RU2247958C2 - Method and device for remote testing of structures - Google Patents

Abstract

FIELD: testing engineering.

SUBSTANCE: method comprises recording signals from measuring units mounted at the sites of structure to be tested and comparing the signals with reference signals. The device comprises measuring units, transducers, connecting lines, and controller.

EFFECT: enhanced reliability of testing.

2 cl, 1 dwg, 6 tbl

Description

The invention relates to measuring technique and can be used for continuous non-destructive testing, assessment and prediction of the technical condition of the structure and engineering structures, for example sections of pipelines, during the entire period of their operation.

The problem of improving technical safety and the stability of the functioning of pipelines is solved in various ways.

A known ultrasonic method for monitoring the stress state of a gas pipeline, based on measuring the increase in stress in the pipe metal (O.O. Fesenko, RN, etc. "Ultrasonic method for monitoring the stress state of gas pipelines", Gas industry. - 2001, No. 5, p. 34-35). The essence of the method is to excite shear and longitudinal waves in the pipe wall, the propagation velocity of which in the metal depends on the level and sign of the current stresses in the pipe. Three sensors are installed at each measuring point: shear waves in the longitudinal direction of the pipe, shear waves in the annular direction and longitudinal waves. This allows you to control the stress level, both in the annular direction of the pipe, and in the longitudinal. (The error in measuring the increase in stress Δ σ according to the results of laboratory tests is ± 1 kg / mm ² ).

The disadvantage of this solution is the impossibility of obtaining complete and reliable information about the state of the pipeline without the use of other assessment methods.

There is a method of preventing leakage of fluid products in pipeline transport, which consists in determining pressure drops and other parameters characterizing leakage in controlled areas by measuring and transmitting measurement data to regional pipeline control centers (RCUs) via communication satellites, by machine (using a computer) calculation of values and locations of leaks, based on a comparison of current measurement data with previously obtained reference data, reception and transmission via communication satellites to the area of emergency sections and implementation of control actions to eliminate leaks (RF application No. 95100443, IPC ⁷ F 17 D 5/00, publ. 10.01.97). During operation of pipelines, pressure data are periodically compared with reference data, which allows to increase the sensitivity and accuracy of control. (About an order of magnitude compared with the case of direct measurements).

A known method of continuous monitoring of the operation of pumping systems for pumping water and oil products, which consists in measuring the pressure at the inlet and outlet of each electric pump, the pressure at each pump at the beginning and at the end of the pipeline after the pump and before the pump, calculate the power acting on the pump shafts and their flow coefficients, measure the pressure drop across the pipeline using manometers and calculate the pressure drop using the formulas and, using the data obtained, diagnose and analyze the operation of the pump-pipe system gadfly for each controlled area (RF patent No. 2114325, IPC ⁷ F 04 D 13/06, publ. 06/27/98).

The application of the described methods allows to determine the presence of emergency situations on the pipeline, but does not allow to predict the moments of their occurrence, since these methods work in the presence of leaks.

Closest to the claimed method is a method for remote monitoring and diagnostics of the state of the structure and engineering structures, which consists in the fact that at the control point, signals are recorded from the measurement units installed in the places of diagnosis, they are compared with pre-recorded values, and the deviation of the received signals from in advance fixed judges of the presence of changes in controlled parameters (RF patent 2146810, IPC ⁷ G 01 M 5/00, G 08 C 17/02, publ. 20.03.00). Coded radio signals, each of which corresponds to the code of one of the measurement units, is formed at the control point, the measurement units are interrogated by coded radio signals, signals are received on the measurement units, the code of the measurement unit is compared with the code of the interrogation signal and, if they match, they transmit from the corresponding measurement unit to the control point of the signal carrying the measurement information, and its comparison with a pre-recorded value is performed at the control point.

The disadvantage of this method is the high error in assessing changes in the magnitude of the monitored parameters, arising due to the lack of information about the dependence of the output signals of the measurement units on the external impact on the monitored section of the pipeline structure as a whole, and the lack of information about the “zero” state of the structure, since in advance The fixed value of the output signals of the measurement units is taken to be a value that may not be such in a real pipeline.

To implement the method of monitoring and diagnosing the state of the structure and engineering structures, devices are needed.

A device for automatically diagnosing the state of construction (RF patent No. 2037798, IPC ⁷ G 01 M 3/18, publ. 06/19/95). It consists of pressure sensors at the ends of the pipeline in communication lines. The processing of signals in these lines is carried out by electronic logic units, the pressure change in the pipeline is continuously recorded using these signals, and the state of the pipeline is assessed by threshold values of these changes.

A disadvantage of the known device is that it is only an indicator of an emergency.

A device for remote monitoring the health of the cathodic protection station on trunk pipelines, which contains a pipeline as a communication channel, a matching unit and an information collection point containing a low-pass filter and an amplifier with indication (RF patent No. 2006953, IPC ⁷ G 08 C 19/02, publ. 30.01.94 g.). The source of the information signal in it is a generator made with an infralow pulsation frequency of negative polarity of a half-wave rectified voltage, connected by a signal wire to the negative terminal of the station and through the matching unit to an electromagnetic sensor, common to an autonomous anode ground electrode. The device contains series-connected interconnected selective filters connected to the pipeline, an amplifier with an indication and an earthing switch. The device can significantly increase the range and number of transmission of control signals.

The disadvantage of this device is that using this device you can evaluate only one parameter, which does not fully reflect the state of the structure.

Closest to the claimed device is a device for remote monitoring and diagnostics of the state of the structure, containing a control point, measuring units located in the places of diagnosis, transducers, a communication line, a controller (RF patent No. 2146810, IPC ⁷ G 01 M 5/00, G 08 C 17/02, publ. 20.03.00 g.). In the known device, the measurement units are mounted on the surface of the structure. The control point is made in the form of a computer with a printer, a serial interface unit connected to its input-output; connected in series to an encoder, modulator, radio transceiver, demodulator and decoder, the output of which is connected to the second input of the serial interface unit, the second output of which is connected to the input of the encoder. Each measurement unit is made in the form of a series-connected switch, a secondary horizon sensor power supply, an analog-to-digital converter, an encoder, a modulator, a radio transceiver, a demodulator, a decoder with a comparison circuit, the output of which is connected to the first input of the switch, to the second input of which an autonomous source is connected power supply, and the communication line is the radio link through the antenna of the radio transceiver.

This device has all the disadvantages of the method on which this device is based. In addition, when placing, attaching and protecting the measurement units on the surface of the pipeline, additional errors arise due to the presence of uncontrolled external influences on the pipeline.

The technical task is to create a way to obtain reliable, accurate and timely information about the state of the structure and engineering structures.

To solve the technical problem, it is proposed in the method of remote monitoring and diagnostics of the state of the structure and engineering structures, which consists in the fact that at the control point, signals are recorded from the measurement units installed in the places of diagnosis of the structure, they are compared with previously fixed values, and the deviation of the received signals from pre-recorded, they judge the presence of changes in the controlled parameters, make a structural element from the same material as the whole structure, place measurement units are carried out on it, metrological certification of the element with the measurement units placed on it is carried out by establishing dependencies between the signals from the measurement units and calibrated external influences, these dependencies are recorded on the control panel and used as pre-recorded signals, the element is inserted with the units installed on it measurements to the places of diagnosis of the structure, and the state is judged by the deviation of the received signals from the measurement units from pre-registered signals Design.

To implement the method, a device for remote monitoring and diagnostics of the state of the structure and engineering structures is used, containing a control point, measurement units located in the places of diagnosis of the structure, transducers, communication line, controller, and the measurement units are placed on a metrologically certified structural element made of the same material that the whole structure, and embedded in the places of diagnosis of the structure, while the structural element, with the measurement units placed on it, one with the appropriate units connected by their outputs to the controller input connected to a modem, which is through link its output connected to the control point.

In contrast to the prototype, the manufacture of a structural element from the same material as the whole structure, and the location of the measurement units on it and its subsequent metrological certification with the measurement units located on it by establishing the relationships between the signals from the measurement units and calibrated external influences, makes it possible to obtain reliable , more accurate data on changes occurring with the design and engineering structure. The data obtained during certification in the form of static characteristics are recorded in the controller and at the control and measuring station and, having installed the structural element on a potentially dangerous section of the structure, which after certification becomes a multichannel measuring device, the incoming signals are recorded, which are converted via converters, and compared with the initial obtained by certification by static characteristics, and having established the deviation, assess the state of operational characteristics a dangerous-area structure.

The drawing shows a block diagram of a device that implements a method for remote monitoring and diagnostics of the state of the structure and engineering structures.

The device consists of a structural element 1 made of the same material as the controlled section of the structure on which the measurement units are located:

- deformations 2, for example, tensoresistive, optoelectronic; mechanical stress 3, for example based on acoustic emission; vibration 4; pressure 5; expense 6; temperature of the transported product 7; soil temperature 8; electric current 9; electrical potential with a reference electrode 10.

The outputs of the measurement units 2–9 and 10 are connected to the inputs of the corresponding transducers 11–19, the inputs of which, in turn, are connected to the input of the controller 20. The output of the controller 20 is connected to a modem 21, which is connected via a communication line 22 to the input of a remote point control 23.

The method is carried out by the described device as follows (for example, a pipeline).

An encoded command signal with a code corresponding to a given measuring pipe, is supplied from a remote control point 23 via a communication line 22 through a modem 21 to the controller 20 and transfers it from standby to measurement mode. In this mode, analog signals from measuring units 2–9, and also, when measuring electric potential, directly from the pipe branch and reference electrode 10 are sent to the corresponding converters 11–19, where they are amplified and converted into digital signals. The signals from the converters are fed to the input of the controller 20, which is a microprocessor with a storage device that calculates and converts the information received from the converters. The calculation result is fed sequentially to the modem 21 and through the communication line 22 to the remote control point 23, where this result is compared with the data obtained during metrological certification and the technical condition of the pipeline is analyzed.

During metrological certification of the device, the determination of the static characteristics of the measurement units and the entire device as a whole is carried out according to GOST 8.508-84, according to which the static characteristics are determined with specified levels of accuracy and reliability in the form of polynomials from the given external influences. In this case, the following can act as external influences:

deformation under tension, compression, bending, torsion, vibration, temperature effects in a given temperature range.

A specific example of the use of the proposed method for remote monitoring and diagnostics of the state of the structure and engineering structures.

A pipe Dn = 720 mm δ = 8 mm, made of steel grade 17G1S and a length of 100 mm and made of a pipe with the same technical characteristics, is cut into the pipe Dn = 720 mm δ = 8 mm made of steel of 17G1S grade pipeline.

On the pipe set:

- strain gauge bridge sensors 1-LS31-6 / 350 (Germany), for measuring strain in three directions at one installation point (zero degrees, forty-five degrees, ninety degrees), combined into socket groups. Four outlets are located around the pipe at 90 °. The strain gage bridge sensor consists of four welded strain gages, of which two are measuring and two are thermal compensating. A total of forty-eight strain gages are used, forming twelve bridge sensors.

- Platinum thermometer TSP-0395 for measuring the temperature of the transported product.

- Long-term reference electrode ESN-MS2 for measuring the level of cathodic protection potential (the electrode is installed in the immediate vicinity of the nozzle). Data is transmitted from the reference electrode using a cable and connectors on the electronic unit.

After installing the sensors on the pipe, they are covered with covers. Covers equipped with cable glands provide sealing.

The temperature mode of operation of the device is from -10 to + 45 ° C.

Next, metrological certification of the pipe is carried out to establish the relationship between the signals from the sensors and the stress-strain state of the pipe from a known external influence.

Metrological certification of the pipe is carried out before its insertion into the pipeline.

When the pipe is loaded with internal pressure (pressure of the transported product), stresses will arise in the metal:

σ _about = (D _BH · P) / (4 · δ)

σ ₉₀ = (D _BH · P) / (2 · δ)

σ ₄₅ = (σ ₀ + σ ₉₀ ) / 2 + (σ ₀ -σ ₉₀ ) / 2)

where: σ - mechanical stresses in the direction of measurement of 0.45 and 90 degrees, MPa;

P is the pressure, MPa;

D _BH - inner diameter of the pipe, mm;

δ is the wall thickness, mm.

The supplied test pressure is monitored by a calibrated pressure gauge. The pressure is changed from zero to the desired value with a certain interval. Mechanical stresses on the load cells are converted into electrical signals, recorded in the block of secondary converters.

The obtained dependences Δ U = f (P), where Δ U are the signals of the unbalance of the load cells, P is the test pressure, according to the above ratios are recalculated in the dependence Δ U _i = f (σ _i ) After installation in the pipeline, using these dependencies, evaluate the real operational characteristics of the pipeline section.

An example of calculating pipeline deformations at internal pressures: 4.5 MPa and 5.4 MPa.

Initial data:

Pressure 4.5 MPa

Table 1 Outer diameter D _h 720 mm Wall thickness δ 8 mm Inner diameter D _bh 704 mm D _int = D _n -2 · δ Modulus of elasticity of steel E 2.1 · 10 ⁶ kgf / cm ² Poisson's ratio μ 0.3 steel grade 17G1S Yield strength σ _T 360 MPa

Stress calculation:

table 2 Longitudinal voltage σ ₀ 99 MPa σ ₀ = (Dвн · Р) / (4 · δ) Ring voltage σ ₉₀ 198 MPa σ ₉₀ = (Dвн · Р) / (2 · δ) Tension at an angle φ = 45 ° σ ₄₅ 148.5 MPa σ ₄₅ = (σ ₀ + σ ₉₀ ) / 2 + ((σ ₀ -σ ₉₀ ) / 2) cos2φ

Calculation of relative deformations:

Stress calculation:

Table 5 Longitudinal voltage σ ₀ 118.8 MPa σ ₀ = (Dвн · Р) / (4 · δ) Ring voltage σ ₉₀ 237.6 MPa σ ₉₀ = (Dвн · Р) / (2 · δ) Tension at an angle φ = 45 ° σ ₄₅ 111.4 MPa σ ₄₅ = (σ ₀ + σ ₉₀ ) / 2 +
((σ ₀ -σ ₉₀ ) / 2)

Calculation of relative deformations:

Table 6 Relative strain longitudinal design ε _{0 (p)} 2.3 · 10 ^-4 ε _{0 (r)} = σ ₀ / E-μ · σ ₉₀₎ / E Relative strain transverse calculated ε _{90 (p)} 9.6 · 10 ^-4 ε _{90 (p)} = σ ₉₀ / E- (μ σ ₀ ) / E Relative deformation At an angle φ = 45 ° calculated ε _{45 (p)} 5.9 · 10 ^-4 ε _{45 (p)} = (ε ₀ + ε ₉₀ ) / 2 +
((ε ₀ -ε ₉₀ ) / 2)

The data obtained during certification (see Table 1-6) and static characteristics are recorded in the controller.

A pipe with sensors installed on it, which after certification becomes a multi-channel measuring device, is installed on a potentially hazardous section of the pipeline, previously determined by the project, and the incoming signals are recorded, which are converted in the secondary transducer block, and compared with the initial ones (tables 1-6), obtained during certification, and by static characteristics, having established the deviation, assess the state of the operational characteristics of the pipeline section.

The proposed technical solution allows you to create a simple, reliable, operational tool for monitoring the condition of the pipeline during the entire time of its operation.

Claims (2)

1. The method of remote monitoring and diagnostics of the state of the structure and engineering structures, which consists in the fact that the control point records the signals from the measurement units installed in the places of diagnosis of the structure, compares them with pre-recorded values, and judges the deviation of the received signals from pre-recorded the presence of changes in the controlled parameters, characterized in that a structural element is made of the same material as the entire structure, the measurement units are placed on it, p they carry out metrological certification of the element with the measurement units placed on it by establishing dependencies between the signals from the measurement units and calibrated external influences, register these dependencies at the control point and use them as pre-recorded signals, insert the element with the measurement units installed on it into the diagnostic places of the structure , and judging by the deviation of the received signals from the measurement units from the previously registered signals, the state of the structure is judged. 2. The device for remote monitoring and diagnostics of the state of the structure and engineering structures in accordance with the method according to claim 1, containing a control point, measurement units located in the places of diagnosis of the structure, converters, communication line, controller, characterized in that the measurement units are placed metrologically certified structural member, made of the same material as the whole structure, and embedded in the diagnostic site of the structure, while the structural element, with blocks placed on it Measurements, connected to the respective units connected by their outputs to the controller input connected to a modem, which is through the communication line to its output connected to the control point.