Pigging Systems for Hygienic, Sanitary and Process Environments

Hygienic (sanitary) pigging systems nearly all the residual liquid product from pipelines that would otherwise be wasted.

The technology is in wide use in a variety of different industries and sectors that pump liquids. This includes sanitary, hygienic and process environments such as food and beverages, confectionery, personal care, cosmetics, paints, coatings, pet food, household liquids and many others.

Regardless of the application, pigging systems deliver a wide range of tangible benefits and a high return on investment (ROI).

While aims and objectives vary between companies, some of the key benefits of pigging include increased yields, reduced waste, improved efficiency, increased capacity, less downtime, faster changeovers, decreased costs, better environmental sustainability plus much more.

Custom Pigging Systems – Designed Around Customers’ Exact Requirements

Also referred to as ‘liquid product recovery’, pigging systems can be implemented into existing plants and pipework, as well as included as part of new installations.

Because nearly every processing plant is different, so is nearly every pigging system. That’s why HPS pigging systems are designed around the exact needs, aims, and objectives of each customer.

However, in liquid processing, there are many different configurations of pigging systems to achieve different goals within your processes. Some of these are specific to HPS (because we are experts in liquid product recovery and pigging, so we’ve made many innovations over the years!).

Some of the different configurations of pigging system include:

    • Single-Pig Pigging System
    • Double-Pig Pigging System
    • Tank Drop off Pigging System
    • Dual Pigging System

In this blog, we take you through the different types of pigging systems configurations so you can choose a pigging solution most suitable for your specific application.

HPS pigging demo room equipment

Single-Pig Pigging Systems

Single-pig pigging systems are one of the most popular types of liquid product recovery systems. They also tend to be the simplest, and most cost-effective type of pigging system.

This type of pigging system is most suitable for simple processes that pump a liquid or wet product from a single source to a single destination. Having said that, there are also different configurations of single-pig systems, including different launch configurations, single source to multiple destinations, or multiple sources to single destination.

The pigging system usually includes a pig launch station and a pig return station. In this system, the normal position for the HPS pig (the specialist projectile that travels along the pipes or tubes to transfer residual product) is in its housing at the launch station.

The single pig system is used with an extensive variety of products including food stuffs, chocolate, liquid detergents, toothpaste, pet food, beauty products, soft drinks and so on. However, this type of system isn’t suitable for extremely complex processes, as well as products susceptible to foaming and aeration issues i.e., beer, and wine.

Whatever your goals, the single-pig system can be designed as a semi-automated or fully-automated system. However, we strongly recommend that you consider choosing a fully-automatic pigging system to ensure maximum levels of efficiency, reliability, and safety.

How Does the Single-Pig System Work?

Following the product transfer sequence, the HPS pig is safely introduced into the pipeline via the pigging launch station using a suitable propellant.

The HPS pig recovers nearly all the product from the pipe and forces it to its destination (typically a filling machine or another storage vessel for the product).

The next stage sees propellant introduced at the receive station to return the pig back to its housing.

This type of pigging system can be installed to recover residual liquid to the filler/destination tank or to send product back to the source tank.

Single-pig pigging system

Double-Pig Pigging System

Double-pig pigging systems are another type of pigging system often (but not exclusively) used with processes where the product must not come into contact with air during processing.

This is either because air contact may degrade the product, i.e., increasing the dissolved oxygen content in wine or for certain products, it may cause foaming or aeration. If this happens during processing and production, it can cause delays, and in some circumstances, may render the product unusable. Therefore, the double-pig pigging system is commonly used with products such as beer, wine, and foam gel products.

In regard to automation, the double-pig system is suitable for semi or fully automated operation. However, in most cases, the systems supplied by HPS are nearly always fully automated.

How Does the Double-Pig System Work?

As the name suggests, the double-pig system uses two pipeline pigs. The first pig’s role in a double-pig system is to precede the flow of product being recovered, typically to avoid air contact and minimise foaming or oxidative degradation. The second pig’s role in the system is to clear the pipe, recover residual liquid and transfer product safety and efficiently.

With the single-pig systems, the pigging sequence begins after the transfer of product has been completed. However, this is not the case for double-pig system.

Instead, before the product transfer sequence, a pig is sent to the outlet of the pump to reduce the air in the line. The HPS pig acts as an interface and creates a seal between the product and air within the line. So, this prevents air from coming into contact with the product and prevents aeration and foaming.

Following this, product is transferred into line behind the pig. This pushes the pig to its destination where the pig re-enters its housing. Following the completion of the product transfer sequence, the second pig then recovers nearly all the product from the pipe and forces it to its destination.

HPS double-pig pigging system

The Tank Drop Off Pigging System

The tank drop off pigging system is another type of product recovery system suitable for processes with multiple product destinations.

This type of system is fairly similar to the single-pig pigging system. However, instead of a single destination, the tank drop off system features multiple destinations on the same line that the pipeline pig can recover residual product to.

The tank drop off system can be used with an extensive variety of products including sauces, dips, washing up liquid, and chemicals to paints, solvents, and lubricants. Because there is no limit on the number of tank drop-offs that can be used, this type of pigging system is suitable for more complex processes.

For optimum levels of efficiency, reliability, and safety, the tank drop off system is best suited for fully automated operation.

How Does the Tank-Drop Off System Work?

Following the transfer of product to a tank, a pig will be introduced into the line automatically to the blocking valve for that tank. Any blocking valves between the destination and the pig are opened to allow for a clear route.

The HPS pig is propelled through the pipe and recovers nearly all the product into the tank. Following this, the pig is then returned with the same receive-return pigging station used on a single-pig system.

tank drop off system

The Dual-Pig Pigging System

The dual-pig pigging system is another configuration of pigging system which was originally designed by HPS for a customer that manufactures paint and coatings.

Although it uses two separate pigs like the double-pig pigging system, this type of system is suitable for more complex processes with a cleaning solution between the two pigs. It offers dual cleaning capability and optimises the volume of solvent or water required to achieve pipe cleanliness.

Although the dual pigging system was originally designed for paint and coatings applications, it can be used with a wide variety of applications that require a cleaning solution combination between the pigs, from food and beverages to lubricants and household liquids.

For increased process speed, productivity, efficiency, and safety, the dual-pig pigging system is suitable for semi or fully automated operation (although we strongly advise on fully automated).

How DOES the Dual-Pig Pigging System Works?

The dual-pig pigging system uses two separate pipeline pigs. The pigs are injected into the line with a measured “slug” of either solvent or water between the two pigs.

The “product-pig-cleaning solution-pig” combination is propelled to the destination, recovering the residual product while flushing the line with the water or solvent product that is between the two pigs.

dual pig pigging system

Importance of Choosing the Right Pigging Provider

There are many different configurations of pigging system. Whether you’re planning a simple single-pig pigging system or even a more complex PLC-controlled tank drop off system, before you can start choosing a pigging system, you need to ensure you choose the right pigging provider.

Your chosen pigging provider must be able to understand your processes and advise on the most appropriate system tailored to your precise requirements.

In addition, by making sure you choose a pigging system from an expert in pigging and liquid processing, with extensive experience and a proven track record, will go a long way to helping ensure the success of your project.

Find Out More

To find out more about the different configurations of pigging systems, including a bespoke design to meet your precise requirements, or have any questions, please don’t hesitate to contact us:

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