NL1015354C2 - Composite gas or oil pipeline with embedded microchip and electrodes to detect corrosion and send data by radio signal to remote processor - Google Patents

Abstract

A microchip (6) in a composite steel and epoxy-resin pipe has four electrodes to detect corrosion. A microchip in each section of pipe is interrogated sequentially and its response transmitted, either by antenna or by the pipeline acting as a waveguide, to a remote processor. The pipe is formed of three or more steel layers (1,2) embedded in insulating layers (3,4) of epoxy resin. A microchip (6) is powered either by a long-life lithium-thionil battery (7) or by energy conducted along the pipe acting as a waveguide. It has four electrodes: two connected to the inner and outer steel layers; one (8) to the surrounding medium; and one (9) to the fluid in the pipe. The latter electrode is flush with the pipe wall to prevent turbulence. The microchip acts as a high impedance voltmeter.

Description

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A pipe containing a wireless device for detecting corrosion, a method for detecting corrosion in a pipe wirelessly and a method for producing the pain

The present invention relates to a pipe of the type made of one or more layers of steel embedded in an insulating reinforced material containing a wireless corrosion detection device. The invention also relates to a method for detecting corrosion on steel as a result of contact between the steel and a foreign electrolytic medium.

The pipes are generally used for gas or oil transportation, generally receiving high internal or external pressures. The internal pressures are those related to the transport of fluids, while the external pressures are due to weight of soil on the pipes when buried or hydrostatic pressures when immersed in water.

In general, pipes made in a conventional manner are capable of operating under the above pressures. However, steel is highly susceptible to corrosion. The fluids transported through the pipes and the external medium, especially soil where the pipes are buried, sea water when submerged, form corrosion electrolytes that can significantly damage the steel in a pipe and reduce its structural integrity and leak or cause oil spills 30, and very dangerous bursts may occur especially with pressurized gases.

To prevent this, steel pipes are coated with an insulating polymer material and / or also glass-reinforced polymer resins such as epoxy resin. US 1015354-2 Patent 4,351,364 describes pipes where the wall is formed by one or more superimposed layers of steel individually coated with epoxy resin and externally and internally coated with glass reinforced epoxy resin. According to this patent the construction is manufactured by using a mandrel on which initially glass reinforced epoxy resin is laid to a certain thickness, followed by laying one or more steel strips helically wound over the already placed glass reinforced resin. Finally, a glass-reinforced epoxy layer similar to the first layer, made of a certain thickness, prevents contact with the external medium.

Since an oil pipe or gas pipe made from arrays of such pipes is generally buried or immersed in water, it becomes difficult to perform visual inspection as to the condition of the individual pipes. In addition, in the case of the pipes of the above-mentioned patent, the corrosion damage of the steel layers 20 can only become apparent when it has passed through the insulating layers, thereby necessitating replacement of the pipe, probably causing an emergency.

Several corrosion detection systems have been proposed to detect corrosion on the steel layers of pipes made as described in the aforementioned patent. Patent 5529668 describes a method and apparatus for detecting a situation where one of the layers of steel comes into contact with the aforementioned corrosive media. Here it is described that the installation of external voltmeters with clamps connected to various connectors protruding from the external pipe casing. A first connector contacts the steel in the pipe and another is connected to an electrode in contact with the fluid transported in the pipes. Also, the second clamp of a voltmeter may be connected to an electrode in contact with the medium where the pipe is buried or immersed.

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Conclusions regarding the condition of the layers of steel in the pipes can be taken from the potential measured by the voltmeters.

This operative system has the drawback that the installation of such measuring instruments in exposed stations requires, also requiring long wiring, coming out of each pipe, usually 10 or 12 meters long, extending to a measuring station, meaning that for a pipeline stretching for several miles, thousands of feet of connector wires are required to converge to each of these stations.

The present invention tends to optimize monitoring of the integrity of the insulation of the layers of steel from the corrosive media, without the above drawbacks, with a measuring device capable of remote operation and no expensive or cumbersome wiring required .

Accordingly, it is the object of the present invention to provide a steel pipe covered with an insulating sheath containing in such an insulating sheath a wireless corrosion detector capable of transmitting the required distance information wirelessly.

The present invention includes a pipe made of one or more layers of steel embedded in an insulating material comprising an electronic device formed by a microchip embedded in the insulating layers, fed by an energy source and connected by one of its connectors to at least one layer of steel, and a second connector with a reference electrode or other conductive structure in contact with a conductive foreign medium, the foreign medium being selected from the fluid circulating in the pipes or an external medium surrounding the pipes . The microchip is capable of measuring electrical potential differences between at least one layer of steel and the conductive medium not belonging to the pipe. The microchip is capable of receiving the activation command and returning the information over a distance, wirelessly, to an appropriate instrument such as a data store.

Since these pipes are generally constructed of several layers of steel, according to a preferred embodiment of the invention a first clamp of the microchip is connected to the inner layer of steel, a second clamp is connected to the outer layer of steel and a third is connected to an electrical device placed in contact with the external medium such as water, or a structure that will provide sufficient grounding or also connected to a reference electrode which allows the measurement of the insulation of the layer of steel relative to the surrounding medium. A fourth connector is connected to an electrode 15 connected to the fluid circulating in the pipe so that the insulation state of the layer of steel of the fluid can be measured. Preferably, the electrode in contact with the fluid circulating in the pipe should be flush with the internal surface of the pipe to avoid unwanted turbulence.

When required at a distance, the microchip in a pipe will measure the electrical potential between the conductive medium surrounding the pipe and at least one of the layers of steel in the pipe, the microchip acting as a high impedance voltmeter (greater than 10 Megaohm), so that a polarization of the steel will not occur and will adversely affect the measurement.

It is expected that the danger of a contact or connection leading to corrosion of the outer layer of steel will come from the external medium surrounding the pipes and that the equivalent danger for the inner layer of steel will come from the medium circulating in the pipes, causing measurements can be made with respect to only the outer and inner layer of steel in the pipe with respect to the medium surrounding the pipes and the medium circulating in the pipes, respectively.

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Although composite steel pipes as described in US Patent 4,351,364 are taken as reference, it is to be understood that any other type of steel pipes with resin reinforced coating can be used for the installation of the detector of this invention. Similarly, the detector in the present invention can be applied to any pipe made of conductive materials embedded in non-conductive materials.

It is to be understood that the general terms "conductive materials" and "conductive medium" are used herein to refer to materials or media with a certain measure of electrical conductivity. Even a medium such as oil or petroleum can be sufficiently conductive and corrosive, especially since it can contain electrolytic material such as brine.

Depending on the type of pipes in the pipeline, the pipeline may act as a waveguide for the command and return signal of the information, or the microchip may be connected to an antenna that reaches the outer surface or even extends beyond the outer surface in cases where the pipes are buried underground or immersed in water. The antenna must be adequately insulated from the medium with an adequate polymer or other insulating material.

With this installation of each pipe in a pipeline (eg oil or gas line), a selective command signal is sent to each microchip, and a return signal from each microchip is received and collected at a distance in an adequate instrument such as a data store.

In such conditions, when one of the steel layers in a pipe contacts the external medium (or internal medium) due to lack of insulation caused by damage or defective material, the microchip will be able to measure a stable potential . Depending on the electrolysis process, this .101535 4-6 potential may be zero or assume any other value, but in both cases it will be constant over a period of time, in these cases indicating an error in the pipe corresponding to that microchip. Measurement time periods of between 2 to 5 seconds are sufficient to be considered critical.

On the other hand, if the insulation is intact, there is no connection between the external medium (or internal medium) in each layer of steel and the electrical circuit remains open and the electrical potential that could be measured and measured by the microchip will fluctuate.

In an analogous manner, it is possible to measure the stability or fluctuation of an electrical resistance 15, obtaining equal detection parameters taking into account the condition of the steel layer insulation and possible corrosion damage.

Optionally, the microchip could send unprocessed information that is later externally processed and analyzed or could send already processed information regarding the corrosion potential.

Energy required to power the microchip will be provided by a battery installed next to the microchip in a permanent manner as in the case of 25 lithium thonil type batteries, with a service life close to that of the pipeline or batteries installed in a special holder, in the pipe, with access to the battery so that it can be replaced when the battery has a limited life. The container should not interfere with the insulation of the layers of steel.

Another way to power the microchip in the pipes is through an activation signal that collects in a capacitor placed near the microchip 35 and connected to it. The command for the microchip to take the respective measurement can be added later or included in the activation signal.

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An additional form to provide external energy is by using the pipeline as a waveguide. In this case, the energy is supplied from the interior of the pipe.

The inclusion of the microchip and other components in a permanent manner could optionally be done during the manufacture of each pipe. This recording could be made in an area close to one end of the pipe, such as an area where there is a thicker reinforced resin layer. The procedure could be in accordance with the teachings of U.S. Pat. No. 4,351,364 already described above. The receptacle could also be made in the center part of the pipe so that it is equidistant from its ends. In this case, the microchip and other components will preferably be contained in a thicker layer of epoxy material reinforced with glass built up on the pipe.

Alternatively, the microchip may be included in one of the ends of the pipe already made. In this case, the operation could be opening one or more voids that are not through, where the pipe thickens in reinforced resin. Once the microchip is received in the cavity, and the electrode is exposed on the inner surface, the antenna and power means 25 are connected to the corresponding terminals in the microchip. The cavity or cavities are then sealed with epoxy material or other suitable insulating material.

In the event that, although less frequently, the pipes have only one layer of steel or pipe steel of each type, with insulating coating, the microchip will be bonded to that single layer of steel or pipe and refer to the external medium and medium for measurements circulating through the pipeline make the measurements in the same manner as already described.

In order to materialize the advantages already discussed and to better understand the constructive and functional features of the invention, a preferred embodiment described schematically is * 015354-8. The drawings are not to scale.

Figure 1 is a cross-sectional view of a pipe section consisting of two steel pipes containing a permanent energy source with a microchip connected to a ground lance and an electrode exposed to the internal circulating medium.

Figure 2 is an equivalent view to that shown in Figure 1, with the microchip attached to an antenna.

Figure 3 shows several pipes belonging to a pipeline with an antenna on a tower related to several microchips belonging to corresponding pipes.

As shown in Figure 1, the buried pipeline in this case is formed by one external (1) and one internal (2) steel pipe. Preferably three or more layers of steel form the core of this pipe type. Each layer of steel, or coiled steel, may be insulated with a layer of poly-20 resin (not shown) of the epoxy type. In order to protect the steel against the corrosion action of the external medium or of a medium circulating through the pipeline, the structure of the steel pipes or wound steel strips is surrounded by an external insulating layer (3) and an internal insulating (4), at preferably made of polymeric resin reinforced with fibers, such as glass fibers.

The steel pipes or wound strips do not necessarily extend to the ends (5) of each pipe in the pipeline. They can stop a short distance from each end. As a result, in this case there is no electrical continuity between each pipe in the pipeline.

A microchip (6) contained in the insulating material receives energy from a permanent battery (7), also contained in the insulating material. In an alternative embodiment, the power source for the microchip may be located in external access holders for a 101 Ras 4 - 9 replacement from the outside. Alternatively, the required energy can be supplied from the outside and over a distance, as will be explained later, or can be supplied by microwaves propagating through the inside of the pipe, the pipe acting as a waveguide.

The microchip (6) is connected to the steel pipes (1) and (2) and the ground lance (8) acts as an electrode of the surrounding medium and with the electrode (9) exposed on at least one of its surfaces to the fluid circulating through the pipeline.

With this structure, the microchip (6) is in the state for selectively measuring the potential difference between the steel pipes or wound strips and the ground lance (8) and between the steel pipes or steel wound strips and the electrode (9).

Although it is possible to make crossed measurements, which is between external steel strip and internal medium and internal steel strip and external medium, this does not seem to be useful and the preferred measurements are between (1) and (8) and between (2) and (9), since it is expected that the danger of a corrosion promoting contact from the external steel wound strip or pipe will come only from the external medium and that from the internally wound steel strip or pipe will come from the medium circulating through the pipeline.

It has been found that in pipes such as those described in U.S. Patent 4,351,364, the resin does not uniformly isolate the wound steel strips and contacts may exist between the steel layers. In such cases, the measurement for both steel strips, internal and external (and / or if present intermediate strips), is made as if there were a single steel strip without the possibility of distinction.

Alternatively, the microchip can be connected to a conductive pipe base buried acting as a ground or to a reference electrode.

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According to another embodiment of the invention, in the case of the pipeline immersed in water, the microchip is connected to an electrode immersed in the body of water, optionally held by a float.

Figure 2 shows the microchip (6) attached to an antenna (10) that may be just below the ground (or water) or protrude from the ground (or water), thus receiving and emitting signals between the microchip and 10 optimizing the instrument used as an external command. This antenna (10) should be adequately insulated from the external medium to prevent any corrosion.

Figure 3 shows several pipes in a pipeline 15 with their microchips (6) arranged to receive the command and transmit the information to an antenna on a tower (11). The antenna will send the signal again directly or by satellite to an operating center.

As explained above, the energy required by the microchip can be provided by batteries installed next to the microchip as shown in Figures 1 and 2. Depending on the energy consumption in each measurement and the frequency of measurements, the batteries may be active for the duration of the useful life of the pipeline as in the case of lithium tonil batteries. Alternatively, the batteries can be placed in each pipe so that they can be replaced when necessary.

According to even another embodiment, the micro chip (6) can be activated from the outside and over a distance. The energy stored in an activation signal can be collected in a capacitor near the microchip.

In another alternative, the pipeline 35 acts as a waveguide capable of transporting the energy required to feed each microchip in the pipeline. This is possible, especially for pipelines 1 01 5354 - 11 - buried underground or submerged, due to the large dielectric discontinuity existing between the gas / pipe (for a gas line) system and gas / earth or gas water; the latter is a dielectric with losses. The 5 frequencies used for the pipelines about 0.5 m in diameter will be several hundred Megahertz; preferably a frequency above the cut-off frequency and below the second propagation mode should be selected.

An adequate microchip that can be used in the present invention is constituted by the following blocks which are adequately connected. Based on the state of the art in microelectronics, these blocks and the microchip are perfectly feasible.

External signal acquisition block.

15 Potential measuring block.

Measurement data storage block; after measurements, this block processes the data and sends it out or can send it directly unprocessed depending on the commands of the control block.

20 Processing block. Evaluates results of the measurements made, controlling the measurement time, gives an alarm signal regarding corrosion detected by the measurement.

External signal receiving block.

25 Measurement result transmission block. Sends the information in the measurements.

Rule and comparison block; this interprets and executes the received commands.

The activation signal and command commands for the measurements as well as the response signal sent by each microchip can be emitted and received respectively by an operator driving close to the pipeline with a vehicle and the appropriate equipment or by means of antennas of the aforementioned type and described in figure 3.

Alternatively and depending on the characteristics of the pipes, the pipeline can act as a waveguide 1015354-12 - which commands each microchip by means of a signal with frequency depending on the diameter of the pipes. For example, for a 0.5 meter diameter pipe, the frequency is close to several hundred Megahertz, which is 5 between the VHF and UHF frequencies. The connection to the microchip can be the receiving antenna, and this antenna can be a flat antenna (patch type) held on the inner wall of the pipe and a diode detector. The energy detected by the antenna and rectified by the diode 10 can be used to simultaneously power, optionally, the microchip and also "wake up" the microchip and interrogate it. The microchip will then transmit the response signal, also through the pipeline, to a receiver that is part of the microwave-15 transceptor.

Finally, the electrical potential measurement will provide an indication of whether the steel is in contact with the external or internal medium or not. A stable potential shows that there is a contact and a risk of corrosion. It should be understood that an electrical potential is stable and shows traces of corrosion when the variation is less than 0.01 mV over a predetermined length of time. The recommended predetermined length of time is 10 seconds or even less with 1 second being sufficient and 2 to 5 seconds being typical time measurements.

In contrast, if there is no contact between the external medium (or interior) and the corresponding steel strip or pipe, the circuit will be open and the electrical potential measured by the microchip may fluctuate or be unstable. A measurement showing a variation of more than 0.03 mV and up to 100 mV during the initial 5 seconds of the measurement is considered to be unstable, thus indicating that there is no risk of corrosion.

35 Once a stable potential is detected by one of the microchips in the pipeline, and the corresponding information is sent and received 1 η λ 4 - 13 -, the corresponding pipe can be inspected at a greater frequency and eventually its replacement can be be programmed.

The measurements received by type 5 antennas described in Figure 3 can be sent to a centralizing station. The signals from each microchip contain the identification of the corresponding pipe.

Although the measurement of a stable potential in one of the pipes by a microchip indicates a corrosion hazard, the pipes described in U.S. Pat. No. 4,451,364 are designed to allow relatively long operation after the onset of corrosion. This time can be about 1 year before there is a serious risk of leakage or malfunction. The measurements made by the device of the present invention, at intervals less than 1 year, will allow programming of the replacement of the affected pipes before failure occurs.

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Claims (20)

1. A pipe containing a wireless device for detecting the possible occurrence of corrosion, the pipe being formed by one or more concentric layers of steel embedded in insulating reinforced material, characterized in that a microchip is fed by a energy source is included in the insulating layer, the microchip being connected by one of its connector clips to at least one of the layers of steel and connected by at least one other connector clip to an electrode or other conductive structure exposed to a medium other than the pipe, the medium being selected from the medium circulating in the pipe or the medium surrounding the pipe, the microchip being able to measure an electric potential difference or resistance between the at least one layer of steel and the other medium, and wherein the microchip is capable of receiving the activation command and wirelessly v sending the information by means of a remote signal to a suitable instrument. A pipe according to claim 1, wherein the microchip is connected by one of its connector clamps to a layer of steel close to the inner insulating sheath and by another connector clamp to an electrode exposed to the medium circulating in the pipe being the microchip in is capable of measuring the electrical potential differences or electrical resistance between the layer of steel and the medium circulating in the pipe. The pipe of claim 1, wherein the microchip 30 is connected by one of its connector clips to the layer of steel close to the outer insulating sheath and by another connector clip to an electrode exposed to the medium surrounding the pipe being capable of the microchip. 0l 535 A '*> - 15 - to measure electrical potential differences or electrical resistance between the layer of steel and the surrounding medium. Pipe according to any one of the preceding claims, wherein the microchip is connected to an antenna that reaches or even protrudes above the buried pipe. A pipe according to any one of claims 1 to 3, wherein the energy source for powering the microchip includes a permanent battery contained in the insulating coating. Pipe according to any one of claims 1 to 3, wherein the energy source for powering the microchip contains a replaceable battery installed in an insulated container accessible from the outside. The pipe of any one of claims 1 to 3, wherein the power source for powering the microchip transmitted wirelessly from a distance is stored in a capacitor connected to the microchip. 2 0 8. Method for wirelessly detecting the possible occurrence of corrosion in a pipe belonging to a pipeline, the pipe being formed by one or more concentric layers of steel embedded in insulating reinforced material containing a wireless device, incorporated in the insulating reinforced coating, the device consisting of a microchip connected by one of its connector clips to at least one layer of steel and connected by at least a second connector clip to an electrode exposed to a medium other than the pipe, wherein the method includes the steps from: - sending a wireless signal to the microchip in the form of a command; - measuring an electric potential or electrical resistance between at least one layer of steel and a conductive medium other than the pipe during a certain period of time; 1 0 1 53 5 4 * 1 - 16 - - determining whether the electrical potential or electrical resistance measured is stable or fluctuates over a period of time; - receiving the information transmitted by the microchip remotely in a wireless manner. The method of claim 8, wherein the signals are emitted and received from the microchip by means of an electromagnetic wave antenna on a tower erected near the pipeline. The method of claim 8, wherein the signals are sent to and received by the microchip using the pipeline as a waveguide. 11. The method of claim 10, wherein the connection to the microchip may have a planar antenna attached to the inner surface of the pipe and a diode detector. A method of manufacturing a pipe comprising a wireless corrosion detection device 2, wherein the pipe of the type is formed by one or more concentric layers of steel embedded in an insulating reinforced material, the method includes steps of: - incorporating an electrode into the insulating material during the manufacturing process of the pipe with one of its planes equal to the internal surface of the pipe; - optionally receiving, attached to the inner surface of the pipe, a planar antenna and a diode detector; - recording a microchip capable of measuring electrical potential differences or electrical resistance and also capable of receiving the activation command and remotely returning information by a wireless signal; - providing the connections between the connector terminals of the microchip and at least one layer of 1015354 '- 17 steel, the electrode being equal to the internal surface of the pipe and the antenna; - providing the connection between another connector clip of the microchip protruding beyond the outer surface of the pipe, and an electrode external to the pipe. 13. A method of manufacturing a pipe comprising a wireless corrosion detection device, the pipe of the type being formed by one or more concentric layers of steel embedded in an insulating reinforced material, the method comprising the steps comprising: - incorporating an electrode 15 in the insulating material during the manufacturing process of the pipe with one of its surfaces equal to the internal surface of the pipe; - optionally receiving, attached to the inner surface of the pipe, a planar antenna and a diode detector; 20. complete the manufacture of the pipe until its termination; - making at least one cavity in the insulating material of the finished pipe; - inserting a microchip into the cavity capable of measuring electrical potential or electrical resistance differences and capable of receiving the activation command and returning information thereon remotely by a wireless signal; - inserting the connections between the microchip and at least one layer of steel or wound steel strip, between the microchip and the internal electrode, between the microchip and the antenna and providing a connector attached to one of the connector terminals of the microchip protruding beyond the external surface 35 of the pipe; - sealing the room or areas with sufficient insulating material. 1 01 5354 "! - 18 - 14. A method of manufacturing a pipe comprising a wireless corrosion detection device, the pipe of the type being formed by one or more concentric layers of steel 5 embedded in an insulating reinforced material, the method comprising the steps includes: - drilling at least one cavity into the insulating material of a finished pipe; - incorporating a microchip into the cavity capable of measuring electrical potential or electrical resistance differences and capable of receiving an activation command and returning information thereon remotely by a wireless signal; optionally incorporating into the cavity a receiving electrode with one of its faces exposed and equal to the interior surface of the pipe; optionally occupying a planar antenna and diode detector in the cavity; inserting the connections between the microchip and at least one layer of steel, between the microchip and the internal electrode, between the microchip and the antenna and providing a connector attached to one of the microchip's connector terminals extending beyond the exterior surface of the pipe; 25. sealing the cavity or cavities with sufficiently insulating material. A method according to any one of claims 12 to 14 comprising the steps of: - connecting one of the connector clips 30 of the microchip to the outer layer of steel or wound steel strip; - connecting a second connector clamp of the microchip to an electrode equal to the internal pipe surface. The method of any one of claims 12 to 14, comprising the steps of: 1015354-19 - connecting one of the microchip connector terminals to the outer layer of steel or wound steel strip; - connecting a second connector clip of the microchip to a connector member protruding beyond the outer surface of the pipe capable of being connected to an electrode external to the pipe. A method according to any one of claims 12 to 14, wherein the microchip is taken up in an area of the pipe which is thicker in the resin reinforced material, the area being placed in one end of the pipe. 18. A method according to any one of claims 12 to 14, wherein the microchip is taken up in an area where the reinforced resin material is thickened, the area being placed in the center of the pipe. 19. A method according to any one of claims 12 to 18, wherein the microchip connector clamp is connected to a connector protruding beyond the outer surface of the pipe to which an external antenna is further connected. 20. A method according to any one of claims 12 to 19, wherein an energy source for the microchip is wholly or partly incorporated in the insulating material. -o-o-o- 1015354