Pathfinder® Foam Caliper Tool

The Pathfinder® Foam Caliper Tool is a pipeline inspection device with a high level of mechanical compliance, which is capable of negotiating severe restrictions in a pipeline with minimal risk of blockage or damage.

Pathfinder has been developed for the first stage assessment of operational pipelines prior to the use of metal-bodied pigs. It can be used in conjunction with standard foam cleaning pigs to prove the bore of pipelines with unknown internal conditions, including :

  • New and operational pipelines which have not previously been pigged  
  • Operational pipelines which have suffered damage due to external interference but are inaccessible for external inspection
  • Operational pipelines with unknown levels and distributions of wax or scale deposits.

Key Features

The Pathfinder comprises a medium density polyurethane foam pig with a removable cartridge containing sensors, electronics and batteries located in the centre of the pig. Sensors measure the compression of the foam at points around the circumference of the tool, allowing the tool to identify and measure bore changes, dents, ovality, scale and wax deposits and other restrictions in the line. Other sensors measure the roll (clock position), tilt and heading orientation of the pig.

An onboard logging system (with real-time clock) collects and stores data from the sensors, allowing pipeline features and anomalies recorded in the data to be referenced to pressure and flow records. For pig sizes 8” and greater an electromagnetic transmitter can be included for tracking and operation of Pig Signalers.



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The Foam Carrier Pig is fitted with a caliper cartridge which is powered up by screwing in a ‘Run Plug’ before being inserted into the pipe. Caliper’s output can be downloaded and rechargeable batteries can be removed from the pig for download and battery recharge. The body of the pig can be re-used if undamaged or disposed of.

Data Analysis

An initial assessment of the data can be carried out on site. The output from the analysis is in the form of multi-channel plots which display radius, diameter and bore values. Accelerometer and gyro data can be used for the identification of girth welds and for the measure of bend angle and direction.


Pig SizesTo Suite Nominal Pipe Bore 4” to 28”
Foam Pig BodyMedium Density Polyurethane
Operating Pressure200 bar standard. 400 bar max.
Caliper Sensors8 to 24 Independent Caliper sensors
Orientation SensorsRoll, Tilt and Heading
Data DownloadUSB Interface to PC or Laptop
Bore PassingFull circumferential bore restrictions in excess of 30% (20% for the 4” tool)
Bend PassingMinimum bend radius of less than 1D
Operating Pressure200 bar (standard) 400 bar (max.)
Operating Temperature0°C to 70°C
Clock PositionOrientation sensors to identify which of the caliper sensors is at TDC on each scan
Tilt AngleAccelerometers measure the tilt angle of the pig relative to gravity
Bend AngleGyro sensors measure the heading angle of the pig allowing bend angle to be determined
Data Acquistion & StorageEach data scan collects and stores data from the caliper sensors, the accelerometer sensors and the gyro sensors.
Survey SpeedData quality is not significantly affected by pig speed, however, for identification and interpretation of features such as dents etc, a constant running speed between 0m/s and 2 m/s is recommended
Run TimeBatteries are rechargeable. The tool has sufficient battery capacity to provide a run time of 60 hours for the single battery pack version and 120 hours for the dual pack version.
Data DownloadData download is via a USB interface direct to a laptop or PC hard disk drive.