Solutions Engine

Pig Passage

By sensing the passage of pigs, spheres, and inline inspection (ILI) tools as they travel through the pipeline, pig passage indicators add confidence to Offshore Pipeline pigging operations.

Also known as a PIG-SIG®, a term that originated with TDW decades ago, pig passage indicators are installed at prescribed locations along the pipeline. As the pig passes the PIG-SIG indicator, the signal is tripped and an above ground flag or electronic display appears. Not only do pig passage indicators identify that a pig has successfully traversed from the launcher to the receiver, they can help point to a problem, as well: a pig failing to trip the signal can mean that the pig is stalled, stuck, or lost.

TDW can help pipeline operators choose the appropriate pig passage indicator for their specific needs, manage installation, and ensure smooth operation.



Ensuring that Offshore Pipeline operators have chosen the appropriate tool is vital to successful installation and operation. To select the right pig passage indicator, it’s important to understand these basic pipeline parameters:

  • Product type
  • Line pressure
  • Temperature
  • Wall thickness
  • Pipeline diameter 

TDW offers three pig passage indicators:

  • PIG-SIG® V pig passage indicator – Built to withstand the most brutal environments, onshore and offshore. Available with flag indicators that provide local indication, electrical indicators for remote indication, or a combination of both. Because the trigger that trips the signaling mechanism is omnidirectional (an upgrade over the PIG-SIG® IV), the PIG-SIG V is easy to install and significantly reduces the risk of trigger breakage.
  • PIG-SIG NI non-intrusive pig passage indicator – A simple and reliable non-intrusive tool to detect pig passages anywhere within a pipeline system. Easily banded onto the line, with no tapping required.
  • PIG-SIG IV pig passage indicator – Available with a flag indicator, electrical indicator, or a combination of both. Manufactured for durability and weather resistance. 

Technical assistance is available from TDW subject matter experts for special circumstances or if the path to a solution requires consultation.


In the Offshore Pipeline market, risk reduction is of utmost importance. If an operator needs to access a pipeline during a planned shutdown — for projects ranging from establishing purge points to adding a thermowell — TDW offers safe, proven hot tapping solutions.

The tapping process calls for a high-pressure fitting, valve, and tapping machine – all working together to provide a safe and effective solution for creating an access point into a pipeline. This access point can then be used for inserting small probes, such as TDW PIG-SIG® pig passage indicators, or a multitude of other small sensors.

Whether operators are purchasing equipment to perform their own hot tapping and isolation jobs or turning to TDW to execute the service for them, they can rely on the TDW line of equipment and consumables. For example, the T-101 machine is the industry standard for small tapping projects, and when operators purchase a T-101 machine directly from TDW, they have the option of receiving training as part of the TDW Training Department’s LineMaster™ program. TDW offers the highest quality of training, which aligns with U.S. Department of Transportation operator requirements.

TDW can also partner with operators before the work begins, providing consulting services to help them make optimum use of TDW products and services. TDW application engineers are recognized industry experts, ready to assist operators through each project phase – from start to finish.