A Rundown Of Utility Pipe Pigging And Its Many Variations
Utility pipe pigging, often simply referred to as pipeline pigging, is a vital technique used across numerous industries to maintain the functionality, safety, and efficiency of pipe systems. At its core, this process involves the insertion of devices known as “pigs” into the pipeline. These pigs, available in various shapes and sizes, are propelled through the pipe by the flow of product or an external force, performing essential tasks like cleaning, dewatering, and sealing. Carrying out pipeline pigging ensures that pipelines remain free from blockages, corrosion, and debris buildup, ultimately enhancing operational efficiency and prolonging the lifespan of the infrastructure.
As the pig travels down the entire piping system and scrubs down its interior surface, it eliminates debris and contaminants that may hinder optimal flow. Often equipped with features such as brushes or sensors, utility pigs are designed to cater to diverse operational needs, offering both cleaning and diagnostic capabilities. Additionally, dry disconnect couplings play a crucial role in ensuring safe and efficient product transfers, preventing spills and contamination during pigging operations.
Given the many subcategories of utility pigging available, how can you determine which methods and tools are most suitable for your specific requirements? Below, we explore the most commonly used types of utility pigging and their unique benefits to help you make an informed decision.
1. Foam pigging
Foam pigging mainly makes use of polyurethane foam pigs, which are highly effective for removing debris and liquids from pipeline systems. As the simplest type of pig, foam pigs come in varying densities to match the specific level of contamination within the pipes. Their standout features include a lightweight, flexible, yet durable structure that enables them to adapt to changes in pipe diameter, sharp bends, and other challenging geometries.
Versatility is one of the hallmarks of foam pigs, with configurations and designs available to suit a wide range of project requirements. Foam pigging excels in applications such as batching and light cleaning. While spherical pigging – a related technique discussed next – can also handle these tasks, foam pigging offers superior cleaning power.
However, foam pigging has its limitations. Its polyurethane composition delivers a gentler cleaning action compared to pigs made from denser materials like steel, making it unsuitable for more aggressive cleaning needs. For operations requiring enhanced scrubbing force, an alternative pig type would be more appropriate.
2. Spherical pigging
Spherical pigging leverages pigs that are made in the form of solid or inflatable spheres, typically made from materials such as polyurethane or neoprene. Inflatable spheres are often filled with water or glycol, allowing them to maintain their shape despite pressure fluctuations within the pipeline. Thanks to their spherical design, these pigs can move swiftly through piping systems, ensuring efficient performance.
Despite their advantages, spherical pigs require additional design considerations, often leading to higher costs. They also tend to become undersized during use, which can compromise their cleaning effectiveness compared to other pig types.
Spherical pigging is best suited for tasks like batching and liquid removal. While foam pigging is also an option for these applications, foam pigs typically offer a cleaning advantage, making them a more effective choice for tasks that demand a higher degree of debris removal.
3. Batch pigging
Batch pigging creates a reliable barrier between different products flowing through the same pipeline, effectively separating substances to prevent cross-contamination. This process also optimises product flow and can be used for displacement or filling lines with water.
The primary advantage of batch pigging is its efficiency. By enabling simultaneous cleaning and displacement, it maximises resource use. Transporting multiple products through one system is also more economical than installing separate pipelines for each. Batch pigs offer versatility, available in unidirectional designs with scraper cups or bidirectional ones with discs.
However, batch pigging’s effectiveness depends on maintaining the same velocity as the product stream. If the pig starts and stops inconsistently, its performance may diminish.
4. Sealing pigging
Sealing pigging primarily prevents leaks using polyurethane or rubber pigs, which combine durability with flexibility to adjust to varying diameters and bends. Solid cast pigs, with their compact design, can also be used as a substitute for sealing pigs when needed.
This method is especially effective for flushing liquids out of a pipeline and preventing air or moisture from entering. By maintaining an airtight seal, sealing pigging ensures optimal system integrity and reliability.
5. Solid cast pigging
Solid cast pigging employs steel or polyurethane pigs with no moving parts to clean and inspect pipelines. These compact pigs excel at removing debris and can handle tasks like cleaning, batching, gauging, displacement, and even as a substitute for sealing pigging.
While their durability is an asset, steel pigs’ density can pose challenges if they become lodged in a pipeline. Polyurethane pigs share a similar risk. Despite this, solid cast pigs remain a robust choice for demanding applications, offering efficient cleaning and adaptability for multiple purposes. Attachments like discs or brushes can be added for specific tasks, enhancing their versatility.
6. Ice pigging
Ice pigging stands out as the most unique method on this list, utilising slurry ice instead of a solid pig to clean pipe interiors. This approach eliminates the risk of blockages, as the slurry melts over time, and it doesn’t require a launcher or catcher, significantly saving time and effort.
The malleability of slurry ice allows it to adapt easily to varying pipe sizes and bends, offering flexibility unmatched by traditional pigs. However, ice pigging is less effective at removing severe corrosion or calcified fats, greases, and oils. Additionally, its inability to be tracked and its tendency to melt if stuck reduce its capacity for detecting obstructions. This means ice pigging is best suited for small-bore piping. For larger pipelines, it is only recommended when navigating numerous twists and turns that solid pigs cannot manage.
Conclusion
Utility pipe pigging comes in a diverse range of methodologies that are each tailored to specific operational needs. From the adaptability of foam and ice pigging to the robustness of solid cast and sealing pigging, every approach has its strengths and ideal applications. Hopefully, the contents above provide you with a better understanding of these pigging techniques so you can make informed decisions as to which solution is right for your needs.
Pharmchem Engineering is here to help you achieve operational excellence with our high-quality, fully-tested industrial supplies. Whether you need tailored solutions for high-risk workplaces or advanced components like expansion joints and pipe pigging equipment, we’re committed to delivering performance and safety. Reach out today and discover how we can support your business with industry-leading solutions.
