A variety of conditions can make it difficult for Gas Transmission operators to pig their pipelines for cleaning, maintenance, or inline inspection (ILI), leading them to believe that their system is unpiggable. In reality, any system can be modified and made piggable. And with expanding regulatory requirements for inline inspection – and the fact that pigging can contribute to pipeline productivity and profitability – improving piggability is essential.
Pigging is often impeded by pipeline design characteristics – including tight, mitered, or forged bends, certain types of welds and connections, and dual- and multi-diameter pipe sections. Some valves, particularly older gate valves, obstruct pig passage; in fact, valves are the leading cause of stuck pigs and other pigging problems.
In the case of pipeline acquisitions, absent or incomplete records can lead to piggability concerns. And of course, systems without pig launchers and receivers cannot be pigged at all.
Conditions inside the pipeline – such as internal damage and the build-up of debris, sediment, and other flow-restricting materials – also cause pigging challenges. Because pigs are pushed along by product pressure inside the pipeline, low flow rates may cause stopping and starting, preventing the pig from performing effectively. Conversely, pigs running in high velocity product streams can also be less effective.
TDW helps operators improve piggability for:
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The installation of pig launchers and receivers is one key to making a system piggable. TDW offers Gas Transmission operators both conventional launchers and receivers and automated pigging systems that enable pigging access without interrupting flow.
In addition, TDW provides cleaning pigs that remove liquids and debris to maximize throughput and mitigate corrosion growth.
Launchers and receivers:
Technical assistance is available from TDW subject matter experts for special circumstances or if the path to a solution requires consultation.
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In the Gas Transmission market, where pipeline shutdown may not be an option, hot tapping and plugging (HT&P) technology allows operators to complete pipeline replacements and modifications – from making lines piggable to line lowering and relocations – with minimal flow interruption. TDW HT&P solutions protect customers’ revenue stream while minimizing risk – and are available for a wide spectrum of pipelines, environments, and products.
The HT&P process incorporates a high pressure fitting, valve, tapping machine, and isolation technology – all working together to provide a safe and proven isolation solution. Once the area of pipeline that needs work has been safely isolated and evacuated, the line modification can be performed.
The full suite of isolation solutions offered by TDW plays a critical role in this process. The TDW STOPPLE® Train isolation system, for example, uses double block and bleed technology to help increase efficiency and safety during pipeline modification. The system – which only requires a single pipeline tap – reduces costs associated with fittings, valves, welding, and inspection services. The bleed port affixed on the line ensures that any product that bypasses the first seal is contained and evacuated through the bleed port, which creates a safe zone in high-consequence areas.
Whether operators are purchasing equipment to perform their own HT&P jobs or turning to TDW to execute the service for them, they can rely on the broad line of TDW equipment and consumables. The company engineers and manufactures nearly every component needed for an HT&P project, and TDW tapping and isolation equipment is considered the industry standard.
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.