Tracking and locating are crucial activities during pipeline pigging to ensure the pig’s location and progress through the pipeline.  Pig Tracking and locating allow you to do the following:

• Confirm a stationary pig is or is not at the expected location e.g launcher or receiver.
• Locate a stationary pig at an unknown location.
• Confirm the passage of a moving pig at a particular location.

The terms “pig tracking” and “pig locating” tend to be used interchangeably – for the context of this post we will use “pig tracking” for both operations and we will be exclusively discussing Electromagnetic (EM) Technology.

The EM transmitter null spot allows for precise locating, enhancing your confidence regarding pig location and eliminating time and costs associated with locating a stalled pig.  EM systems are extremely versatile and can be used onshore, topside, or subsea with pipelines carrying liquid or gas and in trenched and pipe-in-pipe lines.  They are suitable for almost every application.  However, depending on the pipeline specification and the environment, challenges can arise.

1. Pipeline Depth and Wall Thickness

Pipeline depth and wall thickness are both factors that can affect the received signal strength of an EM transmitter.

Pipelines are often buried for several reasons such as to reduce the risk of third-party damage. However, the deeper the pipeline is buried, the harder it becomes to receive a signal from any tracking device fitted to the pig.

Heavy wall* pipes are often used to overcome technical challenges such as high pressure and temperature or use in deepwater applications.  A heavier wall provides a greater barrier for EM signals to pass through, resulting in signal attenuation.

There are adjustments you can make to the equipment.  For example, you can increase the gain on the EM receiver but this could lead to a poor signal-to-noise ratio – it is important to balance the sensitivity with accuracy of detection.  Alternatively, you can increase the signal strength of the transmitter which sounds like an easy solution, but this will reduce battery life. Therefore, it is important to be aware of the length of your operation and how long you require a signal to be transmitted.       

At present, the most reliable way to tell if a reliable signal will be received is to carry out representative testing under simulated project conditions.

*For the purpose of this article we discuss carbon steel only.  Stainless steel signal attenuation is substantially less.

2. Pig Design

When it comes to pig design, it is crucial to find the right balance: selecting the most suitable design for the task is one aspect.  On the other hand, choosing the correct EM transmitter and mounting it to the pig in a way that optimizes signal can pose challenges.

IK Trax recommend that as large a transmitter as possible is selected.

This is because a larger transmitter is fitted with more batteries – this can be used to increase signal lifespan or signal strength – maximizing flexibility in the respect that it makes pig tracking easier.

• We can also provide guidance on mounting best practices such as the following:
• Reducing the amount of magnetic material surrounding the transmitter. 316 Stainless steel pig bodies provide a good balance of properties and cost.
• Adding slits to the body will help increase signal.
• Leave as much of the transmitter exposed as possible, where practicable
• The transmitter must be clamped to ensure no movement or vibration occurs as this could lead to damage.

We can work directly with customers and pig manufacturers to advise and ensure that the pig design does not compromise the performance of the transmitter and vice versa.

3. Small Diameter Pipelines

There are occasions when despite collaboration and communication between the customer, pig manufacturer and pig tracking supplier, fitting a transmitter to a standard pig is just not possible.  This is quite often the case when dealing with smaller pipelines of around 4” to 6” and the transmitter is too large to fit inside the pig body.  The temptation here could be to proceed without a transmitter and rely only on pig signallers or have no method of detection and hope that everything goes to plan…

The third option (and the one that ensures you sleep better at night) is to adapt the transmitter by fitting pig discs, effectively transforming the transmitter into the pig body.  As well as overcoming the issue of lack of space, this design has the added bonus of increasing the signal as it no longer needs to propagate through the pig body in addition to the pipe wall.

4. Stuck pig – now what?

Finally, the biggest challenge of all – what happens if my pig gets stuck?  A pig tracking system is often considered an insurance policy – it is there for peace of mind – but as we often experience in the “real world”, sometimes you just have to use it!

The implications of a stuck pig can be significant.  It can halt operations and cause potential delays in product delivery.  Retrieving a lost or stuck pig can be expensive and there are the additional costs associated with downtime and disruptions.

By following the recommendations provide earlier in this article, you increase your chance of a signal being detected but how do you increase the speed of detection to minimize these costs?

Firstly, you want to be able to narrow down the search area.  This can be done by placing non-intrusive pig signallers at set distances and/or at pipeline features such as valve stations.  They are fitted downstream of the valve so the operator knows that valve can be closed if needed.

Click here to find out more about non-intrusive pig signallers.

You can also reduce the length of search area by tracking the pig as it moves using a method called “leapfrogging” whereby an operator travels ahead of the rest of the team to the next location, ready to detect the pig as it passes.

Secondly, you will want to know the range of your transmitter, also known as the detection envelope.  The detection envelope is the standoff distance from the pipeline combined with the distance upstream and downstream of the transmitter.

To find a stalled pig, you would typically move along a pipeline, pausing at regular intervals to attempt signal detection.  Without knowing the detection envelope of your transmitter, you run the risk of missing the signal (larger steps) or taking longer than is necessary (smaller steps).  The optimum step size is roughly half the width of the detectable envelope which should help you not only locate the pig but also do so in a relatively short timeframe.

Conclusion

Electromagnetic (EM) pig tracking is vital for pipeline operations. While EM technology is versatile and accurate, it faces challenges like pipeline depth, wall thickness, and pig design. The potential of a pig getting stuck emphasizes the need for effective tracking to prevent costly delays. By addressing these challenges through equipment adjustments and effective strategies, setbacks can be minimized and pipelines can operate more efficiently.

Get in touch to discuss your pig tracking challenges with our team.  

Electromagnetic Pig Tracking systems have an array of advantages that can improve operational outcomes.  In this article, we will explore six key benefits of using EM pig tracking systems and how they can transform your pipeline pigging operations. 

1. Accurate Locating

One of the advantages of an electromagnetic pig tracking system is its accuracy. An inherent null spot is detectable using an EM Receiver meaning that the operator can confirm the location of the transmitter to within a few centimetres.  This accuracy ensures that operators don’t have to second-guess the pig’s location. 

2. Operational Efficiency

By knowing the exact location of a pig, whether at launch and receipt or in the rare occurrence it stalls, operators can progress other operational activities with assurance.  This results in time and cost savings for the entire operation.

3. Reduced Operational Downtime

If a pig was to stall , being able to quickly locate and rectify the problem minimizes downtime.  This is extremely beneficial as the operational and financial implications of prolonged downtime can be significant.

4. Enhanced Confidence

EM Pig Tracking systems are not just for locating stalled pigs.  They can also provide you with the confidence and assurance that your pig is located precisely where you believe it is (and need it to be!)  An example of this is confirming that a pig has been fully received and has safely passed the valve, allowing it to be closed. 

5. Cost Savings

The initial cost of an advanced pig tracking system might seem high compared to older methods and models.  However, its enhanced reliability and accuracy, combined with complementary Apps that facilitate the locating process, lead to long-term savings by reducing downtime and operational issues.  This makes it a more cost-effective solution in the long run.

6. Adaptability

EM pig tracking systems are very versatile and provide reliable tracking and locating in a variety of different conditions.  This includes onshore, topside or subsea, pipelines carrying liquid or gas and in trenched and pipe-in-pipe lines.  This means that equipment can be used for multiple projects. 

Electromagnetic pig tracking systems are crucial for modern pipeline operations.  With their pinpoint accuracy and adaptability, they provide long-term cost savings and increased operational confidence.

Once good enough, no longer.

Intrusive Pig Signallers

Intrusive Pig Signallers have been around a long time and really haven’t moved forward to meet the needs of modern Pipeline Control or Pipeline Control Rooms.  Typically, in the past the pig sig was tripped and a Field tech on site communicated the pig passed message and reset it for the next run…. Or did they?  Sometimes, the Intrusive Pig Signaller didn’t trip due to poorly maintained internals or because of improper installation in the pipe.  Later, to help cut some of the costs, the addition of relays in a junction box were added to provide some indication when the Intrusive Pig Signaller did trip to a SCADA RTU.

Meeting the needs of today and tomorrow

Non-Intrusive Pig signallers today provide local indication with Flashing RED lights upon pig passage, remote indication to control room via Relay outputs and Analog 4-20mA signals (if you don’t have relay input slots available on your RTU) . MODBUS RS485 is available so that data from any specific unit can be viewed in the control room live and after the event. The MODBUS connection allows data logging, information viewing & reprogramming.

If there is no tie in to the control room via SCADA or other operators require the information direclty, Long Range Radio connection (LoRaWan) high security (chirp spread spectrum) with daisy chain systems that can communicate for many miles/kilometres is.  Equally Satellite Communication & GSM are available.

Non-Intrusive Pig Signallers are smarter, longer lived, more capable of describing the passage and as mentioned briefly in the 3rd instalment there are also many more options than just simple hall effect magnetic indication.  3 axis Magnetometers provide description and direction of detected magnetic signals.  Settings can be customized to detect the approach of ILI tools as differentiated to simple maintenance pigs. 

Ultrasonic Active pig trackers can be programmed to ignore sand and bubbles and just look for the appropriate amount of missing return pulses.  Acoustic trackers can listen to the characteristic approach and pass characteristics a pig in a line.

Non-Intrusive trackers provide more detection options, more detection signal characteristics, more communication options, and easier installation than older generations of equipment.  Non-Intrusive Pig Signallers are ready made to work with your digital twin representations in the SCADA control system and diagnostics to provide much more information to your Machine learning and AI predictive software.

Let us know your needs so we can arrange field trial units and training for your personnel.

Intrusive pig signallers, by definition, require pipe penetrations which provide potential Gas, Oil or other Hazardous material leak paths to the air, water or ground.  Any of these leak paths could result in investigation costs, clean up costs and decreased public confidence in the safety of the facility.

Non-Intrusive Pig Signallers by definition, do not.

Intrusive Pig Signaller maintenance, for any reason, involves exposing the Field Technician to potential pressure related and hazardous material related opportunities for injury. Proper instructions, training and experience can minimize this possibility but not eliminate it as seals or valves can malfunction and lose their capacity to protect against hydrocarbon pressure.  Not only could the Field Technician and other employees be exposed, but so could the surrounding community.

Non-Intrusive Signallers do not require pipe penetrations.  Enclosures for the sensors and relevant electronics are rated and clearly marked for safety in the environment in which they will be exposed by third party organizations independent of the manufacturer.   Battery powered units can be lifted off the pipe easily and removed from the hazardous area for change out of batteries.   Local power units can operate years without requiring entry into the enclosure.   Non-Intrusive indicators offer local and remote indicators of pig passage without having to send a Field Technician into the area. 

No pressure retention, therefore no leak paths, Minimal Field Technician exposure to the environment, and 3rd Party safety certification for the equipment.

It’s that simple.

Changing your Intrusive Pig Signallers to Non-Intrusive Pig Signallers improves the safety of your employees, processes, and the surrounding community.

Electromagnetic Pig Tracking is often considered to be a complex process, requiring savvy operators with years of experience.  However, enhanced technology and the digital age have brought Applications for both Transmitters and Receivers into the market that can facilitate the whole process.  Here are five reasons why you should add Applications to your pig tracking toolkit.

1. Reduces downtime and costs

Pig Tracking Receiver apps provide a graphical representation of the signal from the Receiver and, when used in conjunction with a multi-frequency model, provide a clear view of the different frequencies being received, allowing you to identify individual, multiple pigs.  Additionally, they remove potential ambiguity over received EM signal further simplifying the process.

All of this can lead to faster detection and reduced vessel and/or downtime and subsequently, reduced costs.

2. Additional flexibility for the user

Historically, pig tracking users did not have the capability to change the settings on the equipment.  Dependent on transmitter model, they may have had the option to toggle between two different (pre-determined) pulse rates but to change other parameters such as pulse length, frequency and power output, the unit had to be returned to the manufacturer.  Without careful forward planning, this could result in delays and came with additional cost and inconvenience.

With software such as Online’s EMTx Config App, the operator now has the flexibility to easily make these changes on site without returning to the manufacturer.  Additionally, Online EMRx receivers can be modified on site by changing the frequencies that are displayed on the LEDs using the Receiver Apps.

3. Ability to review data

Receiver Apps typically let the user pause, zoom, and scroll through past data, allowing them to customize their experience and gain further insight into the detected signals without any time pressure.  It also means that, assuming the operator has placed the receiver on the pipeline, they do not have to be present to witness the signal being detected locally on the receiver itself.

4. Provides an exportable record of pig tracking operations

In addition to being able to review past tracking data, markers can typically be used in Receiver apps to highlight areas of interest.  These markers along with the tracking log can be exported to provide a record of signal received during the pig run.  This can be particularly useful as a means of providing supporting data to the client.

5. Make decisions on suitable pulse rate for the project

Before the introduction of Pig Tracking Apps, operators had to work closely with the manufacturer to determine the most suitable pulse rate for their transmitter based on their required battery life.  However, it is now possible for the client to use the EMTx Config app to first determine the most suitable pulse rate and then make the adjustment.  This saves time and is far more convenient for the client.  It also ensures they are setting the transmitters at the appropriate rate for their specific project and not working with previous settings, which may not be optimal.      

Contact us to find out more about our range of Android and Windows Applications.