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US 6,549,857 B2Granted
Methods for detecting leaks in pressurized piping with a pressure measurement system
AssigneeVista Research, Inc.
InventorsMichael R. Fierro, Joseph W. Maresca, Jr.
Life of this patent
Estimating the term…
Abstract
A method of detecting a leak in a pressurized pipeline system, in which a measurement is performed to determine the difference in the rate of change of pressure due to a leak between one pressure level and at least one other pressure level, after compensation has been made for thermally induced changes in the pressure.
Claims55
A method for use in detecting a leak in a pipeline system comprising:
- measuring a difference in a rate of change of pressure due to a leak between one pressure level and at least one other pressure level after compensation has been made for thermally induced changes in the pressure in a pressurized pipeline system, including the steps of
- (a) pressurizing said pipeline system to a first pressure level and determining a set of first pressure data by measuring a change in pressure in the pipeline system that occurs over a first measurement period;
- (b) pressurizing said pipeline system to at least a second pressure level and determining a set of second pressure data by measuring a change in pressure in the pipeline system that occurs over at least a second measurement period;
- and
- (c) computing a difference in a temperature compensated rate of change of pressure between a first pressure level during said first period and a pressure level during said second period, said computing performed on said first and second pressure data and including a correction for thermally induced non-linear changes of pressure between the measurement periods, wherein the difference in the temperature compensated rate of change of pressure between the pressure levels is computed from the rate of change of pressure calculated from said first and second data and at least one higher order derivative of the pressure data.
2 more elements
A method for estimating an error in a measurement of the difference in the rate of change of pressures between different pressures, comprising the steps of:
- (a) pressurizing a pipeline system to a first pressure level and measuring changes in pressure of product in the pipeline system that occur over a first measurement period to obtain first measurement data;
- (b) pressurizing said pipeline system to at least a second pressure level and measuring changes in pressure in the pipeline system that occur over at least a second measurement period to obtain second measurement data;
- (c) computing the difference in the temperature compensated rate of change of pressure between one pressure level and at least one other pressure level from said first and second measurement data and wherein said first and second measurement data are corrected for thermally induced non-linear changes of pressure between the measurement periods;
- and
- (d) estimating the error by using at least two of the measurement periods wherein the pressure level is initially the same and the error is estimated from the difference in the changes of pressure measured during the measurement periods when the pressure level is initially the same.
2 more elements
A method for use in detecting a leak in a pipeline system comprising:
- estimating an error in a measurement of the difference in rate of change of pressures between different pressure levels on a pressurized pipeline system, said estimating including the steps of
- (a) pressurizing said pipeline system to a first pressure level, and measuring changes in pressure in the pipeline system that occur over a first measurement period;
- (b) pressurizing said pipeline system to at least a second pressure level, and measuring changes in pressure in the pipeline system that occur over at least a second measurement period;
- (c) computing a difference in a temperature compensated rate of change of pressure between one pressure level and at least one other pressure level from the measured pressure data at the pressures, including a correction for the thermally induced non-linear changes of pressure between the measurement periods, wherein the difference in the temperature compensated rate of change of pressure between the pressure levels is computed from the rate of change of pressure measured during the measurement periods, said rate of change being a first derivative of the pressure data, and said difference additionally being computed from higher order derivatives of the pressure data;
- and
- (d) estimating the error by computing at least a next higher order derivative of the pressure data than is used in the computation of difference in rate of change of pressures, and multiplying said next higher order derivative by the time between the measurement periods.
3 more elements
A method for use in detecting a leak in a pipeline system comprising:
- measuring the difference in a rate of change of pressure due to a leak between one pressure level and at least one other pressure level, after compensation has been made for thermally induced changes in the pressure of liquid product in a pressurized pipeline system, said measuring including the steps of
- (a) pressurizing said pipeline system to a first pressure level and measuring changes in pressure of product in the pipeline system that occur over a first measurement period;
- (b) pressurizing said pipeline system to a second pressure level and measuring changes in pressure of product in the pipeline system that occur over a second measurement period;
- (c) pressurizing said pipeline system to a third pressure level that is different than the first pressure level and measuring changes in pressure of product in the pipeline system that occur over a third measurement period;
- and
- (d) computing the difference in temperature compensated rate of change of pressure between a pressure level that is between the second pressure level and the first and third pressure levels, including a correction for the thermally induced non-linear changes of pressure between the measurement periods, wherein the difference in the temperature compensated rate of change of pressure between the pressures is computed by subtracting the time-weighted rate of change of pressure measured during the second measurement period from the time-weighted average of the rate of change of pressure measured during the first and third measurement periods.
3 more elements
A method for use in leak detection in a pipeline system comprising:
- estimating a systematic bias error due to pressure induced temperature perturbations during measurements of a difference in rate of change of pressures between different pressure levels on a pressurized pipeline system including the steps of
- (a) pressurizing said pipeline system to a first pressure level, and measuring changes in pressure in the pipeline system that occur over a first measurement period;
- (b) pressurizing said pipeline system to at least a second pressure level, and measuring changes in pressure in the pipeline system that occur over at least a second measurement period;
- and
- (c) computing the difference in the temperature compensated rate of change of pressure between one pressure and at least one other pressure from the measured pressure data at the pressures, including a correction for the thermally induced non-linear changes of pressure between the measurement periods;
- wherein the measurements are conducted when the pressurized pipeline system is known not to be leaking to obtain the systematic bias error for the pressure level, line volume, and liquid at which the measurements are made.
3 more elements
A method for use in detecting a leak in a pipeline system comprising:
- estimating a systematic bias error due to pressure induced temperature perturbations during measurements of a difference in rate of change of pressures between different pressure levels on a pressurized pipeline system, said estimating including the steps of
- (a) pressurizing said pipeline system to a first pressure level, and measuring changes in pressure of product in the pipeline system that occur over a first measurement period;
- (b) pressurizing said pipeline system to at least a second pressure level, and measuring changes in pressure in the pipeline system that occur over at least a second measurement period;
- and
- (c) computing the difference in the temperature compensated rate of change of pressure between one pressure level and at least one other pressure level from the measured pressure data at the pressures, including a correction for the thermally induced non-linear changes of pressure between the measurement periods;
- wherein the measurements are conducted on at least one pressurized pipeline system that may be different from the one being tested and is known not to be leaking, to obtain the systematic bias error over the range of and for the pressure levels, line volumes, and liquids at which the measurements are made.
3 more elements
A method use in detecting a leak in a pipeline system comprising:
- estimating a systematic bias error due to pressure induced temperature perturbations during measurements of a difference in rate of change of pressures between different pressure levels on a pressurized pipeline system, said estimating including the steps of
- (a) pressurizing said pipeline system to a first pressure level, and measuring changes in pressure in the pipeline system that occur over a first measurement period;
- (b) pressurizing said pipeline system to at least a second pressure level, and measuring changes in pressure in the pipeline system that occur over at least a second measurement period;
- (c) computing the difference in the temperature compensated rate of change of pressure between one pressure level and at least one other pressure level from the measured pressure data at the pressure levels, including a correction for the thermally induced non-linear changes of pressure between the measurement periods, wherein the difference in the temperature compensated rate of change of pressure between the pressures is computed from the rate of change of pressure measured during the measurement periods (first derivative of the pressure data or rate of change of pressure) and higher order derivatives of the pressure data;
- and
- (d) using a model to estimate the thermally induced pressure changes that would be measured on a pipeline system without a leak to obtain the systematic bias error for the pressure level, line volume, and liquid at which the model estimates are made.
3 more elements
A method for use in leak detection comprising:
- estimating a systematic bias error due to pressure induced temperature perturbations during measurements of a difference in a rate of change of pressures between different pressures on a pressurized pipeline system containing liquid product, said estimating including the steps of
- (a) changing the pressure level in the pipeline system from a first pressure level to a second pressure level, and measuring changes in pressure in the pipeline system that occur over a first measurement period;
- (b) changing the pressure level in the pipeline system from the second pressure level to a third pressure level, the difference between the third pressure level and the second pressure level being approximately equal to the difference between the second pressure level and the first pressure level, and measuring changes in pressure in the pipeline system that occur over a second measurement period;
- (c) changing the pressure level in the pipeline system from the third pressure level to approximately the second pressure level, and measuring changes in pressure in the pipeline system that occur over a third measurement period;
- (d) computing the difference in temperature compensated rate of change of pressure between the second and third pressure levels during the first and second measurement periods and the third and second pressure levels during the second and third measurement periods, including a correction for the thermally induced non-linear changes of pressure between the measurement periods;
- and
- (e) subtracting the second and third pressure levels during the first and second measurement periods from the third and second pressure levels during the second and third measurement periods to obtain the systematic bias error.
4 more elements
A method for use in leak detection comprising:
- estimating an error in a measurement of a difference in rate of change of pressures between different pressure levels in a pipeline system, said estimating including the steps of
- (a) pressurizing said pipeline system to a first pressure level and measuring changes in pressure in the pipeline system that occur over a first measurement period;
- (b) pressurizing said pipeline system to at least a second pressure level and measuring changes in pressure in the pipeline system that occur over at least a second measurement period;
- (c) computing the difference in the temperature compensated rate of change of pressure between one pressure level and at least one other pressure level from the measured pressure data at the pressure levels including a correction for the thermally induced non-linear changes of pressure between the measurement periods;
- (d) computing the difference between the second derivatives of the pressure data during two measurement periods;
- and
- (e) estimating the error as a percentage of the difference obtained in (d).
4 more elements
Dependencies are inferred from the claim text.