Method and system for monitoring the performance of a pipe containing a pressurised fluid

• US 20060217902A1
• Filed: 03/11/2004
• Published: 09/28/2006
• Est. Priority Date: 03/11/2003
• Status: Active Grant

• Current Assignee: Oxand
• Original Assignee: Oxand
• Inventors: Bernard, Olivier, Gerard, Bruno
• Granted Patent: US 7,561,976 B2
• Time in Patent Office: Days
• US Class Current: 702/47
• CPC Class Codes: G01H 13/00 Measuring resonant frequency
• CPC Class Codes: G01M 5/0025 of elongated objects, e.g. pipes, masts, towers or railways G01M5/0058 takes precedence
• CPC Class Codes: G01M 5/0041 by determining deflection or stress
• CPC Class Codes: G01M 5/0066 by exciting or detecting vibration or acceleration vibration testing of structures G01M7/00

Abstract

A method of monitoring the performance of a pipe containing a pressurised fluid, the pipe including at least one current zone and singular zones. The method includes: the static monitoring of a pre-determined number of singular zones, in order to obtain circumferential dilatation information; and the calculation of the effective stiffness k(ti) of the pipe and of the measured residual steel section (As(ti) of same, using the above-mentioned circumferential dilatation information. The method can also include the dynamic monitoring of the pipe, in order to obtain information relating to the natural vibration frequencies and modes thereof.

Claims

1. Method for monitoring the performance of a pipe containing a pressurized fluid, this pipe comprising at least one continuous run zone and singularity zones, characterized in that it comprises:

a static monitoring of a predetermined number of singularity zones and/or continuous run zones, in order to provide circumferential expansion information, and

a calculation of the effective stiffness K(ti) of the pipe and its measured residual steel cross-section As(ti) using said circumferential expansion information.

2. Method according to claim 1, characterized in that it also comprises a dynamic monitoring of the pipe in order to provide information relating to the vibration eigen modes and frequencies of said pipe, and in that this information relating to eigen modes and frequencies is also used to calculate the stiffness K(ti) and the measured residual steel cross-section As(ti) of the pipe.

3. Method according to claim 1, characterized in that it also comprises:

a process of predicting the temporal evolution A'"'"'s(t>

ti) of an estimator A'"'"'s(ti) of the residual steel cross-section, this prediction being made on the basis of a model of the corrosion and the mechanical performance of the pipe,

a comparison between the measured residual steel cross-section (As(ti) and the estimator A'"'"'s(ti) of the residual steel cross-section, and

an updating of the corrosion model, when the difference between said measured residual steel cross-section As(ti) and said estimator of the residual steel cross-section A'"'"'s(ti) is greater than a predetermined precision.

4. Method according to claim 3, characterized in that the prediction process is organized so as to integrate, in the phase of updating the corrosion model, information coming from an external source.

5. Method according to claim 3, characterized in that it also comprises a comparison of the measured value As(ti) of the residual steel cross-section with a limit criterion of mechanical strength (CL), this comparison being followed by:

either a transmission of information for immediate replacement of a section of said pipe corresponding to the monitored zones, when this measured value As(ti) is less than said limit criterion for mechanical strength (CL),

or a calculation of the remaining service life D(ti) of said pipe.

6. Method according to claim 5, characterized in that it also comprises a comparison of the measured value As(ti) of the residual steel cross-section with an alarm criterion (CA) associated with the mechanical strength of said pipe, this comparison being followed by:

either a transmission of information for reinforcement and subsequent replacement of a section of said pipe corresponding to the monitored zones, when this measured value As(ti) is less than said alarm criterion (CA),

or a calculation of operating time before the alarm Da(ti) of said pipe actuates.

14. Method according to claim 2, characterized in that it also comprises:

a process of predicting the temporal evolution A'"'"'s(t>

ti) of an estimator A'"'"'s(ti) of the residual steel cross-section, this prediction being made on the basis of a model of the corrosion and the mechanical performance of the pipe,

a comparison between the measured residual steel cross-section (As(ti) and the estimator A'"'"'s(ti) of the residual steel cross-section, and

an updating of the corrosion model, when the difference between said measured residual steel cross-section As(ti) and said estimator of the residual steel cross-section A'"'"'s(ti) is greater than a predetermined precision.

15. Method according to claim 4, characterized in that it also comprises a comparison of the measured value As(ti) of the residual steel cross-section with a limit criterion of mechanical strength (CL), this comparison being followed by:

either a transmission of information for immediate replacement of a section of said pipe corresponding to the monitored zones, when this measured value As(ti) is less than said limit criterion for mechanical strength (CL),

or a calculation of the remaining service life D(ti) of said pipe.

7. System for monitoring the performance of a pipe containing a pressurized fluid, this pipe comprising at least one continuous run zone and singularity zones, characterized in that it comprises:

a device for static monitoring of a predetermined number of singularity zones and/or continuous run zones in order to provide circumferential expansion information, and

means for calculating the effective stiffness K(ti) of the pipe and its measured residual steel cross-section As(ti) using said circumferential expansion information.

8. System according to claim 7, characterized in that it also comprises a device for dynamic monitoring of the pipe in order to provide information on eigen vibration modes and frequencies of said pipe, this information on eigen modes and frequencies being used by the means for calculation of the effective stiffness K(ti) and of the measured residual steel cross-section As(ti).

9. System according to claim 8, characterized in that it also comprises:

means for predicting the temporal evolution A'"'"'s(t>

ti) of an estimator A'"'"'s(ti) of the residual steel cross-section, this prediction being made on the basis of a model of the corrosion and the mechanical performance of the pipe,

means for comparing the measured residual steel cross-section (As(ti) and the estimator A'"'"'s(ti) of the residual steel cross-section, and

means for updating the corrosion model, when the difference between said measured residual steel cross-section As(ti) and said estimator of the residual steel cross-section A'"'"'s (ti) is greater than a predetermined precision.

10. System according to claim 7, characterized in that the static monitoring device comprises means for measuring longitudinal deformations of a section of the pipe and means for measuring circumferential deformations of said section.

11. System according to claim 9, characterized in that the dynamic monitoring device comprises seismometry means for measuring displacement speeds at a predetermined number of points on the pipe.

12. System according to claim 7, characterized in that it also comprises means for pre-processing raw data provided by the static and/or dynamic monitoring device, these pre-processing means being designed to calculate an average deformation over a given period and average eigen frequencies in the operating phase.

13. System according to claim 7, characterized in that it also comprises:

means for predicting the temporal evolution A'"'"'s(t>

ti) of an estimator A'"'"'s(ti) of the residual steel cross-section, this prediction being made on the basis of a model of the corrosion and the mechanical performance of the pipe,

means for comparing the measured residual steel cross-section (As(ti) and the estimator A'"'"'s(ti) of the residual steel cross-section, and

means for updating the corrosion model, when the difference between said measured residual steel cross-section As(ti) and said estimator of the residual steel cross-section A'"'"'s (ti) is greater than a predetermined precision.