the clamping connector to secure the connection. In the preferred embodiment, the locking stem is positioned in a bore in at least one of the clamp halves and the stem is locked in the pre-stressed position by a combination of the compressive clamping force, resulting from the wedging of the locking collet between the angled exterior surface of the locking stem and the angled interior surface of the clamp half, and the frictional engagement of the locking collet by the aforementioned angled surfaces.
It is, therefore, an object of the present invention to provide a new and improved clamping connector to overcome the above mentioned problems which limit the utility of prior connectors.
It is also an object of the present invention to provide a clamping connector which can utilize a power source such as hydraulic pressure to both open and close the connector. Because power sources such as hydraulic pressure can be controlled remotely, the connector is suitable for, but not limited to, subsea applications.
It is also an object of the present invention to decrease the overall height of the clamping connector that is necessary to provide a secure connection. (It should be noted that the term “height” as it is used in the present application simply refers to the dimension of the components along the plane perpendicular to the longitudinal axis of the locking stem). As discussed above, prior remotely controlled connectors have been limited by the height necessary to house all of the internal components. The present invention utilizes a unique and streamlined housing of its locking components. The locking stem and its housing are aligned perpendicular to the interior clamping surfaces. Thus, the only limitation on the overall height of the clamping connector of the present invention is that the connector must have sufficient height to provide sufficient surface area to enable the clamp halves to engage the hubs of the components to be clamped.
It is also an object of the present invention to provide a clamping connector that can be used subsea which has reduced overall height, and as a consequence, reduced overall weight and co
Baker Gerald S.
Taylor William M.
Cooper Cameron Corporation
Hartmann Michael P.
Luu Teri Pham
LandOfFree
Remotely actuated and locked hub clamp does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Remotely actuated and locked hub clamp, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Remotely actuated and locked hub clamp will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2468613