Photographic pipeline inspection apparatus including an optical port wiper

#A photographic apparatus has heretofore been developed for obtaining a record of the internal condition of a pipeline and it has been found to be highly advantageous, especially in connection with the testing of offshore pipelines used for transporting natural gas in its raw state. Natural gas cannot be safely treated offshore and may produce corrosion when transported in its raw state through steel pipe of a pipeline, especially when the temperature is relatively high as is often the case. Natural gas in its raw state may include a combination of carbon dioxide and free water which is operative to produce carbonic acid and which will corrode steel. The effect can be augmented by an erosion effect when the rate of flow is high and at bends and over weld beads or the like where the flow is turbulent.

#The effect of such corrosion and erosion as well as other defects can eventually lead to complete failure of the pipe. If such defects can be detected at an early time, it is possible to repair the pipe or otherwise take corrective measures. For example, it is possible to move devices known as "pigs" through a pipe and by moving a series of such pigs through a pipe it can be cleaned, etched, washed, dehydrated and then coated with a protective coating such as an epoxy.

#In the apparatus heretofore developed, an image is projected through a film plane from an internal surface area of the pipe along a viewing axis which is normal to the axis of the pipe, a generally rectangular image being used in the film plane which corresponds to a generally rectangular internal surface area of the pipe. With this arrangement, it is possible to obtain a photographic record which can be accurately interpreted and which indicates when repair or maintenance procedures are necessary. Preferably, the camera and associated optical means and illumination means are located within a chamber between forward and rearward cup assemblies in a device which is movable through the pipeline by the pressure of fluid within the pipeline.

#FIG. 1 is a side elevational view illustrating photographic pipeline inspection apparatus which includes an optical port and a wiper assembly according to the invention, the apparatus being shown as it may be positioned within a pipeline;

#FIG. 2 is a bottom plan view of the optical port and the wiper assembly of the apparatus of FIG. 1 looking from a section line as indicated by line II--II in FIG. 1;

#FIG. 3 is a side view of the optical port and wiper assembly shown in FIG. 2; and

#Reference numeral 10 generally designates pipeline inspection apparatus which includes a camera mounted above an optical port 11 which is kept clear by a wiper assembly 12 constructed and mounted in accordance with the invention. The illustrated apparatus includes a "pig" device 13 which includes a central housing 14 supporting the optical port 11 and protectively carrying the camera therewithin. The central housing 14 also supports a pair of strobe lights which are mounted behind a pair of illumination posts 15 and 16.

#The device 13 is movable longitudinally through a pipeline including a pipe 18 as shown and it includes two forward cups 19 and 20 and two rearward cups 21 and 22 which are respectively disposed in front of and behind the central housing 14. At least one and preferably both of the forward and rearward cup assemblies have weight means associated therewith for establishing an angular orientation of the device 13 such that a viewing axis is established relative to a vertical plane through the pipe axis. The viewing axis is preferably vertical in most applications, so that a photograph is obtained of the lower inside surface of the pipe where flaws are most likely to occur.

#The illustrated optical port 11 includes a circular glass window 24 which is held by a retainer plate 25 and which has a surface 26 exposed to the ambient conditions within the pipeline. Droplets or layers of liquid and/or semi-solid or solid particles of debris may adhere to the surface 26 to attenuate, reflect and/or refract light, thereby affecting transmission of light from the illuminated surface of the pipe toward the camera. As a result, the images of actual defects may be obscured or an image may be produced which falsely indicates a defect which does not exist. Such inaccurate results cannot usually be detected from the photograph even when it is very carefully examined and as a result, necessary repair or maintenance procedures may not be made or unnecessary procedures may be instituted.