X-ray or gamma ray systems or devices – Specific application – Absorption
Reexamination Certificate
1999-06-14
2001-05-29
Kim, Robert H. (Department: 2882)
X-ray or gamma ray systems or devices
Specific application
Absorption
C378S060000, C378S163000, C378S205000, C138S132000
Reexamination Certificate
active
06240160
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a system for inspection of pipelines, especially the coupling between parts of the pipe, comprising an x-ray source, a detector device for detection of x-rays, possibly a photographic film being sensitive in the x-ray range, adapted to receive the radiation and to be positioned on the opposite side of the pipe wall or pipeline in relation to the source.
BACKGROUND OF THE INVENTION
Pipelines being used in the oil and gas field are often subject to large strain in the form of stress, pressure and temperature variations. Because of this the pipelines are frequently inspected for displacements, cracks or possible leaks. A known method for performing such inspections is x-ray photographing of the pipeline. Different systems performing such inspections are available on the market.
Flexible pipelines are built to stand the abovementioned strains. A usual structure of flexible pipelines is a multi-layer system of steel pipes with polymer materials between them. The polymer layers include a pressure sheet which hinders diffusion and leakage of the pipeline content out into the environment. It is also demanded that the pressure sheet is able to move relatively freely in relation to the steel pipes, thus not to be subject to unnecessary strain when the pipeline moves. Between the pressure sheet and the steel pipes an anti-creep sheet is often placed in order to keep the pressure sheet from fastening to the steel layers. In the ends of each pipe part a coupling part is comprised which among other things may comprise a sealing or a packing ring providing a seal between the pipelines and also between the pressure sheets.
A problem relating to the abovementioned structure is that the pressure sheet has shown a tendency to contract and thus be drawn away from the sealing ring, making the pipeline leaky.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a system to be able to detect relative displacements between parts in a pipe system. It is especially preferred to provide a system being capable of detecting and measuring displacements in polymer layers or the like between steel layers in a pipeline, especially in the vicinity of the coupling points between the different pipe elements.
The present invention is a system for inspecting movable or deformable layers in pipelines, comprising an x-ray radiation source positioned on one side of a pipeline or a wall of the pipeline, a detector device or a photographic film adapted to receive radiation and positioned on the opposite side of the pipeline wall or the pipeline in relation to the radiation source. The pipeline comprises at least a first material layer and a second material layer and at least one movable or deformable third material layer positioned between the first and second material layers, the third material layer being softer than the first and second material layers. The third material layer includes indicators, the indicators having a differing absorption of radiation from the third material layer.
The invention may further be defined wherein the indicators have a length larger than their thickness or width.
Further, the indicators may comprise wires or strings of a fourth material, the wires or strings having a thickness approximately one third of the thickness of the third material layer.
The pipeline in the present system may include more than two material layers that are harder than the third material layer. The more than two layers are alternating and separated by different ones from a plurality of third material layers. At least two of the third material layers include indicators.
Further, the indicators in each of the third material layers may have a different shape.
Imaging of the pipeline in the present invention may be performed from a plurality of directions, and a tomographic picture of the pipeline may be made from this imaging.
The pipeline may comprise coupling points between two parts of the pipeline. The pipeline at each of the coupling points may comprise one or more sealing rings, the sealing rings including indicators.
Each third material layer of the present invention may comprise one or more layers of different materials, these layers of different materials forming pressure sheets or anti-creep sheets.
Another embodiment of the present invention is a pipe section comprising a first material layer, a second material layer and at least one movable or deformable third material layer. The third material layer is positioned between the first and second material layers and is softer than the first and second material layers. The third material layer includes indicators having a differing absorption of radiation from the third material layer.
Yet another embodiment of the present invention is a method for inspecting movable or deformable layers in pipelines. The method comprises the steps of positioning an x-ray radiation source on one side of a pipeline or a wall of the pipeline and detecting radiation on the opposite side of the pipeline wall or the pipeline in relation to an x-ray radiation source. The pipeline comprises at least a first material layer and a second material layer and at least one movable or deformable third material layer. The third material layer is positioned between the first and second material layers and is softer than the first and second material layers. The third material layer includes indicators having a differing absorption of radiation from the third material layer.
This way a simple system is obtained for inspecting pipelines being mainly based upon already available equipment, the implementation of which in new (and existing) pipe systems being easy and relatively cheap.
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Patent Abstracts of Japan, (JP 60-244843), vol. 10, No. 116, p. 452 (Dec. 4, 1985).
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Daaland Alf
Holen Svein Åge
Den Norske Stats Oljeselskap A.S.
Dunn Drew A.
Foley & Lardner
Kim Robert H.
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