Claims
- 1. A method for continuously handling railway mold cars and molding a weight coating onto the exterior surface of pipe segments comprising the steps of:
- providing first railway track means adjacent a pipe coating location;
- coating a plurality of pipe segments to be weight coated with a corrosion resistant composition at said pipe coating location;
- storing said coated pipe segments adjacent said first railway track means while said coating hardens; positioning individual, coated pipe segments to be weight coated into individual mold cars positioned end-to-end upon said first railway track means comprising a unitary pair of rails,
- the mold cars being compatably dimensional with respect to the pipe segments so as to form voids between an exterior surface of the pipe segments and an interior surface of the mold cars;
- translating from one end of the first railway track means a plurality of the individual mold cars and the contained pipe segments onto a first transfer car having a plurality of pairs of rail segments for supporting the plurality of individual mold cars, said translating including
- positioning a first pair of rail segments of the first transfer car into longitudinal registry with the one end of the first railway track means,
- moving one of the individual mold cars onto the first pair of rail segments of the first transfer car,
- positioning at least a second pair of rail segments of the first transfer car into longitudinal registry with the one end of the first railway track means, and
- moving at least another one of the individual mold cars onto at least a second pair of rail segments of the first transfer car;
- transporting said first transfer car, including a plurality of individual mold cars and the pipe segments contained thereon which have been translated onto said first transfer car, upon a second railway track means extending transversely with respect to the first railway track means toward one end of a third railway track means comprising a plurality of pairs of mutually parallel sets of rails, said third railway track means extending longitudinally with respect to said first railway track means and transversely with respect to said second railway track means;
- simultaneously aligning the pairs of rail segments of said first transfer car with respective pairs of rails of said third railway track means;
- translating a plurality of individual mold cars and pipe segments contained thereon from said first transfer car and onto said one end of said third railway track means so that said mold cars are disposed abreast of one another on respective pairs of rails of said third track means;
- filling said voids between the exterior surfaces of the individual pipeline segments and the interior surfaces of said mold cars with a weight coating composition in a fluid state;
- said filling of said voids being effected while said plurality of mold cars are disposed abreast at a void filling location on said third track means, with each mold car being separately operable to receive said weight coating composition;
- transporting abreast upon said third railway track means, said plurality of individual mold cars into a curing kiln;
- at least partially curing said weight coating composition within said curing kiln until the composition is at least self-supporting upon the exterior surfaces of said pipe segments;
- translating abreast a plurality of individual mold cars out of said curing kiln and onto parallel pairs of rails carried by a second transfer car positioned at another end of said third railway means, with said parallel pairs of rails of said second transfer car being simultaneously aligned with said plurality of pairs of rails of said third railway track means;
- opening said mold cars and removing the weight coated pipe segments therefrom so as to empty said mold cars;
- said removing of said weight coated pipe segments being effected while said plurality of mold cars are disposed abreast, with each said mold cars being independently operable to permit said removal of a weight coated pipe segment;
- simultaneously transferring said second transfer car and a plurality of empty mold cars mounted abreast thereupon along a fourth railway track means toward said first railway track means, with said fourth railway track means extending transversely with respect to the first and third railway track means;
- cleaning said plurality of mold cars while said plurality of mold cars are disposed abreast in said fourth railway track means;
- sequentially bringing said parallel pairs of rails of said second car into alignment with another end of the first railway track means; and
- sequentially moving said empty mold cars into end-to-end relation on said first railway track means with said mold cars being then operable to receive further pipe segments to be weight coated.
BACKGROUND OF THE INVENTION
This is a continuation of application Ser. No. 378,045, filed July 11, 1973, now abandoned.
This invention relates to a method and apparatus for weight coating pipe segments. More specifically, the invention relates to a method and apparatus for preparing steel pipe segments to be weight coated and for handling railway mold cars operable to form a cementitious weight coating upon the exterior surface of the pipe segments. Steel pipe segments of this type are typically designed to be connected end-to-end into a pipeline to be laid upon the bed of a body of water.
With the discovery of sizable oil and natural gas deposits offshore and the subsequent successful drilling and production thereof, a problem arose in connection with the most economical means for transporting the crude petroleum and/or natural gas from the producing offshore site to a shore location or collection/transfer terminal.
Often the most economical means for transporting oil and gas between offshore locations has been to establish submerged pipelines extending between the producing and collecting stations. In this connection U.S. Pat. No. 3,280,571; Lawrence U.S. Pat. Nos. 3,390,532; 3,472,034; and 3,487,648; Rochelle et al reissue U.S. Pat. No. Re.27,420; Smith U.S. Pat. No. 3,566,609; Lochridge U.S. Pat. No. 3,606,759; Nolan U.S. Pat. No. 3,645,105 and Jones et al U.S. Pat. No. 3,667,878, all assigned to the assignee of the subject invention, disclose highly effective methods and apparatus for laying a pipeline upon the bed of a body of water.
Although, as previously noted, the pipelines are fabricated from steel conduits, the lines typically displace more water than the weight of the pipe and the oil and/or natural gas to be carried by the line. As a consequence, offshore oil pipelines have a tendency to float within the body of water.
In order to eliminate this buoyant tendency, it has been industry wide practice to coat the exterior of the pipeline with a heavy cementitious weight coating of a thickness suitable to raise the specific gravity of the pipeline per linear foot to a desired preselected degree such as, for example, 1.3.
While various techniques have been at least theorized for applying a weight coating to the exterior surface of pipe segments, the most common practice entails impacting techniques. Such techniques, however, leave room for significant improvement, particularly in terms of weight coating surface finish, concentricity, evenness of depth, etc., as more fully discussed in applicants' previously noted related application which discloses and claims mold assemblies for weight coating pipe segments.
In dealing with large and weighty mold assemblies, of the type discussed in applicants' copending application, it would be desirable to optimize management of the molds and provide a compact, rugged and reliable handling arrangement. In achieving such optimization, such factors as preparing the pipe segments to be weight coated, various stages of the actual weight coating operation, etc. each of which may consume variant time frames, must be considered and advantageously harmonized.
Objects:
It is therefore an object of the invention to provide a novel method for molding a cementitious weight coating onto the exterior surface of a plurality of pipe segments wherein individual steps are mechanised, correlated and arranged in a highly efficient and judicious manner with respect to space utilization and functional systems requirements.
It is a particular object of the invention to provide a novel method and apparatus for handling railway mold cars operable to form a weight coating of cementitious material upon the exterior of pipe segments which is suitable to accommodate and reliably handle extremely large and heavy railway form assemblies.
It is another object of the invention to provide a novel method and apparatus for handling railway mold cars operable to form a cementitious weight coating upon the exterior surfaces of pipe segments, wherein efficient handling and management of the mold cars is optimized.
It is yet another object of the invention to provide a novel method and apparatus for handling railway mold cars operable to form a cementitious weight coating upon the exterior surface of pipe segments wherein the mold cars may be continuously handled in a closed loop system with functions of necessarily variant time intervals advantageously accommodated.
It is a further object of the invention to provide a novel method and apparatus for handling and preparing pipe segments to be weight coated prior to the actual application of a weight coating composition to the pipe segments.
It is still a further object of the invention to provide a novel method and apparatus for translating weighty mold car assemblies upon a compact closed loop railway track system.
It is a specific object of the invention to provide a novel method and apparatus for advantageously handling weight coating mold cars continuously in a closed loop while marrying relatively rapidly performed operations such as applying a wire reinforcing cage to pipe segments with relatively slowly performed operations such as drying the weight coating composition.
Brief Summary:
A method and apparatus, according to a preferred embodiment of the invention, intended to accomplish at least some of the foregoing objects comprises a closed loop railway handling system including a first single railway track for supporting mold cars aligned end-to-end for receiving pipe segments to be weight coated. Power means are provided to translate the mold cars to one end of the unitary railway track and selectively load a plurality of the cars onto a first transfer car assembly. The first transfer car rides upon a second railway track system in a direction normal to the first railway track assembly. The plurality of mold cars are transferred to and then guided onto a third railway track means comprising a plurality of parallel railway rails. The molds receive a weight coating composition and are fed into a longitudinally extended drying kiln to partially cure. Following curing of the weight coating to the point of being self-supporting, the cars are transferred abreast onto a second transfer car means. The second transfer car is mounted upon a fourth railway track system extending generally normal to the first and third railway track assemblies. The mold cars are then transferred to the other end of the unitary track and again aligned thereupon in end-to-end relationship.
The method includes the steps of cleaning, priming, and coating pipe segments with a bituminous composition. The coated pipe segments are wrapped and carefully handled so as not to disturb the bituminous coating. Wire reinforcing cages are formed around the pipe segments and the individual pipe segments are then loaded into individual mold cars positioned end-to-end upon a first railway track assembly. The cars are then translated onto a first transfer car, which rides on a second track means, and are conveyed to a third railway track assembly comprising a plurality of parallel sets of rails. The mold cars are transferred abreast from the transfer car onto the third railway track assembly, filled with a cementitious weight coating material and fed into a curing kiln whereby the cementitious weight coating cures at least until the cement becomes self-supporting. The cars are then translated abreast onto a second transfer car, riding upon a fourth track assembly, positioned at the other end of the third railway means. The molds are opened and the weight coated pipe segments are removed. The empty mold cars are then transferred to the other end of the first railway track assembly where the individual mold cars are sequentially aligned with the other end of the first railway track means and translated onto the first track means in an end-to-end relationship, thus closing the handling loop.
US Referenced Citations (4)
Foreign Referenced Citations (1)
| Number |
Date |
Country |
| 1,093,066 |
Nov 1960 |
DT |
Continuations (1)
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Number |
Date |
Country |
| Parent |
378045 |
Jul 1973 |
|
Patent Grant
3997639
