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No moving forward without it

Published by , Editorial Assistant
World Pipelines,


Rolf Gunnar Lie, T.D. Williamson, Asia Pacific, introduces a bespoke recovery tool that rescues stalled pigs and enables isolation.

Rescuing a stalled cleaning pig isn’t usually on the prepipeline isolation to-do list. After all, most pigs travel through pipelines without a hitch, doing their job of improving throughput across thousands of miles of line each day. So, when a third-party vendor’s bi-directional (Bi-Di) cleaning pig stalled in the production tee of a 28 in. natural gas export pipeline offshore southeast Asia, it came as a surprise to the operator.

Although the pig wasn’t entirely obstructing product flow, the operator was worried that inline conditions could increase both pressure and bypass. If that happened, it could push the pig further into the pipeline and create a blockage that could shut down production for days if not weeks. With gas export pipelines like this one transporting millions of dollars in product every day, the operator was highly motivated to avoid that possibility.

A potential service interruption wasn’t the only urgent reason for extracting the stalled pig, however. The operator had discovered that two pig trap valves on the platform were internally leaking, meaning they didn’t seal completely. The company was understandably eager to get them replaced.

Replacing leaking valves is not uncommon, but it requires creating a safe work zone first. And that means the operator must make a choice that can affect production, downtime and the environment. Either they can blow down the entire pipeline to make it hydrocarbon-free, or use inline methods to isolate just the section where the work will take place.

Considering that depressurising the entire 300 km (186 miles) pipeline would result in something like 300 million ft3 of inventory loss through flaring and would add a week to the turnaround time, it hardly seemed like a viable option to the 33 operator. Knowing that T.D. Williamson (TDW) SmartPlug® technology had been proven in offshore operations made their decision to go with inline isolation even easier.

Of course, before TDW could even think about isolating the pipeline, the third-party stalled pig had to come out, or it would prevent them from pigging the SmartPlug tool to the set position. And before TDW could rescue the pig, they had to do two things: figure out why it stalled in the first place, and develop a bespoke recovery tool.

First things first

Recovering a stalled pig isn’t like getting a clog out of a drain – it can be a complex undertaking depending on where the pig has become stuck in the pipeline ...

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Read the article online at: https://www.worldpipelines.com/special-reports/23122022/no-moving-forward-without-it/

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This article has been tagged under the following:

Asia pipeline news Pipeline pigging news Pigging and inspection news