Form-measuring PIG is a device, which moves inside a pipeline and collects information about geometrical parameters of internal surface of the pipeline. It also checks if cleaning and diagnostic in-line PIGs can pass through this pipeline without damage.
Form-measuring PIGs manufactured by APRODIT pass pipeline narrowings 70% from nominal diameter D of the pipeline and pipeline bends to 90 degrees with minimum radius R = 1.5 D.
Using system of levers which are in contact with internal surface of the pipe the form-measuring PIG determines shape of pipeline cross-sections, presence of protruding welds, geometry of taps and valves and other peculiarities of the pipeline. Having system of several independent odometers the PIG determines distance from launching chamber to detected peculiarity.
The PIG works in liquid, gaseous and multi phase substances including explosive. Safety of the PIG in hazardous media is determined by use in its design only intrinsically safe electrical circuits and by inserting of all electronic components into explosion proof casings.
The form-measuring PIG is equipped by low-frequency transmitter. Signals from the transmitter are recorded in marker points of the pipeline by receiver-registrators. This benchmarking helps to increase the accuracy for determining of the distance to a peculiarity or a defect in the pipeline. Also transmitter is used for tracking of a PIG and for its search in case the PIG unexpectedly stops somewhere in the pipeline.
Special table for preparation of the PIG before launch in a pipeline and for transportation is included into delivery set. For adjusting of the PIG for particular range of diameters there is a set of spare parts also included into delivery set.
Form-measuring PIGs of PM line which are produced since 2006 are successfully used in pipelines with diameters 400 to 900 mm.
Form-measuring PIGs of PVM line is the second generation of form-measuring PIGs developed by APRODIT. For this new generation we updated design and electronics making them more compact. Also "ACTIVE CUFF" technology has been applied in the towing section of PVM PIG. With this technology the the speed of PIG motion inside a pipeline is more stable and it better passes narrowings and peculiarities in the pipeline.
Application of Active Cuffs make it possible to use the form-measuring PIG in just built pipeline. It can be moved through this pipeline by compressed air while another end of the pipeline is opened to the atmosphere (work "on opened end"). And in gas pipelines which are long in service it is possible to run PVM PIG without increasing gas pressure and gas transportation rate. So the PIG will move with the preset velocity, which is less than rate of gas flow. Also it won't stops and then accelerates on the peculiarities of the pipeline. And there won't be "jerks" in its motion.
Smooth motion at a given speed significantly improves quality of the geometry survey by eliminating rebounds of measuring levers from various obstacles in the pipeline, as well as reduces the wear of the elastic elements (cuffs or supporting wheels), bearing the weight of the form-measuring PIG.
PVM-06 (second generation)
Form-measuring PIGs of PVM line move smoothly even in low pressure gas pipelines which works "at the open end" due to the use of technology "ACTIVE CUFF"
The geometry measurement tool moves through the pipeline with the flow of fluid. While moving it collects information about the state of the internal profile of the pipe walls, as well as about parameters of motion.
Determination of geometry for cross-section of a pipeline is being made by set of levers which are always in contact with internal pipe wall and are evenly distributed in circumferential direction. Angular position of every lever is recorded into internal memory several times per second.
After the geometry survey the following results are obtained:
Detection of defects in internal surface like goffers, narrowings, dents;
Positioning of the defect by distance and by angle;
Detection of design peculiarities of the pipeline like circumferential welds, T-joints, bends, etc. as well as their position by distance and by angle;
Determination of horizontal and vertical profile of the pipeline axis.
The information gathered in the course of in-line survey is recorded into internal memory of the tool. After passing through the entire distance this information is transferred to an external storage device for further computer processing and interpretation. Then a report of prescribed form issued based on the results of the form-measuring PIG survey.
To improve accuracy of the measurements in the extended range of product pumping velocities a number of design solutions such as "CONTROLLED BY-PASS " and "ACTIVE CUFFS" are used in the design of advanced in-line PIGs.
In the PIG with the controlled bypass the gas is bypassed through the inner channel. Inside the channel there are flaps that change the flow area of the channel under the action of actuators, controlled by electronics. This technology has been widely used in diagnostic in-line PIGs for gas pipelines with high pressure and high velocity of gas transfer.
In the PIG with the active cuffs, designed by APRODIT, the gas is also bypassed through the inner channel. But unlike "CONTROLLED BYPASS" technology, the flow of gas is used not only for pressure relief over the PIG, but also for mechanical drive of cuffs or metal brushes. Rocking cuffs pull the PIG with additional force. This allows to use the PIGs with active cuffs not only in the main gas pipelines, but also in the gas pipelines with relatively low gas pressure and flow.
The way to move an in-line PIG under the influence of rocking motion of elastic elements in contact with the wall of pipe is patented (patent number 2392533).
Thanks to pulling effort from the active cuffs the diagnostic or cleaning Pig passes various narrowing in the pipeline smoothly and without stopping. In addition, a jet of gas flowing out through the PIG, takes away deposits, raised by the PIG, down to the gas flow. This increases the passability and efficiency of cleaning pigs, which is especially important for the diagnostic and cleaning of old pipelines.
APRODIT also offers services for the survey by form-measuring PIG and for cleaning work in gas pipelines recently built up and now delivered to exploitation by the PIGs equipped with active cuffs. This technology allows effectively carry out these works in pipelines, once considered unsuitable for the passage of PIGs moving under the action of compressed air or natural gas under relatively low pressure.
Manufacturer: APRODIT Ltd.
140402, Russia, Moscow region, Kolomna, Okskiy prospect 40.
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