Thanks to the new wireless telecommunication technologies, data access and visualization through Internet allow us to follow in real time the evolution of instrumented structures. This monitoring is essential during critical phases such as installation, production, maintenance or even when civil engineering works happens nearby.
For several years, Cementys uses and improves its supervisor software, called THMinsight, to display these indicators. These are necessary to control, monitor and alert about all the events which could damage an infrastructure. See below two new functionalities.
Geographical Information System
Our database server, set in Palaiseau (France), now integrates a GIS database, which is adapted to fit with a high demand of sensors, in urban projects. For example, thanks to this method, settled zones can be calculated and easily visualized.
Monitoring of railway infrastructures
This new functionality is adapted to the monitoring of railway structure geometry. In real time, it provides information about: levelling, pitching, the “gauche” and the slope of railways. These indicators are useful regarding the monitoring of the deformation of structures and ensure security of trains and their users.
Anticipating future energy challenges, Argentina asserts its will to increase its atomic energy industry. Argentina’s government has entrusted CNEA (Comisión Nacional de Energía Atómica) with the development of a new type of nuclear reactor, from low to medium electrical capacity, completely engineered and designed in Argentina.
The project, called CAREM 25, began in early 2014 at the Atucha nuclear site in the province of Buenos Aires.
CAREM 25 project
This new generation reactor, of reduced dimensions, will produce 25 MW which corresponds to the power supply of a 100 000 inhabitants city.
Cementys provides technical expertise to CNEA for the design and the implementation of a structural instrumentation and monitoring meeting the project’s requirements.
For this CAREM 25, Cementys favored to set-up a “long-term” instrumentation based on robust and viable Vibrating Wire sensors. These technology based sensors have been installed on French and worldwide nuclear power plants for more than 40 years and their reliability is no longer to be demonstrated.
In addition to so-called “traditional” sensors in the nuclear industry, CNEA has relied on Cementys’ fiber optic measurement technical expertise and know-how, to integrate optical fiber cable into several parts of the reactor’s slab and concrete walls.
“For such an ambitious project that is the CAREM 25, we desired to ensure a traditional structural monitoring (Vibrating Wire sensors), and improve it with an advanced technology that is optical fiber distributed measurement in order to better understand the behavior of the structure”, commented Vincent LAMOUR, technical director and civil engineering expert at Cementys.
Distributed measurement with optical fiber gives added-value data since temperature and strain perceived by the fiber optic cable is collected each meter over its entire length.
Slab’s instrumentation was installed during summer 2016, and allowed to verify the good behavior of the concrete during its pouring in October 2016. Optical fiber measurements emphasize the same temperatures and strains as recorded by the Vibrating Wire sensors, and moreover, provide many additional measuring data.
A dedicated web interface allows the CNEA Civil Engineering and Instrumentation engineers to visualize real time data from the various installed sensors.
Cementys’ engineering teams will continue to contribute to the coming phases of the project with their expertise, until the site’s commissioning in the first half of 2019.
Optical fiber: a revolution for pipeline leak detection
Pipeline leak detection is so important… Even though pipelines are still the safest way to transport oil and gas products, spills and leaks may occur. These incidents can have an important environmental impact, incur cleaning costs, and deteriorate the company’s image.
Several technologies have been developed to monitor the pipelines to detect or prevent leaks (ultrasounds, flow monitoring, smart pigs…). Optical fiber recently brought a revolution to the sector: we can now have a distributed measurement all along the line using telecommunication fibers, giving us every foot the temperature, strain and vibrations of the pipe.
Most optical leak detection systems today use Distributed Temperature Sensor (DTS) monitoring. When the product is at a different temperature than the exterior environment, a passive monitoring system will be able to rapidly detect leaks by looking for hot or cold spots along the line. This type of measurement has an extremely low false alarm level, especially if there is a big difference of temperature (LNG, heated oil, pressured gas with Joule Thomson effect…).
But when the product is at the same temperature than the exterior environment, a passive DTS monitoring will not work. This is why Cementys developed an Active DTS monitoring system: in this case, we use a metallic cable to heat the line, in order to analyze both the temperature and the temperature variation. This real time analysis gives out the thermal capacity of the environment, directly linked to the presence of oil.
For long lines, Cementys developed the Transient Monitoring System. To use an active DTS system, one will need power to heat the line (around 1W per meter). We can see that this solution is hard to implement for lines longer than a mile. Our Transient Monitoring System analyzes the temperature variations due to daily and seasonal changes. After a learning period, the system is capable to detect a change in behavior therefore a leak.
Thanks to those technologies, Cementys can help you to monitor all of your lines.
The GPR method uses radar propagation and reflection of electromagnetic waves of different frequencies.
A microwave antenna transmits pulses of very short duration in the soil or the structure, generally at frequencies ranging from 16MHz to 2.6 GHz (according to depth and resolution objectives). When the waves encounter a contact between two different dielectric permittivities environments, part of their energy is reflected, while the other goes deeper.
The acquisition system measures the travel time of the radar wave between its transmission and its reception. The depth is calculated using the travel time and the relative dielectric permittivity εr of the soil (v = c /√εr where c: speed of light and v: soil velocity).
However, this depth may be lower or even 0 if there is the presence of natural or artificial screens (clay soils, rebar mesh, metal plate, etc.).
During this GPR campaign, we used a 270MHz antenna that allows auscultation close to 6m deep.
The above radargram highlights anomalies, between 32 and 48 abscises, linked to voids extended between 3.5m and beyond 5.6m deep. GPR measures detect also geometric targets regularly spaced that appear to be related to wooden beams.
Distributed strain monitoring of structures using optical fiber sensing is a brand new technique which has opened new possibilities in tunnel survey. Cementys was mandated to install its SensoluxTM® sensor for two different structures: the brand new extension of the Parisian metro line 12 and the 35 years old Fréjus tunnel, the longest road tunnel in Europe, between France and Italy. The cable-sensor was set up on sensitive areas during important operations: a fire-access during tunnelling for RATP and underneath a fresh air gallery before the excavation for the SFTRF. The optical sensor is based on Raman (respectively Brillouin) backscattering to measure temperature (respectively deformation).
The cable-sensor detects the deformation over its whole length, without any blind spot, with a spatial resolution of 0.5m, a precision of ±5µdef and a range of several dozens of kilometres.
The small diameter of the sensor (2mm) makes it easy to integrate in tunnels by gluing the optical cable in grooves carved on the concrete. The optical cable is thus protected for long-term monitoring, without any maintenance of the measure system and with no deviation of the sensor. Moreover, the installation presents a low level of intrusiveness due to the fact that the cable is integrated into the concrete.
Any circumferential deformation of the structure is transmitted to the cable rings, cohesive to the concrete, and detected by the interrogators.
The first measure is considered as the baseline and the following measures are compared with the first one to track relative motions. Consequently, the initial stress of the cable due to gluing does not impact the measures.
The sensor measures the deformation (compression or expansion) of the concrete to detect local damages as cracks or global motion such as convergence phenomenon. Data is retrieved from a long distance with the optical fiber for real-time monitoring of the tunnel thanks to optical technologies.
Cementys developed a full range of solutions for the monitoring of cryogenic assets, from cool-down and leak detection monitoring of LNG tanks and pipelines to stress monitoring of liners and flexible FLNG pipes.
With operating temperatures as low as -200°C, optical fiber sensors are perfectly adapted for cryogenic applications, such as cool down monitoring and leak detection of LNG tanks and pipelines. Our qualified cable SensoLuxCRYO® can be implemented directly on the pipeline or base of the tank to be used as a Distributed Temperature Sensor, giving a measurement of temperature every meter: a leak corresponding to a cold spot will be immediately detected and localized, as it is recommended for spillage detection in the EN 1473:2007-06 european norm.
Being totally passive, SensoLuxCRYO® optical cable can safely be placed in the most explosive environments (ATEX zone 0 or Class 1 Div1 with low power lasers) and does not need any ATEX rated junction boxes, making optical fiber monitoring cost effective compared to traditional electric sensors (RTD). Optical fiber is also immune to electromagnetic noise or long cabling distance, giving out precise measurements miles away from the sensing part.
Our SensoLuxCRYO® solutions have been successfully implemented worldwide (Poland, France, Netherlands, India, USA).
Cementys team is proud to participate to the CAREM25 ongoing project in Argentina.
Vincent Lamour and Christian Medrano visited CNEA (Comisión Nacional de Energía Atómica) in Buenos Aeres this week and provided a professional training about Asset Integrity Monitoring of Nuclear Facilities.
CAREM25 project consists on the development, design and construction of a small nuclear power plant (25 MW SMR prototype).
Distributed strain sensor with optical fiber is a recent technology capable of measuring strain of offshore and onshore pipeline. A 3D layout of the fiber sensor on the all pipeline’s length is necessary to calculate global displacement of a specific portion or normal stress everywhere on its surface.
If production equipments and installations are capable of helical shape disposition around pipeline, only one optical fiber cable is necessary to measure what three optical fiber cables with straight disposition can measure.
Comparative experiment were made to compare performance of the well-known local Bragg sensor technology. Even though, strain resolution of Bragg grating (±1µdef) are better than Brillouin technology (±5µdef), distributed strain sensor gets its advantage on the number of equivalent sensor (1km of monitoring pipeline <=> 3000 local strain sensors). Ideal to cover very long pipeline (tens of kilometers).
Distributed measurements of strain and temperature by means of optical fiber: measurement of pipeline shape.
Cementys is proud to demonstrate its new distributed Strain and Temperature monitoring technologies based on Raman and Brillouin Optical Backscattered Time Domain Reflectometries.
Distributed strain and temperature allow to measure the displacement of a pipeline under flexion. To do so, Cementys needs at least 1 meter of fiber laid down either helicoidally or following 3 straight line at 120° around the pipe. To present both methods, two 13 meters long pipelines are respectively equipped with 3 straight fibers at 120 and with an helicoidal fiber.
2 different interrogation boxes are used, measuring different physical effects: one for the Brillouin effect (sensitive to temperature and strain) and the other for the Raman effect (sensitive only to temperature). By combining information, we can deduce the variation of strain due to mechanical stresses and the absolute temperature of the pipe, with a measurement every 50cm.
The experimental measurements of the amplitude and the direction of bending deflection are done real-time. Fiber optic being capable of long range measurements, remote locations can be interrogated (up to 40 miles).
The SensoluxTM® cable containing 4 tight buffered fibers (2 singlemode and 2 multimode) allows such measurements. Once attached to the pipeline with epoxy glue or equivalent adhesive, all the mechanical strains and temperature changes seen by the structure are fully transmitted to the optical fibers, and so detected by the interrogators.
Eventually, this instrumentation gives information on the mechanical strains all along the structure in real time.