Data processing: measuring – calibrating – or testing – Measurement system – Dimensional determination
Reexamination Certificate
2000-06-21
2002-11-26
Hoff, Marc S. (Department: 2857)
Data processing: measuring, calibrating, or testing
Measurement system
Dimensional determination
C073S625000
Reexamination Certificate
active
06487518
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a thickness reducing management system for pipes in pipe lines which performs a thickness management for the pipes in pipe lines in plants such as an electric power generation plant and chemical plant which are controlled under demineralized water.
2. Conventional Art
Inside pipe lines of an electric power generation plant, steam of high temperature, high pressure and high speed, water of high temperature, high pressure and high speed and two phase fluid of steam and water of high temperature, high pressure and high speed flow, and the pipes in pipe lines are always subjected to a severe environmental circumstance. For this reason, such as erosion and corrosion are induced on the inside surfaces of the pipes in pipe lines and a secular thickness reducing phenomenon is caused thereon. When this thickness reducing phenomenon advances, there arises a danger of leaking the fluid inside the pipe lines which causes a significant problem. The speed of such thickness reducing phenomenon is not uniform with regard to space and time, and further it is understood that the thickness reducing speed also varies depending on a variety of conditions such as, for example, conditions of fluid in the pipe lines and configurations of the pipe lines. Therefore, a variety of experiments with regard to thickness reducing management for pipes in pipe lines were performed until now. Examples of such thickness reducing management systems for pipes in pipe lines in a plant are disclosed in following Japanese patent application laid open prints.
In a method of thickness reduction calculation and evaluation for machines and apparatuses, pipe line arrangement and the like due to erosion and corrosion as disclosed in JP-A-8-178172 (1996), a relationship between such as pipe material components, water quality and fluid flow speed representing parameters of erosion and corrosion inducing the thickness reducing phenomenon and thickness reducing data is analyzed based on thickness reducing measurement data base of more than one type plants and thickness reducing data base from documents data and experimental data which represent general data relating to thickness reducing speed, a mathematical model formula used for the thickness reducing calculation is prepared, in that a relationship between the parameters of erosion and corrosion and the thickness reducing amount is expressed by a function, data base for thickness reducing calculation formula due to erosion and corrosion is newly constructed for every condition of respective erosion and corrosion parameters, thereby, a thickness reducing calculation and evaluation thereof due to erosion and corrosion are realized based on the newly constructed thickness reducing calculation formula.
Further, thickness reducing managing system for pipes in pipe lines as disclosed in JP-A-10-141600 (1998) is for performing a thickness reducing management based on thickness values of the pipes in pipe lines. The thickness reducing managing system is provided with a recording means which records thickness values at a plurality of measurement points determined for every measurement portion; a thickness reducing speed calculating means which calculates thickness reducing speeds at the respective measurement points based on differences between thickness values at the present inspection of the respective measurement points and thickness values at the previous inspection of the respective corresponding measurement points and a plant operation time from the previous inspection to the present inspection; and a remaining life estimating means for estimating remaining life of the pipe lines for every measurement portion based on a maximum value among respective thickness reducing speeds at respective measurement points calculated at the present inspection and a minimum thickness value among respective thickness values for the respective measurement points.
In the thickness reducing calculation and evaluation method due to erosion and corrosion of the machines and apparatuses, pipe line arrangement and the like as disclosed in JP-A-8-178172 (1996), the pipe thickness reducing speed due to erosion and corrosion is expressed with regard many parameters such as temperature effect parameter, fluid flow speed parameter, dissolved oxygen density effect parameter, configuration effect parameter, pH effect parameter, pipe material component parameter and wetness degree effect parameter, however, it is difficult to determine that all of these parameters affect the pipe thickness reducing speed, therefore, the pipe thickness reducing speed calculation formula is not expressed with proper parameters. Further, even if the pipe thickness reducing speed can be calculated properly with the calculation formula, it is impossible to evaluate an inspection interval for the pipe lines based on the pipe thickness reduced amount.
Further, since the thickness reducing managing system for pipes in pipe lines as disclosed in JP-A-10-141600 (1998) performs the pipe thickness reducing management based on the thickness values of the pipes in pipe lines, only the data of a concerned measurement portion including a plurality of measurement points not of the other measurement portions in the pipe lines are used for the calculation of pipe thickness reducing speed and the evaluation thereof, therefore, it was difficult to analyze causes of the thickness reducing of pipes in the pipe line concerned. Further, even when a rapid pipe thickness reducing speed is measured for another pipe line under same condition of water quality and internal fluid state, the data of such rapid pipe thickness reducing speed can not be reflected on the thickness reducing management for the pipes in the pipe line concerned.
In the conventional method, too many parameters which affect the pipe thickness reducing due to erosion and corrosion are used, and in view of the pipe material components and the fluid state in the pipe lines it was difficult to define a proper pipe thickness reducing estimation formula which takes into account its causes, and a thickness reducing management of pipes in pipe lines which takes into account of safety of a plant was impossible.
SUMMARY OF THE INVENTION
An object of the present invention is to resolve the conventional problems as referred to above.
More specifically, an object of the present invention is to provide a thickness reducing management system for pipes in pipe lines in which a thickness reducing speed in the pipes due to erosion and corrosion is properly evaluated based on past and present data and through selection of limited proper parameters affecting thereto, thereby, reliability of remaining life evaluation of the pipes until the thickness thereof reaches to a minimum necessary thickness is enhanced and the pipe thickness reducing condition is correctly evaluated.
Further, an object of the present invention is to provide a thickness reducing management system for pipes in pipe lines in which a proper inspection internal can be set for every measurement portion of the pipe lines depending on the pipe thickness reducing condition and in view of pipe thickness reducing conditions of other measurement portions, therefore, a systematic maintenance and preventive maintenance scheduled for respective pipe lines can be planned, maintenance cost and inspection cost for the plant are reduced and optimized, and safety with regard to leakage of fluid flowing through the pipe lines is enhanced to thereby greatly contribute to a stable electric power supply.
According to one aspect of the present invention proposes a thickness reducing evaluation system for pipes in pipe lines, in particular, for pipes in pipe lines made of either carbon steel or low alloy steel in a plant controlled under demineralized water, which comprises a pipe thickness measurement result data base unit which stores pipe thickness measurement results for respective measurement points performed during inspection of the pipe lines; a point pipe thickn
Aoike Satoru
Hisatsune Masakazu
Kanno Satoshi
Miyazaki Katsumasa
Hitachi , Ltd.
Hoff Marc S.
Mattingly Stanger & Malur, P.C.
Raymond Edward
LandOfFree
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