hps bi-directional magnetised pig

Different Types of Pipeline Pigs

Many liquid processing industries, for example, food, beverages, confectionery, household goods, personal care, cosmetics, pet food, paint, and many others use pigging systems to recover product and clean the insides of pipes and tubing.

The most important part of a pigging (also known as ‘liquid product recovery’) system is the pipeline pig. While they may look simple, the pig is a highly specialist projectile that travels along the pipes. Because of the interference fit with the inside of the pipeline, the pig pushes out the residual product to its destination (tank, packaging, storage, whatever).

The result is improved yields, faster processing, and increased efficiency as well as significant savings on water, energy and cleaning fluids.

Pipeline pigs come in all shapes, sizes, materials, and designs. For example, some pigs have fins, discs, some are cylindrical, bullet-shaped, spherical, bone-shaped, some pigs are made from food approved materials and solvent resistant materials. In addition, pigs vary in performance, durability, reliability as well as quality.

The Problem with Single Directional Pigs

If you have used HPS pigs before, then you’ll know the pig is a unique, cylindrical-style shape with full-contact design. You’ll also know that one of the many features of the pipeline pig is that it’s bi-directional. In other words, it can travel either way along the pipeline. This is extremely important in process pigging systems.hps pipeline pig

However, this is not the case for all pigs in the process pigging industry, as some are designed where they can only travel in one direction.

The problem with these types of pigs (single directional pigs) is that they severely limit pigging system design and process efficiency, particularly regarding automation. In some cases, the pig needs to be removed manually and returned to its launch housing after the pigging sequence is complete. This can be time-consuming and tedious, relying on operator control. Removing the pig manually also has safety implications, for instance, if the pig isn’t handled hygienically or if it’s not reinserted correctly at the launch station.

In contrast, the HPS pig, at the end of the pigging cycle, automatically returns to its housing which enables fully automated operation and ensures high levels of safety, productivity, and operational efficiency. What’s more, the HPS pig can also be easily cleaned in place (CIP’d). That’s because HPS launch housings contain a special chamber for the pig, which is slightly larger than the pig. This enables water and cleaning fluids to be easily and quickly applied to the pig, ensuring sanitization and cleanliness. Here’s more about how HPS pigging systems clean pigs.

How Companies Get Around Using Single Directional Pigs?


Some companies get around the manual return of the pig by incorporating a pipework loop system at the end of the line to turn the pig around. However, the drawback of this is that it requires a substantial amount of pipework and valves so from a cost perspective it’s not an ideal choice.

Another route some companies have gone down is using routing stations to automatically return the pig back to its housing. As well as being expensive to purchase, routing stations are difficult (and expensive) to clean and maintain.

That’s why we strongly recommend, if considering a hygienic and sanitary pigging solution for your organisation, you choose a company that primarily supplies bi-directional pigs.

Avoid Pigs with Solid Magnets

As well as avoiding single directional pigs, it’s alshigh-performance pipeline pig o important to avoid pigs that contain solid magnets as they are a safety and contamination risk. Solid magnets are more susceptible to breaking free from the pig, shattering and contaminating the product which makes them unsuitable for hygienic and sanitary applications.

If magnetic material ends up contaminating the product, the entire batch will be rendered useable. This can be extremely costly for manufacturers in terms of lost product, lost production time, lost income and so on.

Instead of using solid magnets, HPS pigs contain a flexible magnetic silicone-based core. This is molded to the rest of the pig so it in effect becomes part of it. Unlike solid magnets, the silicone-based magnetic core will not shatter, fragment or break free from the rest of the pig. This improves safety and avoids the risk of contaminating the processed product. What’s more, the magnetic core is fully detectable and enables full PLC/software control and automation.

Navigating 1.5 D Bends

The other major problem with some pigs that contain solid magnets is that they lack flexibility which means they may struggle to navigate 1.5 D / 90-degree bends. To get around this issue, manufacturers may be forced to make unnecessary pipework changes and modifications. This is not only time-consuming but expensive too.

Some pigging companies also supply pigs without a magnet. However, the problem with pigs without a magnet is that the pig cannot be detected and controlled, which severely limits pigging system automation.

That’s why HPS food grade pigs contain a flexible magnetic core. This enables detection and PLC/Software control and automation. The flexibility also enables the pig to easily travel around 1.5 D bends while still efficiently recovering up to 99.5% of product.

Find Out More

So, how important is using bi-directional pigs for your pigging system? The answer is very!

HPS has been in business since 1995. That’s more than two decades of helping liquid processing companies bring the benefits of pigging and product recovery systems to their organisations.

If you choose HPS as your pigging provider, you can have the assurance that you’re working with a company whose products are trusted throughout the world. Not only are our pigs bi-directional, but they are highly efficient, robust, flexible and contain a magnetised silicone core that consistently outperforms other pigs in the market.

To find out more about high-quality pigs and pigging and liquid product recovery solutions for your organisation, please contact HPS!

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