Maintaining Hygiene During Pipeline Product Recovery
Firstly, if you’ve landed on this page and are looking for information on cleaning “sus scrofa domesticus” (domestic pigs – as in the animals), then this is not the right page for you. This article is about pigs used in liquid product recovery (pigging) systems. These types of pigs are projectiles propelled down pipes to remove residual product, instead of wasting it.
The reason companies use pigging systems is because they save them a lot of money and make them more efficient. Pigging is also good for the environment.
If you’re interested in the benefits of pigging, or you want to know why the process is called pigging and where the term originates, there’s more information in our FAQs section.
Keeping The Pig Hygienically Clean During Liquid Processing
Here’s a question recently asked by a company interested in our systems. They were chatting to one of our official HPS agents about potential pigging solutions. This particular company manufactures dairy products, so, like many other companies, they need to maintain high levels of hygiene throughout their processes. And, while they understood the concept of pigging, along with the benefits of it, during the conversation they asked how we keep the pig hygienically clean during the process.
What was also important to them was to use the smallest amount of cleaning fluid as possible, because the cleaning agent they use is expensive. And at the same time they couldn’t risk any chance of bacterial or cross-contamination.
Variety of Options
It’s actually a good question. Like many dairy product and other food and beverage manufacturers (as well as other industries like paint and personal care products), they spend a lot of time and focus ensuring all processes are sanitary. This stems right from the design stage through to cleaning routines and operator training. So, it’s important not to jeopardise hygiene at any point and in any way.
The first reassurance we give is in our company name. HPS stands for Hygienic Pigging Systems. And we’ve been providing pigging technology to companies throughout the world for a long time (since 1995).
Because nearly all HPS pigging systems are designed specifically for each customer, there are a number of options on how to clean a pig. Which option is best varies between systems. However, here’s a brief overview of one of the most common ways we ensure pigs stay hygienically clean in product recovery systems.
Uniquely Designed Pig
The unique design of HPS systems enable the pig to be cleaned in place (CIP’d). A pig rarely needs to be removed from the system except for occasional maintenance, inspection or replacement. As well as delivering extremely high product recovery levels (typically 99.5%), HPS pigs can be steam cleaned up to 250 degrees centigrade or 482 Fahrenheit, and this won’t affect their performance. They are also made from FDA approved materials, and are resistant to the cleaning chemicals normally used in processing foods, beverages, as well as non-food products such as paints, cosmetics, personal care goods and so on.
HPS pigs can be cleaned using the majority of CIP chemicals that are commonly used in the process industries. And, because some of these chemicals can be expensive, we usually design our systems so that only a small amount of these chemicals are required (delivered in short pulses if necessary) to clean the pig effectively. What’s more, it is also sometimes possible to save this chemical for re-use.
Cleaning Process Pigs?
As stated previously, how an individual system cleans pigs depends very much on the individual system. That’s because, not only are HPS systems bespoke to the individual process, but there are also a variety of different types of pigging system. These include, for example, single-pig systems, double-pig systems, dual-pig systems, multi-tank drop-off pigging systems, and so on.
But one thing nearly all our systems have in common is that the launch housings (and sometimes the pig-receive and return stations as well), have a special chamber for the pig. This chamber, as shown in the diagram, is slightly larger than the pig. This larger size enables water and cleaning fluids to be applied to it, fully washing and sanitising the pig.
CIP and pigging go hand-in-hand. We can often clean the pig as part of the same CIP process that cleans the lines. Or, using specially placed valves, create a circuit when required that only cleans the pig. The benefit of this is that it only needs small amounts of chemicals, and it’s also quick.
In addition, even though it only requires small amounts of cleaning chemicals, we can also add a valve so the chemical is sent to a storage vessel for re-use rather than drain, saving even more time and money.
Pig Cleaning Circuit
Referring to the drawing, let’s assume the main process line (which can be pretty long) has been initially flushed with water. The CIP process continues, and it is now full of cleaning fluid. Shutting off a valve at the pig receive and return station (this valve isn’t shown on the drawing), means the main process line stays full of liquid.
With the automatic 2-way piggabale valve open, there’s a short and efficient route to clean the pig in the pig housing. So, when the pump delivers cleaning chemicals, instead of travelling through the main process line (they can’t, because it is full) they travel through the pig chamber, surrounding and cleaning the pig on their way. The CIP process then continues. It could include pigging the main line to remove and recover the cleaning chemicals, followed by a water flush if necessary, before normal processing resumes.
The pig cleaning process, as demonstrated, is usually integrated within the wider CIP process and usually performed automatically as required. The pig cleaning part, while using minimal amounts of chemicals, which if necessary can be applied in short pulses. The chemicals can either go to drain, as shown in the diagram, or, with the addition of a further valve, the system could send the previous flush water to drain and the CIP chemical to a collection vessel. This means the company can reuse the cleaning chemical as appropriate. If the chemical is expensive this saves it rather than flushing it to waste.
So, maintaining the pig in a sanitary state is quick and inexpensive. The bulk of the cleaning fluid is used when cleaning the main process line, and this applies whether or not the process incorporates pigging.
Find Out More
If your company processes liquids in hygienic (sanitary) environments and you need to produce more for less, and faster, please fill out the short form below and one of our friendly, knowledgeable team will email you (or phone you if you prefer – just let us know).
Or, if you are just interested in pigging, make sure you check out our pigging system resources page and please get back to us with any questions.