Ships – Building – Freighters
Reexamination Certificate
2000-02-04
2001-06-05
Sotelo, Jesus D. (Department: 3617)
Ships
Building
Freighters
C220S901000, C137S256000
Reexamination Certificate
active
06240868
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to containment structures and methods of manufacture thereof, particularly for the marine transport and storage of compressed natural gases.
BACKGROUND OF THE INVENTION
The invention relates particularly to the marine gas transportation of compressed gas. Because of the complexity of existing marine gas transportation systems significant expenses are ensued which render many projects uneconomic. Thus there is an ongoing need to define storage systems for compressed gas that can contain large quantities of compressed gas, simplify the system of complex manifolds and valves, and also reduce construction costs. This specific system, which is a unique development of the more general systems described in the above patent application, purports to do all three.
SUMMARY OF THE INVENTION
In an aspect of the invention, there is provided a containment structure comprising a continuous coiled pipe formed in at least a first layer and a second layer lying on top of the first layer, coiled pipe in the second layer lying directly on top of and aligned with the coiled pipe in the first layer, apart from a first transition zone in which coiled pipe in the first layer rises to form part of the second layer and cross coiled pipe in the first layer.
In a further aspect of the invention, there is provided a method of forming a containment structure, comprising forming a continuous coiled pipe in at least a first layer and a second layer lying on top of the first layer, with coiled pipe in the second layer lying directly on top of and aligned with the coiled pipe in the first layer, apart from a first transition zone in which coiled pipe in the first layer rises to form part of the second layer and cross coiled pipe in the first layer.
In a further aspect of the invention, there is provided a containment structure comprising a continuous constant diameter coiled pipe formed in a single layer of alternating constant radius circle segments, in which each circle segment covers 360
degrees, with each succeeding circle segment being 1
pipe diameters greater in radius than a preceding circle segment, where n is greater than 1.
The containment structure of the invention is particularly suited for use as a gas storage system, particularly adapted for the transportation of large quantities of compressed gas on board a ship (within its holds, within secondary containers) or on board a simple barge (above or below its deck, within secondary containers). The coiled pipe is preferably formed of long, primarily circularly curved sections of small diameter steel pipe. The pipe, generally smaller than 8 inches may be coiled in a specific manner within a simple circular container.
In one embodiment, the diameter of the container is about 50 feet and it is about 10 feet high. Approximately 10 miles of pipe or more may be coiled and stacked within the container. The coiling is continuous and there are no valves or interruptions from the start to the end of the coil.
In one aspect of the invention, the pipe may be viewed as starting at the inside of the bottom layer. It spirals outwards by means of constant curvature constant radius segments, preferably semi-circles, which abruptly change their curvature and also their centers of curvature by a small percentage of their gross curvature and their radii respectively. By this means programming and quality control on the bending rollers are kept constant and simple for relatively long periods of time. When the pipe reaches the outside of the container it is forced by the geometry of the container to climb up to the second layer and then start an inwards spiral. After two semi-circular arcs the pipe follows a transition curve which takes it across two pipes immediately below, in a distance of about 12 pipe s. This distance is relatively short and thus vertical stacking stresses at crossover points are minimized. By transitioning two pipes beneath and then by spiraling back out one of the pipe, immediately above the first and subsequent odd layers, a net inwards spiral gain of one pipe is thus achieved. Thus the odd layers spiral outwards and the even layers spiral inwards. When the pipe reaches the inside of the circular container, in even layers, it rises to the odd layers above and its projected plan geometry becomes the same as the geometry of the first layer. Thus the odd layers are composed entirely of semicircles and the even layers are composed of semicircles with very short transition zones.
The invention includes both the containment structure produced by the layered coiled pipes, which lie directly upon each other except for the transition zone, and the method of coiling the pipes to obtain the structure.
The gas storage system of this invention has many advantages, some of which are noted in earlier patents filed by two of the inventors (U.S. Pat. Nos. 5,839,383and 5,803,005). First, the pipe is small and the severity of failure is greatly reduced. Possibly also the probability of failure is also reduced. Second, the technology for the production of long straight and subsequently constantly curved pipe is well known and inexpensive. Third, the system is continuously inspectable by means of an internal pig. Fourth, complicated curved features are absent for about 97% of the coiled length. Fifth, the coiled layout and vertical stacking arrangement reduce gravitational stresses and ship motion stresses to a small fraction of the pipe capacity, even when stacked about 20 to 30s high. All of these features lead to great cost reductions.
Other features and advantages of the invention become apparent when viewing the drawings and upon reading the detailed description.
REFERENCES:
patent: 5803005 (1998-09-01), Stenning et al.
patent: 5839383 (1998-11-01), Stenning et al.
patent: 6003460 (1999-12-01), Stenning et al.
patent: 2198358 (1996-10-01), None
patent: 2259429 (1997-09-01), None
patent: WO97/16678 (1996-10-01), None
patent: WO98/14362 (1997-09-01), None
patent: WO99/19203 (1997-10-01), None
Cran James A.
Fitzpatrick P. John
Stenning David G.
Lambert Anthony R.
Sotelo Jesus D.
Wild Rose Holdings Ltd.
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