Utilising urethane cups and discs

The successful execution of an extensive 569 km pigging operation in a 20 in. natural gas pipeline from Nigeria to Ghana highlights the critical role of specialised urethane components. This article examines the contribution of long-range urethane cups and discs to the efficiency of the cleaning and inspection process. Manufactured by Pigs Unlimited and conducted by Topline Limited and Pipeway Engenharia, the operation employed various pigging tools, including foam pigs, multi-disc brush pigs, caliper pigs, and magnetic flux leakage (MFL) pigs. The focus is on how the properties of advanced urethane materials enhanced tool longevity, adaptability, and performance in a highly abrasive gas pipeline environment.

Introduction

Pigging operations in long-distance natural gas pipelines present significant challenges, particularly in terms of material wear, tool performance, and maintaining continuous flow efficiency. The abrasive nature of gas pipelines necessitates durable materials capable of withstanding prolonged exposure to high-velocity particulate contaminants. This study explores the role of high-performance urethane cups and discs in mitigating these challenges, ensuring successful tool passage, and optimising cleaning and inspection outcomes.

Project scope and operational challenges

The pipeline under discussion extends over a substantial distance of 569 km, presenting a complex operational environment. It functions under consistently high-pressure conditions and transports natural gas with variable compositions. These operational factors necessitated a comprehensive and carefully tailored pigging strategy to ensure efficiency, reliability, and tool longevity throughout the cleaning and inspection processes.

Achieving a successful pigging run over such a long pipeline required meticulous consideration of several key technical and operational challenges, including the following.

Extended pipeline length, and frictional wear

The sheer length of the pipeline significantly increases the distance over which pigs must maintain structural integrity and functionality. As pigs travel hundreds of kilometres, their components, particularly those in contact with the pipe wall, are subject to continuous friction. This leads to gradual material degradation, especially on the sealing and cleaning elements. Selecting materials capable of withstanding this prolonged wear was essential to ensure consistent performance from launch to receiver.

Abrasive deposits, and contaminant build-up

Over time, internal pipeline surfaces accumulate layers of particulate matter, such as dust, scale, and other solid residues. These contaminants not only restrict flow efficiency but also create an abrasive environment that can accelerate wear on pigging tools. The presence of sharp or granular debris increases the risk of damage to both the pig and the pipe. Addressing this challenge required tools that could effectively dislodge and remove debris while resisting abrasion.

Sealing efficiency, and propulsion requirements

Ensuring a reliable seal between the pig and the internal pipe wall is critical for propulsion, especially over long distances. Effective sealing ensures that the pig is pushed forward efficiently by the differential pressure of the gas behind it. Poor sealing can result in bypass, where gas leaks past the pig, reducing forward momentum and potentially leading to a stalled run. Achieving optimal sealing performance was a key design consideration, particularly given the pipeline’s internal variability due to scaling and diameter changes.

Tool fatigue from continuous exposure, and harsh conditions

Pigs used in long-distance operations are continuously subjected to high pressures, fluctuating flow dynamics, and mechanical stresses. Over time, this exposure can lead to tool fatigue, manifested in component failure or reduced operational effectiveness. The dynamic environment within the pipeline, compounded by the abrasive nature of the internal contaminants, can degrade conventional materials quickly. Tool resilience, therefore, had to be significantly enhanced to maintain structural and functional integrity throughout the run.

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Read the article online at: https://www.worldpipelines.com/special-reports/12062025/utilising-urethane-cups-and-discs/