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A pigging evolution

04 December 2023

Peter Elgar explains how modern automated pigging systems can offer some impressive product recover benefits – reducing product waste and increasing yields.

Everything from sauces, dips, ready meals, chocolate, meat slurries and pet foods through to soft drinks, juices, wines and spirits could employ modern pigging technology– or liquid product recover technology – in their production. 

While it has been widely used for many years, the technology has developed a lot over time and pigging has changed from being a basic, sometimes clunky manual process, to being a fully automated, integrated high-performance advanced liquid product recovery technology. 

Just about any process which transfers liquid products through pipes, can potentially reap major benefits from the adoption of state-of-the-art pigging systems and we are seeing its use increasing because of its ability to makes significant productivity, operational and efficiency improvements. How? Pigging recovers the product from pipelines during batch changeovers that would otherwise be downgraded or flushed to drain or waste treatment. By doing this, it massively reduces changeover waste, while increasing yields and capacity, saving energy and reducing the quantity of   flush water and clean in place (CIP) chemicals required. It also makes changeover times much quicker and less resource-intensive. 

And as well as increasing profits, lowering costs, and delivering a rapid payback and strong ROI, it also increases environmental sustainability. 

Modern pigging work by propelling a specialist projectile (the ‘pig’) through a pipeline during batch changeovers. The pig has an interference fit with the inside diameter of the pipe, so transfers nearly all remaining product to the process destination. 

Without pigging, the remaining product would be lost to flush waste.

Pigs are propelled by filtered compressed air, nitrogen, CO2, water, sometimes the next product, or a combination of propellants.

The pigging operation itself is extremely quick, and product recovery rates are high. High-end pigging systems can typically recover over 99.5% of product from full lines. 

Importantly, modern pigging systems are nearly always fully automated – mainly for operational efficiency reasons but also for safety. 

Different system types
There are many different types and configurations of pigging systems, from basic single-pig systems, which literally transfer the product to its destination, and then the pig returns. Double-pig systems are also available, where the sequence of pigging is such that the two pigs prevent the product from coming into contact with air (important with wine, for example).

Then there are also multiple-source, multiple-destination and tank drop-off systems. 

A more recent innovation is the dual-pig system, specially designed to combine product recovery while optimising the CIP process.

The high return on investment and payback calculations usually make a strong business case for pigging technology, with figures that speak for themselves. 

For example, awn soft drinks manufacturer has saved the equivalent of around 48,000 cans of its product every week by pigging – a yield increase of around 4%, while a food ingredients manufacturer uses one system on a 900ft line and recovers 1,200 gallons of product at every batch changeover. 

One of the barriers to the adoption of pigging technology is that, occasionally, there’s an outdated perception that it’s a basic, manually operated technique. While that may have been true for some systems years ago that it is rather like comparing the unwieldy mobile phones the size of a brick we used to own, to the sleek smart devices that we all carry in our pockets today! Pigging is a technology that has advanced significantly in recent years

Peter Elgar is Director at HPS Product Recovery Solutions.


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