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LEAF SPRING RETRACTION OF LOCKING DOGS IN RISER COUPLING SYSTEM

IP.com Disclosure Number: IPCOM000246285D
Publication Date: 2016-May-24
Document File: 4 page(s) / 1M

Publishing Venue

The IP.com Prior Art Database

Abstract

The invention relates to coupling connection for drilling riser system in oil and gas production and design improvements therefor. The invention proposes a new design of coupling for retraction of locking dogs for drilling riser system. The new design includes leaf springs for retrieval of locking dogs from engagement. The leaf springs are two flat or curved plates mounted to the back of the load dog that extend into milled slots in the box coupling. When the dogs are fully engaged the leaf springs deflect a nominal amount to create a predetermined drive-off preload. When the cam ring is lifted, the leaf springs drive-off the dog by exerting force on the coupling at four separate locations. The advantages of the invention include eliminating the issue of stuck dogs in riser coupling joints and lessening rig down time.

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LEAF SPRING RETRACTION OF LOCKING DOGS IN RISER COUPLING SYSTEM

BACKGROUND

The invention relates to coupling connection for drilling riser system in oil and gas production and design improvements therefor. In drilling riser system, box and pin couplings are connected downward to a cam ring. The couplings use multiple dogs for load transfer across the joint. Fastening the cam ring to the coupling moves the dogs radially inward and these lock up with mating teeth profiled on the pin. While removing the coupling, once the cam ring is moved upward, the dogs are supposed to retract, permitting removal of the riser pin. However, in this design, there is a possibility that the dogs may remain stuck in position because of friction or other reasons. This presents a serious operational problem, since the dogs would have to be forced out mechanically by attaching a lever to them by welding or other means. To overcome this problem there is a need for a more efficient coupling design for riser system.

BRIEF DESCRIPTION OF DRAWINGS           

The invention discloses a new design of coupling system with leaf spring retraction of locking dogs for drilling risers, wherein:

FIG. 1 illustrates dual leaf spring arrangement for drilling riser system coupling.

FIG. 2 illustrates the magnified view of the dual leaf spring.

FIG. 3 illustrates the retracting dog by spring action.

FIG. 4 illustrates the retracting dog by vacuum release.

DETAILED DESCRIPTION

The invention proposes a new design of coupling for retraction of locking dogs for drilling riser system. As shown in FIG. 1, the coupling includes a flange to which a cam ring is fastened. The new design includes leaf springs for retrieval of locking dogs from engagement. The leaf springs are two flat or curved plates mounted to the back of the load dog that extend into milled slots in the box coupling as shown in FIG. 1 and FIG. 2.

FIG. 1: Dual leaf spring retrieval for drilling riser system

A magnified view of the leaf spring is shown in FIG. 2. As shown in FIG. 2, in one design, the leaf springs are fastened to the dog by four screws. The springs therefore interact with the coupling at four points for equal force distribution.

FIG. 2...