RU2294482C1 - Mode of control and detection of defects in pipelines out of ferromagnetic materials - Google Patents

Abstract

FIELD: the invention refers to the field of control and detection of defects in pipelines out of ferromagnetic materials.

SUBSTANCE: the mode measures the absolute value of the module of magnetic induction or/and the gradient of the value of the module of magnetic induction, builds the graph of dependence of the value of the module of magnetic induction or/and the gradient of the value of the module of magnetic induction from distance, finds middle values of magnitudes of magnetic induction and/or the gradient of the value of the module of magnetic induction for selected plot, defines the value of mean square deviations and select the fields where values of the meanings of the module of the induction of a magnetic field and/or the gradient of the value of mean square deviations. After that plots on the terrain are defined correspondently separated on the graph of the fields and execute control of the pipeline by indestructible methods.

EFFECT: prevents gusts and in time repair of potentially dangerous plots(possibility of forecasting of possible breaks).

3 cl, 1 dwg

Description

The present invention relates to the field of non-destructive testing of pipeline transport and can be used to detect defects in pipelines used in reservoir pressure maintenance systems, field oil and gas gathering, product pipelines, gas distribution networks of settlements, gas and oil pipelines, in water supply and sewage systems housing and communal services, chemical production pipelines.

The well-known "Method of monitoring the state of the main pipeline" (RF patent 2174645 C2, IPC F 17 D 5/02, Publ. 10.10.2001, BI No. 28), which consists in continuous visual inspection of the surface of the route of the main pipeline using a stationary thermal imaging equipment, including thermal imaging cameras and radio transmitters installed on the supports of the overhead power line of the cathodic protection of the pipeline being built along the route, as well as radio, computing, video monitoring and printing devices, are installed at the next upward movement of the transported product transfer station, where at the request of the operator, and when a leak automatically in real time on the screen deployed monitor device thermal image fields, and using the printing apparatus documented digital information inspection area.

The specified method is not applicable in the absence of cathodic protection of pipelines, it is not able to provide information in the absence of temperature gradients, in particular in pipelines to maintain reservoir pressure.

Also known is the "Method of in-line diagnostics" (RF patent 2169308 C1 F 17 D 5/02 Publ. June 20, 2001 BI No. 17), including the determination of defects by the ultrasonic method, the determination of defects by the method of magnetic expiration, the combination and addition of research results in the analysis process According to the invention, the obtained data additionally investigates the walls of the pipeline by the magneto-optical method, the results of which are combined with the results of measurements by the ultrasonic method and the magnetic outflow method. The invention improves the reliability of in-line diagnostics by increasing the accuracy of determining the crack length and the ability to diagnose spider and multichannel corrosion and long-term fatigue cracking.

However, this method involves contact measurement using an in-tube projectile, which is not always possible and advisable (due to the large amount of preparatory work and, accordingly, the high cost, and is applicable only to specially equipped pipelines).

Closest to the technical nature of the claimed is the "Method for predicting leaks in pipelines" (RF patent 2062394 C1 F 17 D 5/02, Publ. BI No. 17.06.06.06), which consists in measuring the gradient of the horizontal component of the intrinsic magnetic intensity over the pipeline field pipeline α, oriented along its axis, and the ratio of vertical and horizontal components of the magnetic field β. Principle: measure the modules of the characteristic parameters of the pipelines, compare their changes at the boundaries of discrete sections and determine the location of the predicted leak in the pipeline using the maximum gradient modulus, and determine the type and size of the defect by modulating the ratios of the components of the intrinsic magnetic field strength of the pipeline.

Common features of the claimed invention and the closest analogue are the control and detection of defects in pipelines of ferromagnetic materials.

The disadvantages of this method are that it is applicable for the study of the near field, which means that at least the contact of the sensor with the surface and at the very least a slight removal are assumed. Using this method, the location of the predicted leak is determined, while the main task is to identify defects that are at different stages of development.

The technical task of the invention is to increase the efficiency of defect detection, their ranking according to the degree of danger and determining the state of the pipeline body in a non-contact way, reducing the complexity (there is no need to use additional equipment, there is no need to access the pipe body).

The technical problem is solved by measuring the absolute value of the magnetic induction module, measured in T (Tesla) and / or the gradient of the magnitude of the magnetic induction module, measured in T (Tesla), plotting the magnitude of the magnetic induction module and / or the gradient of the magnitude of the magnetic induction on distance, finding the average values of the magnitude of the magnetic induction and / or the gradient of the magnitude of the magnetic induction module for the selected area, determining the magnitude of the standard deviations and highlighting the area where the values values of the magnetic field induction module and / or gradient, the magnitudes of the magnetic induction module are equal to or double the value of the standard deviations, and then the areas corresponding to the areas highlighted on the graph are determined on the ground, and the pipeline is monitored in these places by non-destructive methods.

It is preferable if in the method the average values of the magnetic induction module and / or the gradient of the magnetic induction module are determined for sections of the pipeline with the same distance between the sensor and the axis of the pipeline (in the case of underground or underwater execution, the depth, i.e. the pipeline is laid at approximately the same depth). The spread in the position of the axis of the pipeline from the “constant” can be ± 0.5 m. The distance from the sensor to the axis of the pipeline is governed only by the sensitivity of the system (equipment) used for measurements.

The magnitude of the magnetic induction module and / or the gradient of the magnetic induction module is measured with a resolution of 0.25-0.5 m, and, if necessary, more often.

The main factors leading to a decrease in the reliability of pipelines are:

1) corrosion damage to the outer surfaces of pipelines due to insulation failure;

2) erosion damage to the internal surfaces of pipelines due to intergranular corrosion and hydrodynamic shock of the transported product, leading to the loss of metal in the pipe wall;

3) defects in welding operations.

Under certain conditions, these factors can lead to cracking and rupture of the metal.

It is known that a defect in a pipe is a stress concentrator. Stresses of this kind on a ferromagnetic material lead to additional magnetization in the region of the defect.

The method is implemented as follows.

On the ground along the pipeline, the magnetic induction and / or the magnetic induction gradient are measured with a resolution (increment) of 0.25-0.5 m (and, if necessary, more often). For measurements, instruments can be used that register the magnetic induction module and / or the gradient of the magnetic induction module of the magnetic field. For example: quantum, proton (including those based on the Overhauser effect), magnetoresistive magnetometers, and magnetometers based on the Zeeman effect.

During measurements along the pipeline, a graph of the dependence of the magnitude of the magnetic induction module and / or the gradient of the magnetic induction module on the distance is obtained and the average values of the magnitude of the magnetic induction module and / or gradient of the magnetic induction module are found for the selected section with the same distance between the sensor and the axis of the pipeline.

Then, the values of standard deviations are determined and the regions where the values of the magnetic field modulus and / or the gradient of the magnetic induction modulus are equal to or greater than twice the value of the standard deviations are determined.

The measured value beyond the "average plus / minus two standard deviations of the measured value" limits is an indication of the transition of the technical system (in our case, the pipeline) to an emergency state.

The areas highlighted on the graph are determined on the ground, and non-destructive testing of the pipeline is carried out in these areas. As a rule, either defects or areas that represent a potential threat of defects are noted in these areas.

The essence of the method is illustrated using the drawing on a specific example.

Concrete example

The measurements were carried out on an oil pipeline at one of the fields of OAO Tatneft. The measurements were carried out with an MM-60 step magnetometer, the measurement step was 0.25 m. After processing the measurements in the field using a laptop computer (laptop (results are shown in the drawing), holes were drilled at points 1 and 2. At point 1, a weld was detected no visible defects. At point No. 1, an X-ray inspection of the detected weld was performed. X-ray control showed the presence of lack of penetration in the root of the seam with a length of 250 mm and a width of 1-1.5 mm, which does not meet the requirements of BCH 012-88. At point 2, a micro-rupture was detected (pumped liquid outflowed from a corrosion ulcer in the pipeline body); 3 - values of standard deviations; 4 - average values of magnetic induction.

The proposed method for detecting defects is non-contact, non-destructive, does not require earthworks during measurement, reduces labor costs for performing measurements (two people perform the work), has the prospect of a high level of automation, allows you to document measurement results, build a database on which to build a system of continuity of the walls of the pipeline and quality control of installation works. The method is applicable to the entire range of pipelines made of ferromagnetic materials and using ferromagnetic materials (for example, plastic pipes).

This method of monitoring and detecting defects in pipelines made of ferromagnetic materials allows measurements in the surface, underground, surface and underwater versions of pipelines with the appropriate equipment.

Claims (3)

1. A method for monitoring and detecting defects in pipelines made of ferromagnetic materials, characterized in that they measure the magnitude of the magnetic induction module and / or the gradient of the magnetic induction module, build a graph of the dependence of the magnitude of the magnetic induction and / or gradient of the magnetic induction module on the distance and find the average values the mentioned values of magnetic induction for the selected area and determine the corresponding values of standard deviations, then highlight on the graph the area where the values of the mentioned values Ichin magnetic induction equal to or greater than the corresponding values of the doubled standard deviations, after which the areas on portions corresponding to selected areas on the chart and at these locations monitor pipeline. 2. The method according to claim 1, characterized in that the average values of the magnetic induction module and / or gradient of the magnetic induction module are determined for sections of the pipeline with the same distance between the sensor and the axis of the pipeline. 3. The method according to claim 1, characterized in that the magnitude of the magnetic induction module or gradient of the magnetic induction module is measured with a resolution of 0.25-0.5 m