Multi Channel Electronic Calipers PVM
Caliper pig is an in-line tool which moves inside a pipeline and gathers information about internal surface and geometry of the pipeline as well as distribution of pressure and temperature along the pipeline. Usually calipers are used to check if other inspection or utility in-line pig can pass through this pipeline without damage.
The shape of the pipeline internal cross-section is determined every few millimeters of the distance using the system of independently suspended spring loaded measuring arms. Each arm is in the contact with internal surface of the pipeline. Distance is measured by several odometric wheels. Calipers PVM also have navigation modulus which registers with high accuracy angular velocities and accelerations.
The information from sensors about internal cross-section, velocity, accelerations, angular velocities, pressure and temperature is stored in the internal memory of the caliper during run through a pipeline. After the run this raw information is copied to a computer for visualization and analysis in special computer program of geometry defects, bends, valves, T-joints, etc. Then a report is usually prepared together with pipeline log file. Thanks to navigation modulus in each PVM caliper it is possible to calculate trajectory of the pipeline and GPS coordinates for each peculiarity.
APRODIT LLC has been developing and manufacturing in-line electronic calipers since 2006. Over the years of operations our calipers have traveled many hundred kilometers in various conditions in short inter-field multi-phase pipelines and in long trunk oil and gas pipelines also in different water pipelines.
Our goal is to propose the calipers that meet the expectations of our customers which want to have for each diameter easy-to-use and inexpensive but reliable tool, with minimum weight and minimum length. It should be possible to launch the caliper through already installed launching / receiving chambers without any lengthening or changing design of these chambers. Or even to launch the tool via simplified temporarily mounted chambers.
Caliper pig run through a pipeline should be performed without changing pressure or velocity of pumping. It should also be possible to inspect yet empty pipelines at the stage of pipeline commissioning after its construction. For example at the stage of hydrotesting or even just after the last circumferential weld of the pipeline section.
In case there is Internet connection then raw data file from caliper can be transfered to our company specialists. Data file is typicaly 0.5 - 2 Gb and 3-4 times smaller after zip compression. Our specialists can be involved in work for report preparations. The data analysis can also be made in-situ by Operator' specialists as far as we provide the software with the tool and can propose short training also.
Our advantages
All calipers PVM manufactured by APRODIT can pass pipeline 90 degrees back-to-back bends with minimum radius R = 1.5 D.
Modular principle is applied in the mechanical design and electronics of PVM calipers. This means the possibility of easy replacement (combination) of individual modules: towing section, measuring section and odometers. This principle reduces the cost of the tool and provides the ability to adapt the caliper to specific conditions even in the field conditions. Including reconfiguration to other diameters. Or changing towing section adopted for liquid to one adopted for gas media.
Using the lever measuring system of the caliper, consisting of 8 or 16 independent levers (arms), the cross-sectional shape of the pipeline is determined every 5-8 mm of the distance traveled.
Calipers PVM can determine and visualize: dents and corrugations, factory-made bends, protrusion of welds, geometry of valves and other features of the pipeline. The recorded data of the caliper are displayed in user friendly form and can be sorted according to filters set by a user, for example, by maximum narrowing. Caliper data are the direct measurements. It is clear clear how they were obtained. And it is easy to verify them.
The odometer system of the caliper has several high-precision independent odometers. Odometers have original design and special circuitry solutions. It allows to "tie" a feature of the pipeline at a distance from the launching chamber (or a marker point with known GPS coordinates) with an error not more than 1%.
The recorded data is displayed in a user-friendly way. A pipeline log of various features and defects is compiled. Its filling is as automated as possible.
A variety of filters are available to sort the displayed features according to a user-selected criterion, such as maximum narrowing.
All calipers PVM are equipped with a high-precision navigation module, thanks to which all bends of the pipeline are reliably measured and visualized. Accurate measurement of the parameters of all bends (angle, bend radius, direction) and their automatic fixation in the pipeline log are used to build the pipeline trajectory.
This process is called xyz-mapping.
At the beginning of this process, the user sets the GPS coordinates of several reference (marker) points located along the pipeline route. Further, the program automatically calculates the coordinates for all other features present in the pipeline log.
As a result, the user receives the trajectory of the pipeline and the coordinates of all features with a sufficiently high accuracy. Then, by exporting a kml-file from the PVM data Analysis program, the user receives a pipeline layout, which shows all the features from the pipeline log (geometry defects, bends, valves, etc.). All this is now available in a convenient form on an electronic map of the area in a geographic information program like Google Earth or any other electronic map where kml files can be imported.
The operating environment of calipers is liquid, gaseous and multiphase media, including explosive ones. Run of PVM caliper can be performed in existing oil and gas pipelines without changing the pumping mode. Operating pressure range - up to 120 atm, speed of motion - up to 10 m/s.
Calipers PVM are certified in accordance with the technical requirements of the Customs Union TR CU 012/2011 "On the safety of equipment for work in explosive environments".
The list of International Electrical Commission (IEC) standards applied on a voluntary basis to ensure the compliance with the TR CU 012/2011 certificate is the following:
IEC 60079 0:2011 Explosive atmospheres. Part 0. Equipment. General requirements.
IEC 60079 11:2011 Explosive atmospheres. Part 11. Equipment with type of protection "Intrinsically safe electrical circuit «i».
IEC 60079-14-2013 Explosive atmospheres. Part 14. Design, selection and assembly of electrical installations.
Each PVM caliper is necessarily equipped with a certified PNT low-frequency transmitter of the appropriate size. The signals from the transmitter are received by low-frequency receivers NPR at the marker points located along the pipeline route. If necessary, this technology of temporary marking allows to get a reference in the distance from the detected anomaly to the two nearest marker points, also with an error of not more than 1%. In addition, the transmitter signal is used to accompany the caliper along the pipeline, as well as to search for it in the event of an abnormal stop.
The risk of PVM caliper getting stuck is minimal due to the fact that a standard SKT gauging pig with increased passing ability and with an installed transmitter is used as the towing section. To the gauging pig only a gimbal is added to connect to the measuring section. The gauging pig is always run first through the pipeline. And the passability of the trailed measuring section of the caliper and odometers for each diameter is chosen better than that of the towing section. This is the guarantee that the PVM caliper will not get stuck in the pipeline, where the SKT gauging pig has already been run.
The software is included in the delivery set together with the PVM caliper. The computer program for processing and visualizing the recorded data has an intuitive interface and graphics. The program has several automatic and semi-automatic procedures and filters that greatly facilitate the work with large amounts of data. There is also a block for automatic preparation of express reports.
Thanks to this, it is possible to prepare an express report with a list of all the identified features and defects, with their reference in distance to the nearest circumferential welds or bends, in a few hours. This software has been "perfected" by our programmers for over 10 years while processing the data of caliper runs through all kinds of pipelines. At the same time, our goal was to create a simple, intuitive system focused on fast progress by any new user. No special knowledge or special computers is required to work with the programs. Everything works on a regular office computer with Windows operating system.
Calipers PVM are delivered in strong plastic box or boxes convenient for long distance transportation and storage. Replacement parts of different diameters according to the customer request are usually included to the delivery set.
Modifications
Electronic calipers PVM are a new development of APRODIT LLC. Electronic caliper PIGs PVM-3 and PVM-4 are distinguished by several times lower power consumption with consistently high accuracy and reliability. Due to the reduced power consumption, these calipers can operate several days from 2 AA lithium batteries or 1 D lithium battery. This made it possible to radically reduce the size of the measuring section and thereby significantly increase the throughput of these calipers.
Electronic calipers of the PVM-3 and PVM-4 series were designed for pipelines 4", 6", 8", 10" and 12". They can be manufactured and delivered within few months. For other diameters up to 24", it is possible to manufacture custom-made measuring systems and assemble caliper on the basis of a modular principle.
We have been improving calipers for over 15 years. And since the development of microelectronics does not stand still, we are constantly looking for new solutions. The introduction of new electronic components allows us to reduce the size and weight of the housing - the main element of the measuring section of the caliper. And it in turn determines all other dimensions and characteristics of the caliper.
Also, thanks to the implemented navigation modules and data analysis algorithms, calipers PVM-3-8 and PVM-4-16 have very wide capabilities not only in the scope of geometry inspections of pipelines and search of various narrowings, but also for calculating of pipeline trajectory and plotting it on an electronic maps of the terrain in form of kml files. The integration of images made from space into algorithm of caliper data analysis allow to encrease accuracy and reliability of the information.
Special possibilities
The increased number of measuring channels (levers) in the PVM Series Profilers can be implemented (on special order) by connecting several measuring sections in series with a slight angular displacement of the rear section levers relative to the front section levers. This ensures complete overlap by the measuring levers of the inner surface of the pipeline.
Form-measuring (Geometry Inspection) PVM Series PIGs are the lightest of any inline Profiler for the same diameter. For running with compressed air or other gas through the newly built pipelines, special towing sections are designed to the open end. Due to their ultra-light weight and special high-flotation sealing system, it is possible to reduce uneven movement (jerking) when the Profiler is moved inside the pipeline under the influence of compressed gas.
By drastically reducing the maximum (peak) travel speed when moving in a gas environment with low pressure, the likelihood of damage to both the pipeline and the Profiler during such runs is also minimized.
A conventional mobile air compressor can be used to move the Profiler PVM inside an unfilled pipeline, and its capacity must be sufficient to replace the entire internal volume of the pipeline in a few hours. These Profiler PVM runs with a special pull section can be performed prior to hydrotesting of the pipeline being commissioned.
The standard Profiler PVM pull section, which is usually equipped with 4 polyurethane sleeves or discs, is used for pipeline inspections or for Profiler runs during hydrotesting.
The ACTIVE CUFF technology can also be used to increase the cross-country ability and smooth movement of the inline PIG in the Profiler head section.
Smooth movement at a given speed significantly improves the quality of the caliper data by eliminating the bounce of the measuring arms from various obstacles in the pipeline, and also reduces the wear of elastic elements (cuffs or support wheels) that carry the Profiler's weight.
In a pig with active cuffs, tested by APRODIT LLC, part of the liquid or gas is bypassed through an internal channel with a complex geometry. But unlike the "CONTROLLED BYPASS" technology, the gas flow is used not only to relieve pressure behind the pig, but also to mechanically drive the cuffs (or metal brushes). Swinging cuffs pull the inline pig along. This makes it possible to use pigs with active cuffs both in main gas pipelines and in gas outlets with relatively low pressure and gas flow rate.
Caliper PVM-06 with active cuffs
The method of moving the in-line PIG under the action of the rocking motion of elastic elements in contact with the pipe wall is patented (patent № 2392533).
Due to the pulling force from the active cuffs, the inspection or cleaning device smoothly and without stopping passes various bore in the pipeline. In addition, the gas jet flowing through the slug carries away the deposits raised by the inline slug downstream of the gas stream. This increases the permeability and efficiency of cleaning with an inline PIG, which is especially important for inspections and cleaning of old gas pipelines.