Scanning method and apparatus comprising a buoyancy material for scanning a pipeline or a process vessel
The invention discloses a scanning method and apparatus suitable for scanning a pipeline or process vessel in which a beam of gamma radiation from a source is emitted through the vessel to be detected by an array of detectors which are each collimated to detect radiation over a narrow angle relative to the width of the emitted radiation beam.
1. A method of inspecting an underwater pipeline to determine wall thickness or information about contents of the underwater pipeline, the method comprising:
interposing the underwater pipeline between a gamma radiation source and an array of detector units, the gamma radiation source and the array of detector units being mounted in a fixed relationship with each other on a support so that radiation emitted by the gamma radiation source passes along a plurality of paths through a portion of the underwater pipeline and impinges upon the array of detector units;
rotating the support, the gamma radiation source, and the array of detector units around a circumference of the underwater pipeline and acquiring data at a plurality of radially offset positions around the underwater pipeline to acquire density data at a variety of angles through the underwater pipeline; and
presenting a representation of the underwater pipeline or contents of the underwater pipeline using the density data;
wherein the support, the gamma radiation source, and the array of detector units are provided on an apparatus that comprises a buoyancy material.
2. The method according to claim 1 , wherein the apparatus is hinged so that the apparatus is configured to be opened and closed around the underwater pipeline.
3. The method according to claim 1 , wherein the representation is a representation of a composition of the underwater pipeline or its contents.
4. The method according to claim 1 , wherein presenting a representation comprises building the representation using tomography algorithms.
5. The method according to claim 1 , further comprising detecting a void in the underwater pipeline.
6. The method according to claim 1 , further comprising detecting a crack in the underwater pipeline.
7. The method according to claim 1 , further comprising detecting wall thinning in the underwater pipeline.
8. The method according to claim 1 , further comprising detecting a gas hydrate within the underwater pipeline.
9. The method according to claim 1 , further comprising detecting scale within the underwater pipeline.
10. The method according to claim 1 , further comprising detecting a change in density relative to a reference value.
11. The method according to claim 10 , wherein the reference value is a calculated value.
12. The method according to claim 10 , wherein the reference value is a value from an adjacent portion of the underwater pipeline.