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APRODIT Transmitters, locators, cleaning pigs, scraper-calipers, form-measuring pigs

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Aprodit Ltd.
Russia, Moscow Region,
Kolomna, Oksky prospect, 40
+7 (999) 845-19-75 (English)

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Caliper PIGs of SKT line
Caliper PIG SKT-250

Caliper PIGs are designed for detection of narrowings in a pipeline before cleaning or diagnostic PIGs are launched in the pipeline.

Due to their ability to pass narrowings 65% of outer pipe diameter the SKT PIGs can pass the most difficult sections of the pipeline without any stop.

Deformations of installed on the PIG metallic measuring discs will give the information about presence of narrowings in the pipeline which can stop a form-measuring or cleaning PIG. Such places of the pipeline (if found by SKT pig) should be repaired.

SKT caliper PIG can be supplied with low-frequency transmitter and without it. Presence of the transmitter enables to trace how the PIG moves inside a pipeline. And in case the PIG stops somewhere in the pipeline then there are 40 days to find it with use of low-frequency locator while the transmitter emits signals.

By the amount of debris carried by SKT caliper PIG into receiving chamber it is possible to evaluate the scale of pigging which will be necessary to clean the pipeline.


Dimensions of SKT PIG body and geometrical parameters of polyurethane discs were selected in the way to allow passage of the PIG through the following peculiarities of a pipeline:

  • Narrowings up to 65% of outer diameter of the pipeline;
  • Pipe bends 90 degrees with radius 1.5 Dn (according to GOST 17375-2001);
  • Equal diameter T-joints without grid with lower position of the joining pipe;
  • Smaller diameter pipes protruding inside the pipeline (vantuz);
  • V-valves and gate valves.


Parts composing the body of the PIG are manufactured as thick-walled parts and made of strong plastic. Carrying and simultaneously cleaning discs are made of wear resistant polyurethane with Shore hardness 75...85.

In-line caliper PIGs of SKT series were certified in accordance with TR CU 010/2011 "On the safety of machinery and equipment".

Certificate of Conformity of the Customs Union - a document certifying the conformity of products with technical regulations and providing of certified products in Russia, Belarus and Kazakhstan without additional requirements and without additional assessment procedures.

Certificate TR CU 010/2011 "On the safety of machinery and equipment"


In case of caliper PIG ordering please write SKT-XXX-T, where

XXX should be nominal diameter of the pipeline in millimeters,

Specify T when the PIG is ordered with transmitter. In case the PIG is ordered without transmitter then T in the name is not written.

For example: Caliper PIG of SKT line for launching in a pipeline which linear part is made of pipes with outer diameter 325 mm (diameter orifice D=300 mm), equipped with low-frequency transmitter PNT-00 (without telemetric module) will be described as caliper PIG SKT-300-T.

Diameters of measuring (caliper) discs are determined based on outer diameter of the pipeline. Usually two measuring discs are installed 85% and 70% of outer diameter.

For works in pipelines with thick walls (15mm and more) it is necessary to provide us information about the pipes wall thickness.


Caliper PIG SKT-700 with body made of steel

SKT-500 for cleaning of pipeline

Low-frequency transmitter is installed completely inside the body of SKT PIG which body is made of plastic or hard polyurethane. These materials do not reduce the strength of electromagnetic signal from the transmitter (magnetic field pulsing on frequency 22Hz). Due to this fact it is possible to install the transmitter completely inside the body of the PIG with no risk to diminish the distance from which the PIG can be "seen" by low-frequency locator. And it enables to reduce overall dimensions and weight of the PIG.

The body of the caliper PIGs for pipelines with diameter 530mm and more is reasonable (from economic point of view) to make from steel. In this case it is necessary to attach the transmitter so that half of it length is out of the steel body of the PIG. It is made to prevent considerable reduction of the transmitter signal strength (see an explanation here). And in this case it is necessary to protect the transmitter by a bumper (i.e. metallic cage).

In case PNT-01 transmitter with telemetric module is installed in SKT PIG then all contacts of metallic measuring discs with pipe wall are recorded into internal memory of the transmitter with reference to the time when these hits happened. This information enables to find position of the narrowings in the pipeline. So total time for finding and elimination of of all severe narrowings in the pipeline is reduced.

In some cases special utility PIGs are necessary for cleaning of "difficult" pipelines which have narrowings more than 15% of diameter. For example if remaining cross-section has small dimention of only 65% from the pipe diameter. For such cases we offer SKT without metallic kalibr discs. SKT clean the internal surface of the pipeline not so good as USO cleaning PIG do. However ability to pass through narrowings and hence the risk of stops inside "difficult" pipeline for SKT is smaller than for USO.

Polyurethane cuffs can be installed on SKT instead of cleaning discs.

Based on SKT family design we developed a set of PIGs for cleaning of so called telescopic pipelines. I.e. the pipelines which were welded from pipes of different diameters. For example from pipes diam 325mm and diam 377mm. We called such PIGs as telescopic SKT PIGs.

They have sloted polyurethane discs along with conventional discs. Due to this design the PIG can clean well the pipeline where other PIGs are not sutable. Telescopic SKT PIGs go through bends with radius R=1.5D and narrowings with cross-section dimension 70% of outer diameter D (in the pipe bigger by diameter).

For example for cleaning of a pipeline made of pipes with outer diameter 219mm and 273mm we offer cleaning PIG called SKT-200-250. Pipes wall thicknesses don't matter in this case.

Low-frequency transmitter PNT can also be installed inside any telescopic SKT PIG. So there will be possibility to trace the PIG motion inside the pipeline.

Telescopic SKT-200-250 PIG


Instead of low-frequency transmitter PNT in a PIG one can install a low-frequency transceiver PPNT, which has the same attachment dimensions. The main difference of the transceiver is that it can be switched to the lowest level of power consumption (sleep mode) right through the metal walls of the closed launching chamber of pipeline walls. In this case, a PIG with the transceiver can be located inside the launching chamber under pressure for several days or even weeks. Thereafter, it can be switched on to function as a conventional transmitter 22 Hz without opening the chamber.

To send a command through thick closed metal (or reinforced concrete) wall special transmitter is used, which also operates at 22 Hz. As the transmitter (remote control) a modified transmitter PNT-04 is used now. In future the function of 22 Hz remote control is planned to be added to modified LF locator NPR-00.

Thanks to the disassemble housing from polyurethane (or polyamide) bushings, various modifications and configuration of SKT PIs are possible. The modifications include changes in the number and location of polyurethane cleaning and supporting discs or cuffs, installation of various additional equipment, magnets and brushes.


Three-way Ball Valve for a pipeline 12".short PIG for three-way Ball Valve  DN 300 mm

All-urethane SKT-3D1M-114 with transmitter PNT-08All-polyurethane SKT-3S1M-114 in the ball of pigging valve

We can deliver short version of SKT PIG with the body made of rigid polyurethane bushes or all-polyurethane solid-casted PIGs for automatic launching via three-way Ball Valve.

In all these short PIGs one can insert low frequency transmitter to track and search the PIG while it is moving through a pipeline.

The illustration shows short PIG for three-way Ball Valve in the pipeline with diameter DN = 12" (300 mm) and for diameter DN=4" (100 mm)


Manufacturer: APRODIT Ltd.
140402, Russia, Moscow region, Kolomna, Okskiy prospect 40.
Have a question? Please contact us by phone +7 (916) 674-82-59 (English) or by e-mail