Frequently Asked Questions
pigging systems faqs
Since 1995, HPS has been delivering reliable, innovative and effective liquid product recovery (pigging) solutions to organizations throughout the world.
Here are some of the more common questions we’re asked about product recovery and pigging. If you can’t find the answer to your question here, please contact us.
Why Do Companies Use Pigging Systems?
Companies that process liquids use pigging systems because they significantly increase process efficiency, effectiveness, productivity, profitability and environmental sustainability. This is through increased product yield, reduced waste, less downtime, quicker changeovers, and less chemical and water consumption.
For example, pigging systems can transfer residual product into the final package, rather than disposing of it, so increasing yields and plant capacity, while reducing product waste and saving time, money and resources. Similarly cleaning a pigged line is quicker and uses less water and cleaning chemicals, so reducing waste further and improving operational efficiency.
What is the Main Purpose of Pigging?
In the process industries, the main purpose of pigging is to remove and, most importantly, recover residual liquid that remains in a pipe after transfer from one location to another. It is also used to reduce contaminations risks, speed up changeover times, increase plant capacity and improve safety.
How Does Pigging Work?
In its simplest form, a pigging system consists of a flexible projectile with a diameter slightly larger than the pipeline that needs pigging. Water, other liquid, compressed air or gas, or even the product being processed is then used to propel the pig through the pipe and remove or recover the remaining product. For an overview of pigging, please see What Is Pigging.
What is a Pipeline Pig?
A hygienic or sanitary pipeline pig is a specially-designed, flexible projectile, slightly larger than the diameter of the pipe it is cleaning, which pushes a product through a pipeline.
HPS pigs are made from materials that meet the requirements of FDA regulations (one of the reasons they’re ‘hygienic’ or ‘sanitary’). We also provide solvent resistant designs. They are ‘full contact’ which means they clean constantly, even when travelling around corners. These are tough yet flexible and extremely effective; product recovery is typically up to 99.5%.
What Types of Products Use Pigging During Production or Processing?
Just about any liquid or wet product that can be pumped can be pigged. This includes very low and very high viscosity products. HPS has successfully designed, implemented and commissioned pigging systems for products including food, pet food, confectionery, soft drinks, water, wine, beer, spirits, shampoos, conditioners, body wash, bubble bath, toothpaste, deodorants, hairsprays, detergent cleaners, chemicals, paint, pharmaceuticals and many more
Can Pigs Travel Through Pipe Bends?
Yes. The flexible nature of HPS pigs enables them to travel through 1.5 D – 90° bends and still maintain full recovery rates.
Can HPS Pigs Withstand High Temperatures?
HPS pigs will withstand temperatures up to 250 °C or 482 °F without degradation. This means you can steam clean them if required.
What’s the Difference Between Hygienic Pigging and Sanitary Pigging?
Hygienic pigging systems and sanitary pigging systems are actually the same thing. Generally, people in the UK, Ireland and elsewhere that mostly speak British English, tend to refer to hygienic pigging systems. In the US, Canada, Australia, New Zealand and some other countries, people are more likely to refer to sanitary pigging systems. There’s no hard and fast rule though; the words hygienic and sanitary are sometimes used interchangeably.
What do the Initials HPS Stand For?
HPS stands for Hygienic Pigging Systems. That’s the original name of our company. A lot of people refer to us as plain HPS because it’s easier to say. We’re happy with that. We’re also known as HPS Product Recovery Solutions because product recovery is the proper name for pigging.
How Much does a Pigging System Cost?
Because there are many different variables involved in working out costings, it is not possible to provide standard pricing. However, here is an article on pigging system pricing and how to find out how much a pigging system costs. Pigging systems deliver a high return on investment and usually pay for themselves in less than a year.
How Long Does a Pig Last?
HPS pigs are robust, reliable and specifically designed to provide as long a working life as possible. However, the actual lifetime of a pig depends on the process, pipe material, products being pigged and so on. When you contact HPS about a pigging solution for your organisation, our experts will be able to advise you on the expected lifetime of your pigs. As a guideline, HPS pigs are usually guaranteed for 30 kilometres or 18 miles of use.
How Does a Pig Enter and Leave a Pipeline?
All pigging systems need a method of introducing the pig (or pigs) safely in to the line and getting it out of the way when it’s reached its destination. This is the key function of pig launchers and pig receivers.
Do I Need To Manually Load or Remove the Pig?
Because most HPS pigging systems are fully automatic, there’s no requirement for the operator to manually remove or load the pig. Usually the only time you’ll need to manually access a pig is for inspection and maintenance.
What Propels a Pig Through a Pipe?
Pigs don’t propel themselves, they are pushed along pipes by liquids or gases. There is a range of different propellants used in industrial process pigging, including water, filtered air, nitrogen, carbon dioxide and other products.
How Fast Do Pigs Travel Through Pipes?
The HPS research team has measured the average speed of an HPS pig at 40.56 mph, or 18.14 m/s. However, the speed at which pigs travel through pipe lines depends on the product, pressure, process, pipe diameter, pipe length and a number of other factors. Many people are surprised by how fast pigs travel through pipes. Most pigging operations last just a few seconds, sometimes even fractions of a second. This makes the whole pigging process extremely quick, minimising interruption to operations.
At What Stage in a Process is Pigging Used?
It depends on the process. Typically, an operator or automatic control system will send a pig through a pipe to recover product whenever required. This can be, for example, when a pump has emptied a holding tank, there’s a change of product, before CIP, or when a particular batch run is complete.
Can You Fit a Pigging Solution to Existing Pipework or Processes?
Yes. We fit pigging systems in existing pipeline processes, as well as new plants. Our engineers will design a custom solution that meets your precise needs and install it with minimal disruption to your business.
What Type of Pipework is Suitable for Pigging?
Usually the pipework in a hygienic pigging system is made of stainless steel with a highly polished internal finish. This ensures high levels of product recovery, sanitation and cleaning. It is however possible to pig systems which use other types of pipe materials, but we will need to discuss this with you. Whatever pipework your system uses, the infrastructure must meet certain criteria. Here is an article providing guidance on pipeline infrastructure for pigging.
Is Pigging Compatible with Clean In Place (CIP) Systems?
Yes. HPS Pigging Systems and Clean In Place (CIP) solutions are fully compatible. Because HPS pigs recover nearly all product within a pipe, CIP is much easier, less time consuming, uses less water and CIP chemicals, and is less labour-intensive. What’s more, HPS designs pigging systems to be fully compatible with CIP systems. This means that HPS pigs and other pigging system components (including specially designed HPS sanitary ball valves) can themselves be cleaned in place.
Can I Use a Pig Straight After a Hot Washout?
We do not recommend using an HPS pig immediately after a hot washout or clean in place (CIP) operation. Instead, allow the pig to cool before using it again. You can usually accelerate cooling by flushing the pig with water or suitable alternative cooling medium.
Are there Different Types of Pigging System?
Yes. We provide fully customised pigging solutions to meet the precise needs of each of our customers, so nearly every system is different. There are various types of pigging system available, however most hygienic pigging systems we supply fall in to one of three basic categories: single-pig systems, tank-drop off systems, or double-pig systems.
Can You Design Pigging Systems With Automatic Control?
While some simpler pigging solutions still use manual control, most pigging systems are either partly or fully automated. Automatic pigging solutions, controlled by PLCs with either HMI or SCADA systems, have a wide range of benefits. These include increasing process speed, productivity and overall efficiency. Automation also reduces the chances of human error and so increases safety.
What is the Minimum Pressure Needed to Pig a Line?
It depends on the system. However, the pressure needed to push the pig is typically lower than the product pumping pressure.
Where Does The Term ‘Pigging’ Originate?
The terms ‘Pigs’ and ‘Pigging’ are commonly used throughout industry. The most common reason given for the origin of the term comes from the oil industry. This is where metal discs connected by a rod were propelled through oil pipelines to remove the build-up of paraffin wax on the internal wall of the pipe. The action of metal on metal were said to have made a squealing noise like a pig. However there are other reasons given for the name ‘pigging’. One is that the letters are an acronym standing for “Pipeline Inspection Gauge”. Another is that pig simply refers to a solid object, in the same way as a ‘pig’ of iron or lead. Either way, the common term for the process of sending an object through a pipeline to recover product or clean the lines is called “Pigging”. Today, pigging products and services are the core business of HPS Product Recovery Solutions.
What Do I Do if a Pig Gets Stuck?
If you have an HPS solution, your pig will not get stuck! We specialise in pigging systems and have extensive experience in providing workable, efficient and reliable product recovery solutions. If a pig doesn’t reach its destination, there’s always a logical reason. Typical causes are lack of air pressure, pipeline faults, leakage from a pipe connection, or an obstruction such as a closed valve in front of the pig.
How Does a Pigging System Detect Pig Location?
HPS pigs have special properties that enable us to magnetise them. Our specially designed pig detectors, which fit to the outside of pipework, will detect the magnetised pig at either end of a line. These detectors are non-intrusive to the product line and can detect the pig’s magnetic field through stainless steel pipe. The detector signals are then used for tracking and control systems.
My Product or Process is Unique. How Can I Find Out If It Is Suitable for a Pigging System?
Many of our customers use specialist equipment, products and processes. If it’s a liquid, we can almost always design a system to pig it. Contact one of our experts to find out what is the best solution for your organisation.
How Long Does a Pigging System Take to Install?
There’s no clear-cut answer on how long a pigging system takes to install. That’s because every pigging system is unique and designed around the exact requirements and needs of each customer. However, as a general guide, a simple single-pig system with one launch and one receive return, the average installation time is around 2-3 days. This includes electrical, pneumatic and mechanical installation. Installation times for other types of solutions such as tank drops off systems would be slightly longer.
Our streamlined integration process means, regardless of the system, plant downtime is kept to an absolute minimum. We’ll also work around your schedule and minimise disruption to operations.
Does the Length of the Pipeline Determine the Installation Time?
No, installation time is determined by the amount of equipment being installed and the number of pipelines. The length of the pipeline has limited impact on the installation time.
Are all Pigging Systems Designed Hygienically?
Some pigging systems are not designed hygienically as in some cases it’s not required.
However, the majority of HPS pigging systems and components are designed hygienically which minimises cross-contamination risks and allows quick and efficient cleaning processes.
As well as providing hygienic solutions for the food and beverage industry, HPS also provide hygienic solutions to many more manufacturers. This includes the paint and coatings industry who are implementing hygienic pigging systems to reduce the risks of a microbial attack and the threat of contamination and product recalls.
What’s the Longest Pipeline Your Pigging Systems can Pig?
The team at HPS have a wealth of experience and expertise in installing long pipe runs. For example, HPS provided a pigging solution for an Australian bottling company and the process pig travels over 3000 ft (just under 1 km). HPS also provided a product recovery solution for a bottled water company located in Canada. The bi-directional pig travels over 1 km.
Regardless of the pipeline length, HPS hygienic pigs will not get stuck and will efficiently travel through pipelines and recover practically all of the product (up to 99.5%) from the pipe.
How Long Do Pigging Systems Last?
If properly designed by a pigging system expert and appropriately maintained, pigging systems will last an extremely long time. In fact, some of our very first systems are still in use after twenty years. That’s because HPS systems are highly effective, durable, reliable and long-lasting.
However, nothing lasts forever, so routine replacement of certain components such as pigs and seals will help extend the lifeline of your system. Pigging system maintenance is also essential to ensure your systems remains in prime condition and delivers optimum performance. At HPS, we recommend having a pigging system service plan which gives peace of mind and saves you money in the long run.
All pigging systems come with a warranty that lasts a year. In addition, the pig (or pigs) also come with a minimum usage guarantee of 30 kilometers or 18 miles of use (subject to terms and conditions). For many customers, we also offer pig usage software, which tells operators when the pig is nearing the end of its working life and needs replacing.
How Do You Get a Pig into an Automated System without Manual Intervention?
Automatic pigging systems are nearly always ‘closed loop’ systems that require no manual intervention. The pig resides in a special housing at a launch station (and sometimes a receive station), which allows the system to automatically introduce the pig to the line as and when needed.
As well as storing the pig (or pigs) when they’re not actually ‘pigging’, HPS launch housings are designed so that the pig can be cleaned and CIP’d without actually being removed. They are also designed so the pig can be introduced automatically into the process line as required by the pigging sequence.
Please note that even in automatic pigging systems, pigs need to be removed from time to time for maintenance and inspection.
I Still Have a Question About Pigging – Can You Help?
Of course! As well as being extremely good at what they do, HPS staff are a friendly bunch and happy to discuss any aspect of pigging or product recovery with you. Just give us a call, fill in one of the contact forms or drop us an email. We would love to hear from you!