Measuring and testing – With fluid pressure – Leakage
Patent
1998-04-27
1999-12-14
Noori, Max
Measuring and testing
With fluid pressure
Leakage
73 493, G01M 320, G21C 1700
Patent
active
060002786
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a device for testing flange connections with regard to leakages within a pipe system, e.g. a pipe installation wherein the joints between adjacent individual pipes comprise joint flanges, and wherein a packer is sealingly disposed between opposing end faces of neighbouring pipes at the joint flanges, and wherein, at either side of said packer, an annular groove is formed, the circumference thereof being situated in a lateral plan in respect of the longitudinal axis of the pipes, and whererin the packer, within an area defined by the two parallel annular grooves, is provided with a through-going hole, bringing the annular cavities defined by the two annular grooves and the packer into fluid communication with each other.
Advantageously, the device according to the invention should be applicable in all kinds of flange connections requiring testing in respect of tightness.
Particularly in connection with process installations, even minor leakages in the flange joints of the pipelines represent significant explosion risks. Therefore, testing of flange joints is very important, and such testing is usually carried out at frequent intervals.
When testing pipe installations conventionally within the process industry, it may well take up to a day in order to establish the necessary test pressure, i.e. a pressure of a sufficient magnitude to control whether the flange joints are tight or not. Sufficient test pressure has a value substantially above ordinary process pressure and may be e.g. 500 bars. The process installation is coupled to a pressure gauge. If the pressure gauge shows a pressure drop after test pressure has been built up within the pipe installation, at least one leakage is detected within the installation.
Upon a leakage detection within a process installation, all flange joints, in accordance with conventional technique, must be covered with tape or foam surrounding the flange joints, in order to try to conclude visually where the leakage(s) is/are situated. Subsequently to repairing and sealing the leaking flange joint(s), test pressure once more must be established, prior to relieving the pressure again, and restarting the process installation.
Such as the testing takes place today, namely through a test pressure built up internally in the pipeline, one does not know which one of the two seat faces in the flange joint that is sealing. After demounting the two adjacent joint flanges subsequently to detecting a leakage, the packer is usually discarded because it is not easy to determine whether it is damaged or not. However, such packers, normally consisting of steel, are very expensive to provide, and it is merely due to lack of technology that good packers in many cases unnecessarily are replaced by new ones.
Thus, conventional technique is aimed at pressure testing the entire process installation in respect of exposing leakage, nitrogen often being used as test medium. At the oil field Statfjord A in the North Sea, such a test operation after the plant has been shut down will cost several millions (Norwegian) kroner (crowns) for equipment and nitrogen. If a leakage is detected, the plant must be shut down, repaired and, thereafter, pressure tested once more.
U.S. Pat. No. 2,491,599 deals with a casing anchorage in the form of a flange shaped with a channel through which a test medium can be injected into a cavity defined by sealing rings. The sole feature of this known device that also is appearing in the present invention, is the channel through the flange. In other respects, both the flange connection and the packers used belong to an entirely different kind than the ones used in association with the present invention.
In the device according to U.S. Pat. No. 3,290,047, packers as well as flanges may be formed with channels, namely in order to drain the flange connections. The packers used are quite unfit for use in process installations where the process pressure should have caused the packers to collapse.
GB patent specification No. 1,558,857 and GB published
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