Hydraulic and earth engineering – Marine structure or fabrication thereof – Structure protection
Reexamination Certificate
1998-10-06
2001-02-20
Lillis, Eileen D. (Department: 3673)
Hydraulic and earth engineering
Marine structure or fabrication thereof
Structure protection
C015S104061, C166S170000, C166S902000
Reexamination Certificate
active
06190090
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an apparatus for use in a pipeline. More specifically, thep present invention relates to a pipeline apparatus whose speed may be controlled.
BACKGROUND OF THE INVENTION
The term “pig”, which is an acronym for pipeline inspection gauges, is used to refer to devices which are propelled along the interior of a pipeline for various purposes. A pig is typically propelled along the pipeline under the pressure of pipeline fluids, namely gas or liquids. In the absence of any speed control means for the pig, the pig will be propelled along the interior of the pipeline at the same speed as the pipeline fluids. The pig may tow other tools such as smart pigs that measure or monitor the condition of the interior of the pipeline, or it may stand alone and, for example, push debris along the pipeline and away from low spots in the pipeline. When used for any of the foregoing purposes, it is desirable that the pig maintain a preset speed in the range of, for example, 3-5 miles per hour (5-8 kilometres per hour).
U.S. Pat. No. 5,208,936 to Campbell describes a variable speed pig for pipelines having two plates with openings where the plates are disposed in the pig housing at opposite ends of flow through passageways. Annular seals seal off the annulus between the pig housing and the pipeline such that pipeline fluids cannot pass through this annulus. Openings in one plate can be aligned with the flow through passageways and with openings in the other plate through rotation of one plate relative to the passageways. Varying the degree of alignment of these openings in relation to the passageways, in turn, varies the amount of pipeline fluids which may pass through the flow through passageways and hence through the pig's housing with the result that the pig's speed can be increased or decreased relative to the pipeline fluid speed as desired.
U.S. Pat. No. 4,769,598 to Krieg et al. describes an apparatus for electromagnetically testing pipeline walls. The apparatus has two hollow cylindrical carriages which are coupled together for movement along the inside of a pipeline. The carriages are of a diameter which is approximately half of the pipeline's diameter and are supported against the pipeline walls by means of rollers disposed around the circumference of the carriages. Two sealing discs are mounted near the front of the first carriage which bear with their circumference against the pipeline wall and shut off the cross-section in an outer annular region at the front end of the first carriage. Between the two sealing discs and a reduced area nose of the first carriage is an annular passage through which pipeline fluids can pass from behind the apparatus to the front. Two perforated discs are mounted near the front of the first carriage and are rotatable in relation to one another. The degree of alignment of the perforations in the two discs permits the speed of the apparatus to be varied by permitting more or less pipeline fluid to pass through the annular passage. A set of brakes is also mounted on the carriage for emergency braking or if the control capabilities of the annular passage are exceeded.
The pigs described in the foregoing Campbell and Krieg patents are limited by the extent to which they are capable of permitting the bypass of pipeline fluid (i.e. through the pig) so as to vary the speed of the pigs. There has therefore developed a need for a pig that is better able to maintain a speed within a preset range in a pipeline, while bypassing any excess pipeline fluids not required for propulsion of the pig.
SUMMARY OF THE INVENTION
In one aspect, the present invention provides an apparatus for use in a pipeline, the pipeline having an interior surface in contact with the apparatus, the apparatus being propelled within the pipeline by pipeline fluids flowing therein, the apparatus comprising: a housing having a front end, a back end, a vertical axis, a longitudinal axis, an entry opening adjacent the back end through which pipeline fluids may enter the housing and an exit opening adjacent the front end through which pipeline fluids may exit the housing, the exit opening being in fluid communication with the entry opening, means disposed peripherally of the housing for sealing engagement of the housing with the interior surface of the pipeline; at least two bonnets having openings, the bonnets extending from the front end of the housing; wherein at least one of the bonnets is movable in relation to the other bonnet; and means for variably aligning the openings in the bonnets so as to permit the exit of pipeline fluids through the exit opening, through the aligned openings and from the housing at an acute angle to the vertical axis.
One of the bonnets may be mounted on a shaft extending from the housing and oriented parallel to the longitudinal axis of the housing.
The bonnets may comprise: a first bonnet of generally cylindrical shape, open at one end, having a plurality of first circumferential openings disposed around its curved surface; a second bonnet having a curved surface for closely fitting about the curved surface of the first bonnet, the second bonnet having a plurality of second circumferential openings disposed around its curved surface.
The first bonnet may also have a plurality of first radial openings disposed around its flat surface; and the second bonnet may also have a plurality of second radial openings disposed around its flat surface.
The means for variably aligning the openings in the bonnets may comprise: sensor means for producing first signals indicative of the speed of the pig; control means responsive to the first signals to produce control signals; drive means responsive to the control signals; at least one of the bonnets being movable by the drive means in relation to the other bonnet so as to vary the degree of alignment between the first openings and the second openings.
The drive means, power supply and the control means may be disposed in a controlmodule located within the housing.
The apparatus may further comprise: a manifold bonnet of cylindrical shape, open at one end, extending from the front end of the housing, the manifold bonnet having a plurality of third circumferential openings disposed around its curved surface. The manifold bonnet may also have a plurality of third radial openings disposed around its flat surface.
The at least two bonnets may comprise: a first bonnet having a cylindrical portion, open at both ends, and a truncated conical portion extending from the cylindrical portion, the first bonnet having a plurality of first circumferential openings disposed around the curved surface of its cylindrical portion; a second bonnet having a cylindrical portion, open at both ends, and a truncated conical portion extending from the cylindrical portion, the second bonnet having a plurality of second circumferential openings disposed around the curved surface of its cylindrical portion; one of the bonnets being mounted so that it closely fits about the other bonnet. The first bonnet may also have a plurality of first radial openings disposed around its truncated conical portion; and the second bonnet may also have a plurality of second radial openings disposed around its truncated conical portion.
In another aspect, the invention provides an apparatus for use in a pipeline, the pipeline having an interior surface in contact with the apparatus, the apparatus being propelled within the pipeline by pipeline fluids flowing therein, the apparatus comprising: a housing having a front end, a back end, a vertical axis, a longitudinal axis, an entry opening adjacent the back end through which pipeline fluids may enter the housing and an exit opening adjacent the front end through which pipeline fluids may exit the housing, the exit opening being in fluid communication with the entry opening; means disposed peripherally of the housing for sealing engagement of the housing with the interior surface of the pipeline; a shaft mounted on the housing and extending from the front end of the h
Campbell Douglas Clinton
Knights Charles Robert
Varney Brian
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Knights Charles Robert
Lillis Eileen D.
Mayo Tara L.
Tuboscope Pipeline Services Canada, Inc.
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