EP0072105A2 - Estimation de la durée de vie d'une conduite - Google Patents

Estimation de la durée de vie d'une conduite Download PDF

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Publication number
EP0072105A2
EP0072105A2 EP82303636A EP82303636A EP0072105A2 EP 0072105 A2 EP0072105 A2 EP 0072105A2 EP 82303636 A EP82303636 A EP 82303636A EP 82303636 A EP82303636 A EP 82303636A EP 0072105 A2 EP0072105 A2 EP 0072105A2
Authority
EP
European Patent Office
Prior art keywords
value
temperature
signal
duct
pressure
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP82303636A
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German (de)
English (en)
Other versions
EP0072105B1 (fr
EP0072105A3 (en
Inventor
Frederick Starr
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
British Gas PLC
Original Assignee
British Gas Corp
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Filing date
Publication date
Application filed by British Gas Corp filed Critical British Gas Corp
Publication of EP0072105A2 publication Critical patent/EP0072105A2/fr
Publication of EP0072105A3 publication Critical patent/EP0072105A3/en
Application granted granted Critical
Publication of EP0072105B1 publication Critical patent/EP0072105B1/fr
Expired legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17D—PIPE-LINE SYSTEMS; PIPE-LINES
    • F17D5/00—Protection or supervision of installations
    • G—PHYSICS
    • G07—CHECKING-DEVICES
    • G07C—TIME OR ATTENDANCE REGISTERS; REGISTERING OR INDICATING THE WORKING OF MACHINES; GENERATING RANDOM NUMBERS; VOTING OR LOTTERY APPARATUS; ARRANGEMENTS, SYSTEMS OR APPARATUS FOR CHECKING NOT PROVIDED FOR ELSEWHERE
    • G07C3/00—Registering or indicating the condition or the working of machines or other apparatus, other than vehicles

Definitions

  • the present invention relates to the assessment of the overall lifetime until failure of a duct, particularly a pipe carrying a fluid such as a gas at elevated pressures and temperatures.
  • a method for assessing the overall . lifetime tr until failure of a duct carrying fluid at elevated temperatures and pressures comprising sensing the pressure and temperature of the fluid at selected points in the duct, emitting signals representative of the pressure and temperature, determining the values of pressure and temperature represented by the signals and deriving the value of tr from the values of pressure and temperature.
  • the temperature of the fluid is sensed at a plurality of points in the duct, a temperature signal is derived for each point and a value of tr is derived for each signal.
  • the signals are continuously sampled sequentially and the value of tr is derived for each sampled pressure and temperature signal.
  • each emitted signal is an analogue signal and is converted to a digital signal to enable the value of pressure or temperature to be determined.
  • the analogue signal is a voltage which is converted to pulses of a frequency analogous to the voltage.
  • the pulses are counted during the signal sampling period to provide values of the pressure or temperature.
  • the fraction of life tF(m) of the duct used up between sequential signal samples of the same temperature sensor is determined from the equation Where t1 is the time of the last or current signal sample, t2 is the time of the last but one sample, tr 1 is that value of tr derived from the current temperature signal and tF(m) is integrated to provide an overall fraction ⁇ tF(m) of the life of the duct which has been used up in the period during which the duct has been carrying fluid.
  • the period during which the duct has been carrying fluid is subtracted from the currently derived value of tr so as to provide an indication of the period of the remaining useful life of the duct.
  • the highest currently derived value of tr is taken as the datum.
  • a factor is added to the value of pressure before tr is determined to provide a margin for safety in the currently derived value of tr.
  • the factor is 10% of the value of pressure.
  • the value of the stress to which the duct is being subjected is derived from the pressure value and is utilised together with the temperature value to derive the value of tr.
  • the duct may be a pipe and the derived stress in this case is desirably the hoop stress.
  • the relevant value of the Larson Miller parameter (P) as herein defined is selected from a calibration curve of hoop stress against P for the pipe being tested and the value of tr is derived from the equation:- where C is a constant and T is the current temperature value in °K.
  • the value of tr is printed out and/or displayed.
  • apparatus for assessing the overall lifetime tr until failure of a duct carrying fluid at elevated pressures and temperatures, the apparatus comprising sensors for sensing the pressure and temperature of the fluid at selected points in the duct and for emitting signals representative of the pressure and temperature and means responsive to the signals for determining the values of the pressure and temperature from the signals and for deriving the value of tr from the values of the pressure and temperature.
  • the sensors sense the temperature of the fluid at a plurality of points in the duct and emit a signal for each point, the signal responsive means being adapted to derive a value of tr for each signal.
  • Suitably means are provided to continuously sample the signals sequentially and the signal responsive means is adapted to derive a value for tr for the sampled pressure and temperature signal.
  • sampling means is a multiplexer.
  • each sensor is adapted to emit an analogue signal and means are provided to convert the analogue signal to a digital signal for processing by the signal responsive means.
  • the analogue signal is a voltage and the converter means is adapted to convert the analogue signal to pulses of a frequency analogous to the voltage.
  • the signal responsive means includes a counter for counting the pulses during the signal sampling period to provide values of the pressure or temperature.
  • the signal responsive means is adapted to derive the value of the stress to which the duct is being subjected from the pressure value and to derive the value for tr from the derived stress value and the temperature value.
  • the duct itself may be a pipe and in this case the derived stress is the hoop stress.
  • means are provided to store a calibration of hoop stress against the Larson Miller parameter (P) as herein defined for the pipe being tested and the signal responsive means is adapted to select the relevant value of P corresponding to the derived hoop stress and to derive the value of tr from the equation:- where C is a constant and T is the current temperature value in °K .
  • means responsive to the signal responsive means are provided to print out the value of tr and in another embodiment means may be provided to display the value of tr.
  • the signal responsive means and the store means comprise a computer.
  • tr is the time to failure in hours measured from the instant when the material was first subjected to the stress
  • P and C are constants
  • T is the temperature in °K at which the material is being held while being subjected to the stress.
  • the Larson-Miller curve can be used to determine tr for a pipe carrying a fluid at elevated pressures and temperatures. To do this it is necessary first to establish a standard Larson-Miller curve for the particular material from which the pipe is constructed by plotting the stress to rupture obtained experimentally against the corresponding parameter P. Once this curve has been established, the stress to which the pipe is being subjected in service can be determined and the parameter P corresponding to this stress can be read off from the curve and tr can be calculated from equation (1) above by inserting the relevant values of T and C.
  • hoop stress rr which can be determined from the equation:- where p is the pressure of the fluid carried by the pipe in psi, D is the external diameter of the pipe in inches and t is the wall thickness of the pipe in inches.
  • time to rupture tr can be calculated by measuring the pressure and temperature of the fluid carried by the pipe in service, the time tr being the total time starting from the instant when the pipe first began to carry fluid.
  • the pressure at any point in a fluid is constant, its temperature may vary so that in a length of pipe the temperature of the fluid may be very different at different points along the pipe length. Since the parameter P is directly dependent upon temperature, it will vary along the length of the pipe and thus the time tr will be different for different points in the pipe. It is therefore important for the temperature to be measured at as many points as possible along the pipe length to enable that point at which the rupture time is the shortest to be established.
  • Each calculated value of tr for each temperature sensor point is then used to calculate the fraction of life tF(m) of the pipe used up between sequential signal samples of the same temperature sensor from the equation:- where t1 is the time of the last or current signal sample, t2 is the time of the last but one sample, and tr 1 is that value of tr derived from the current temperature signal.
  • tF(m) is integrated to provide an overall fraction ⁇ tF(m) of the life of the pipe which has been used up in the period during which the duct has been carrying fluid. In this case of course failure of the pipe is predicted when ⁇ tF(m) is.equal to one.
  • tF(m) a direct indication of the remaining useful life of the pipe can be obtained by subtracting the period during which the pipe has been carrying fluid from tr l .
  • the disadvantage with this method is that the value of tr 1 will only be reliable if the fluid has been at a relatively constant pressure and temperature during the period it has been carried by the pipe.
  • the point at which the highest currently derived value of tr has been calculated should be taken as the datum since this is the point at which the pipe will first rupture.
  • a factor is added to the value of pressure (or to the calculated stress) before tr 1 is determined and the applicants have found that a factor of 10% of the measured pressure is an adequate margin.
  • block 1 includes a multiplexer, amplifier and voltage to frequency converter which supply in sequence a series of amplified frequency signals analogous to voltage signals supplied to the multiplexer by a number of sensors.
  • the frequency signals are received by and processed in the central processing unit of a microcomputer 2 together with data in the microcomputer store so as to provide inter alia information on the overall lifetime until failure tr of a duct carrying fluid at elevated temperatures and pressures.
  • the data is supplied to the microcomputer 2 by way of a data teletype 3 and information is output to a printer 4.
  • the multiplexer comprises four analogue multiplexer chips 5 to 8 each of which is supplied with analogue voltage signals from eight sensors.
  • Chip 5 is connected to one pressure sensor P and to seven temperature sensors T1 to T7. Chips 6 to 8 however are each connected to eight temperature sensors T8 to T15, T16 to T23 and T24 to T31 respectively.
  • the pressure sensor may be located at any convenient position in the pipe and the temperature sensors at conveniently spaced intervals along the pipe so as to record the temperature at a multiplicity of points along the pipe.
  • the multiplexer 1 also comprises a 2 to 4 line decoder 9 and a signal selector 10 which together form parallel input-output ports to select one of the 32 signal inputs to the multiplexer chips 5 to 8.
  • the 2 to 4 line decoder 9 receives two input control signals which are decoded to give four "enable" signals to select one of the four multiplexer chips 5 to 8.
  • the signal selector 10 receives three input control signals which are supplied in parallel as three input select signals to the each of the four chips so as to select one of the eight sensor signals in that chip selected by the decoder 9.
  • the decoder comprises two pairs of serially connected inverters 9 to 12 and four 'NOR' gates 13 to 16 which each in turn produce a high output in dependence on the level of the two control input signals to the inverters as shown in the table in Figure 3b.
  • the signal selector comprises three parallel inverters 17 to 19 which respond to the eight combinations of input signals to produce eight combinations of inverted output signals.
  • the decoder 9 enables each chip to be sampled or monitored for 4 seconds and the signal selector samples or monitors each sensor for 0.5 second so that 32 multiplexed inputs of 0.5 second duration are monitored giving a cycle time of 16 seconds.
  • the outputs of the multiplexers 5 to 8 are wired ORed to the input of a low drift instrumentation amplifier 20.
  • the amplifier 20 is connected to the analogue input of a voltage to frequency converter 21.
  • the output of the converter 21 is connected directly to the counter timer circuit channel of the microcomputer 2. This circuit inter alia counts the number of frequency pulses over a fixed time period and hence enable the values of sensed pressure or temperature to be measured.
  • the microcomputer 2 is a Zilog Z80 microcomputer which is programmed to calculate the time tr, the programme residing in 4K bytes of "read only" memory.
  • the microcomputer 2 incorporates a teletype monitor 3 to provide teletype initialisation and a source code contained in several modules as described below.
  • the data areas are initialised on reset (or power up) and the input parameters solicited from the teletype 2.
  • the main programme loop is within this module, supervising the analysis of the data, the synchronisation of the calculations with the input of new readings and the output of results.
  • the parameter P is calculated from pre-input values of P vs log 10 ⁇ by linear interpolation.
  • tr is calculated for each of the 31 temperature sensors.
  • the value of tr may be used either to calculate the fraction of life tF(m) which is integrated as previously described to provide an integral ⁇ tF(m) or the remaining useful life of the pipe may be directly calculated from tr. In this case tr may be calculated with the value of P or if modified by the addition of a factor for safety.
  • the central timer circuit is programmed to interrupt on two channels and both these interrupts are handled by routines in the main module.
  • the timer is interrupted every 25 ms, the clock is incremented and the sensor being monitored at the particular time is read and updated every 0.5 second.
  • the counter is interrupted every 256 pulse counts and the total is incremented and the counter restarted.
  • This module contains the permanent data which accurately defines the system and includes the Data Module.
  • the Data Module contains values of log 10 ⁇ and the corresponding value of P which are input before the fluid is introduced into the pipe.
  • Statement 34 sets aside a storage area to contain the ⁇ D (I) and P D (I) data.
  • the ⁇ D (I) and P D (I) values may be stored permanently if the system is to be dedicated to a particular component material.
  • tr in 44 can be calculated from a P value derived from the pressure or stress value to which 10% of that value has been added to provide a margin for safety.
  • the remaining useful life of the pipe can then be calculated by subtracting the period during which the pipe has been carrying the fluid from tr.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Measuring Fluid Pressure (AREA)
  • Testing Or Calibration Of Command Recording Devices (AREA)
  • Testing Of Devices, Machine Parts, Or Other Structures Thereof (AREA)
  • Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)
EP82303636A 1981-08-04 1982-07-12 Estimation de la durée de vie d'une conduite Expired EP0072105B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB8123818 1981-08-04
GB08123818A GB2103801B (en) 1981-08-04 1981-08-04 Assessing lifetime of duct by measuring fluid pressure and temperature within the duct

Publications (3)

Publication Number Publication Date
EP0072105A2 true EP0072105A2 (fr) 1983-02-16
EP0072105A3 EP0072105A3 (en) 1984-07-18
EP0072105B1 EP0072105B1 (fr) 1987-04-08

Family

ID=10523681

Family Applications (1)

Application Number Title Priority Date Filing Date
EP82303636A Expired EP0072105B1 (fr) 1981-08-04 1982-07-12 Estimation de la durée de vie d'une conduite

Country Status (7)

Country Link
EP (1) EP0072105B1 (fr)
JP (1) JPS5838834A (fr)
CA (1) CA1181522A (fr)
DE (1) DE3276015D1 (fr)
DK (1) DK339182A (fr)
GB (1) GB2103801B (fr)
ZA (1) ZA825050B (fr)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0122578A2 (fr) * 1983-04-19 1984-10-24 Siemens Aktiengesellschaft Méthode de surveilalnce de fatigue d'éléments par exemple dans une centrale atomique
FR2555781A1 (fr) * 1983-11-30 1985-05-31 Gen Electric Appareil et procede de protection de moteurs et de protection de la duree de vie de moteurs
WO1988001081A1 (fr) * 1986-07-29 1988-02-11 Qualitrol Corporation Indicateur de la duree de vie probable d'un transformateur
EP0350614A1 (fr) * 1988-07-15 1990-01-17 Nsq- Hauk Gesellschaft Fuer Qualitaetssicherung Mbh Méthode d'essai pour tuyauteries
EP0527678A1 (fr) * 1991-08-12 1993-02-17 Sames S.A. Procédé de mesure de débit de poudre fluidisée et dispositif de mesure de débit mettant en oeuvre un tel procédé
EP1191470A2 (fr) * 2000-07-27 2002-03-27 Hydroscope Canada Inc. Système pour optimiser l'entretien de conduites d'eau
AU752024B2 (en) * 2000-04-14 2002-09-05 Kabushiki Kaisha Toshiba Method and equipment for assessing the life of members put under high in-service temperature environment for long period
DE102009032859A1 (de) 2009-07-13 2011-01-20 Robert Bosch Gmbh Vorrichtung, Verfahren zur Ermittlung einer Verschleißgröße oder einer Restlebensdauer eines Hydrospeichers sowie entsprechender Hydrospeicher

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE19703709C1 (de) * 1997-01-23 1998-08-27 Mannesmann Ag Verfahren zur Erfassung des Ist-Zustandes eines Behälters, insbesondere Composite-Druckgasbehälter für Fahrzeuge
WO2017194369A1 (fr) 2016-05-09 2017-11-16 Haldor Topsøe A/S Surveillance de tubes chauffés

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4001785A (en) * 1974-02-15 1977-01-04 Asahi Kasei Kogyo Kabushiki Kaisha Apparatus for monitoring changes of multiple inputs
DE2714069A1 (de) * 1976-04-01 1977-10-13 Insurance Tech Bureau Verfahren und einrichtung zum feststellen und analysieren von fehlerquellen
DE2658818A1 (de) * 1976-12-24 1978-07-06 Bea Baugesellschaft Fuer Elekt Diagnose-computer-einrichtung
EP0002232A2 (fr) * 1977-11-25 1979-06-13 IRD MECHANALYSIS, Inc. Système et méthode pour le contrôle du fonctionnement d'un appareil

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5616372A (en) * 1979-07-20 1981-02-17 Nippon Telegr & Teleph Corp <Ntt> Receiver of variable scanning facsimile signal
JPS5764141A (en) * 1980-10-07 1982-04-19 Hitachi Ltd Method and device for foreseening life of apparatus consisting of metallic structure

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4001785A (en) * 1974-02-15 1977-01-04 Asahi Kasei Kogyo Kabushiki Kaisha Apparatus for monitoring changes of multiple inputs
DE2714069A1 (de) * 1976-04-01 1977-10-13 Insurance Tech Bureau Verfahren und einrichtung zum feststellen und analysieren von fehlerquellen
DE2658818A1 (de) * 1976-12-24 1978-07-06 Bea Baugesellschaft Fuer Elekt Diagnose-computer-einrichtung
EP0002232A2 (fr) * 1977-11-25 1979-06-13 IRD MECHANALYSIS, Inc. Système et méthode pour le contrôle du fonctionnement d'un appareil

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
CONTROL AND INSTRUMENTATION, vol. 11, no. 11, December 1979, pages 27,29, London (GB); *
IEEE TRANSACTIONS ON RELIABILITY, vol. R-17, no. 1, March 1968, pages 27-33, New York (USA); *
TRANSACTION OF THE ASME, Paper No. 51-A-36, July 1952, pages 765-775, New York (USA); *

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0122578A2 (fr) * 1983-04-19 1984-10-24 Siemens Aktiengesellschaft Méthode de surveilalnce de fatigue d'éléments par exemple dans une centrale atomique
EP0122578A3 (en) * 1983-04-19 1987-04-01 Kraftwerk Union Aktiengesellschaft Fatigue monitoring method of components, for example in a nuclear power station
FR2555781A1 (fr) * 1983-11-30 1985-05-31 Gen Electric Appareil et procede de protection de moteurs et de protection de la duree de vie de moteurs
WO1988001081A1 (fr) * 1986-07-29 1988-02-11 Qualitrol Corporation Indicateur de la duree de vie probable d'un transformateur
EP0350614A1 (fr) * 1988-07-15 1990-01-17 Nsq- Hauk Gesellschaft Fuer Qualitaetssicherung Mbh Méthode d'essai pour tuyauteries
EP0527678A1 (fr) * 1991-08-12 1993-02-17 Sames S.A. Procédé de mesure de débit de poudre fluidisée et dispositif de mesure de débit mettant en oeuvre un tel procédé
AU752024B2 (en) * 2000-04-14 2002-09-05 Kabushiki Kaisha Toshiba Method and equipment for assessing the life of members put under high in-service temperature environment for long period
EP1191470A2 (fr) * 2000-07-27 2002-03-27 Hydroscope Canada Inc. Système pour optimiser l'entretien de conduites d'eau
EP1191470A3 (fr) * 2000-07-27 2003-06-04 Hydroscope Canada Inc. Système pour optimiser l'entretien de conduites d'eau
DE102009032859A1 (de) 2009-07-13 2011-01-20 Robert Bosch Gmbh Vorrichtung, Verfahren zur Ermittlung einer Verschleißgröße oder einer Restlebensdauer eines Hydrospeichers sowie entsprechender Hydrospeicher

Also Published As

Publication number Publication date
DK339182A (da) 1983-02-05
GB2103801A (en) 1983-02-23
GB2103801B (en) 1985-05-22
ZA825050B (en) 1983-04-27
EP0072105B1 (fr) 1987-04-08
CA1181522A (fr) 1985-01-22
JPS5838834A (ja) 1983-03-07
DE3276015D1 (en) 1987-05-14
EP0072105A3 (en) 1984-07-18

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