Pipe joints or couplings – With means blocking release of holding means – Set screw
Reexamination Certificate
1999-06-28
2001-12-11
Luu, Teri Pham (Department: 3627)
Pipe joints or couplings
With means blocking release of holding means
Set screw
C285S123900, C285S123130, C285S404000
Reexamination Certificate
active
06328343
ABSTRACT:
PRIOR ART
In marine riser pipe systems for use in drilling underwater well bores, pipe joints are coupled to one another by connector members. A connection is made between a pin portion of a length of pipe and a box portion of a second length of pipe. The box portion of one member is adapted to telescopically fit on the pin portion of an adjacent joint. To lock the box and pin members together to prevent axial separation, dogs may be used to engage a groove in the pin.
A typical actuator device comprises a housing welded to the box member wherein the housing includes a threaded bore. A threaded actuator screw is located in the threaded bore. The threaded actuator screw has an annular enlargement or flange on its inner end rotatably disposed in a slot of an actuator pad or dog. The actuator pad is disposed in a radial opening in the box member and has an inner face curved to conform generally to the outer periphery of the grooves on the pin. At its outer end, the actuator screw has a non-circular or hexagonal head adapted to be engaged by a driving tool or wrench so that the pad may be shifted inwardly into locking engagement in the groove of the pin member, or the pad may be shifted outwardly to allow removal of the box member from the pin member.
A difficulty encountered with the traditional actuator device is that of disengaging a defective actuator screw. If the actuator screw is prevented from being removed from the actuator housing by galling of the actuator screw threads or other difficulties, then the dog will remain in locking engagement and the pin portion and box portion of adjacent joints are difficult to disengage.
BRIEF SUMMARY OF INVENTION
Therefore, it is an object of this invention to provide a riser dog screw with a fail safe mechanism. By providing a fail safe mechanism, the operator has an additional opportunity to remove the riser dog-style connection from the joint in the event that the actuator screw becomes unremovable.
The invention includes a dog-style connector for a marine riser system that connects a box portion and a pin portion of a riser. An actuator housing is affixed to an external surface of the box portion. The actuator housing has an outer bore and a threaded inner bore. An actuator body is threadably received in the inner bore. The actuator body has a hex head on its first end. The actuator body has a threaded fastener bore extending from the first end for receiving a threaded fastener. The actuator body has a second end that has a stem receptacle formed therein. The fastener bore is in communication with the stem receptacle. An actuator head, which includes a flange and a stem, is provided wherein the stem of the actuator head is positioned within the stem receptacle of the actuator body for sliding engagement therewith. Threads formed on the threaded fastener engage a second threaded fastener bore formed in the stem of the actuator head. A dog interfaces with the flange on the actuator head and is slidably mounted with respect to the actuator body for engaging a groove in the pin portion of a riser. A threaded fastener is provided to be threadably received in the threaded fastener bore of the actuator body and the second bore of the actuator head.
In operation, the threaded fastener is placed into the fastener bore in the actuator body. The threaded fastener passes through the fastener bore and into the second bore of the actuator head. The threaded fastener secures the actuator body to the actuator head. The actuator body and the actuator head are made to fit tightly to allow the correct transfer of preload forces to the dog segment. The hex head of the actuator body is then engaged and the actuator body is threaded into the actuator housing until the dog is forced into the grooves of the pin portion of the riser.
The actuator body may become difficult or impossible to remove from the actuator housing due to reasons such as galling of the threads that engage the actuator body with an insert positioned in the actuator housing. To remove an actuator body having galled threads, the retainer ring is removed from the actuator housing, thereby allowing the actuator body and actuator head assembly to lift the dog out of engagement with the pin. The threaded fastener may be rotated by means of a hex opening to disengage the actuator body from the actuator head so that the actuator body and insert may by removed and replaced.
REFERENCES:
patent: 2086431 (1937-07-01), Penick et al.
patent: 3606393 (1971-09-01), Huntsinger et al.
patent: 3647245 (1972-03-01), Hanes et al.
patent: 3768842 (1973-10-01), Ahlstone
patent: 3827728 (1974-08-01), Hynes
patent: 4068865 (1978-01-01), Shanks, II
patent: 4606557 (1986-08-01), Coffey
patent: 4653778 (1987-03-01), Alandy
patent: 5363931 (1994-11-01), Moriarty
patent: 5607019 (1997-03-01), Kent
patent: 1487948 (1977-10-01), None
Christie David Stewart
Hosie Stanley
ABB Vetco Gray Inc.
Bracewell & Patterson L.L.P.
Luu Teri Pham
LandOfFree
Riser dog screw with fail safe mechanism does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Riser dog screw with fail safe mechanism, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Riser dog screw with fail safe mechanism will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2584640