How Does Pipeline Pigging Work?
Product recovery pigs (pipeline cleaning pigs) are sanitary projectiles that force the remaining product from pipes and tubes after production cycles. Designed for various products in the food, dairy, beverage, chemical, and home and personal care industries, silicone pigs are ideal for product recovery and pipeline cleaning due to good mechanical properties (elasticity, absorption, tear strength). Silicone also has good chemical compatibility with the majority of products.
Pipeline Pigging Systems increase product yields and reduce Clean-in-place (CIP) costs by recovering the residual product left behind in processing lines after cycles. Removal of leftover product also means a reduction in the time required to clean lines. The time, water, and chemical savings help offset the investment costs in the recovery system.
Pig is not the most intuitive name for the device, but before we talk about the origins of its name, we’ll discuss its design and function in product recovery.
Pipeline Pig design
Pigs act like a pipe-cleaning squeegee, but instead of being forced through the pipe on a wire, the pipe-cleaning action uses forced air, nitrogen, or water that pushes the projectile and product through the piping. Product may be pushed out through the end of the line or, when appropriate, back to the product holding tank.
Processing engineers specify projectile design based on:
- Product viscosity
- System line size
Four-wiper design is ideal for thicker, more viscous products or products that are difficult to clean and/or contain large particulates.
Tube OD |
Item Number |
Item Number |
Overall Length |
1.5 |
PR-P15-ASX |
PR-P15-ADX |
3.95" |
2 |
PR-P20-ASX |
PR-P20-ADX |
4.44" |
2.5 |
PR-P25-ASX |
PR-P25-ADX |
5.45" |
3 |
PR-P30-ASX |
PR-P30-ADX |
6.16" |
4 |
PR-P40-ASX |
PR-P40-ADX |
7.75" |
Eight wiper design provides greater flexibility and efficiency, with a range of applications.
Tube OD |
Item Number |
Item Number |
Overall Length |
1.5 |
PR-P15-BSX |
PR-P15-BDX |
3.95" |
2 |
PR-P20-BSX |
PR-P20-BDX |
4.44" |
2.5 |
PR-P25-BSX |
PR-P25-BDX |
5.45" |
3 |
PR-P30-BSX |
PR-P30-BDX |
6.16" |
4 |
PR-P40-BSX |
PR-P40-BDX |
7.75" |
Pipeline Pigging reduces product loss
If your current processing design results in wasted product that could be recovered, it’s easy to calculate the value of product recovery:
Unit cost X volume of loss per cycle X number of cycles per time period.
In the case of Center Fresh Egg Company, annual savings from product recovery reached nearly $46,000. They continuously produced liquid eggs that were loaded in batches into tankers for delivery. After each load, operators lost five gallons of product that remained in the lines. They collected the wasted product in buckets and carried it out for disposal, a process they repeated ten times per day. While breaking upwards of five million eggs per day for the liquid egg market, yield losses from their processing system design were adding up.
The company had used a traditional air-blow system for product recovery, but air alone couldn’t recover very much product. Air blow systems typically core through product instead of recovering it.
COST OF GOODS WASTED
- 8.6 (pounds per gallon of liquid eggs) x 50 gallons per day = 430 pounds of wasted product per day, or $176.30
- 430 pounds x 260 workdays = 111,800 pounds per year X $.41*/pound = $45,838. (Read the Case Study).
*Egg prices vary on a daily basis. See USDA for current pricing.
Pipeline pigging systems are particularly beneficial to producers that run any sticky, thick, or viscous products regularly. The higher the product viscosity, the greater the amount of leftover residue. With less product to remove after pigging, cleaning is more effective and efficient.
When dedicating a separate line to each product isn’t realistic, product changeovers add production downtime, so efficient cleaning translates to more production uptime. While not as common, some processes allow a product changeover without the need for CIP cleaning, so sending a pig to clear the line is sufficient.
You can add a product recovery system to new or existing pipeline processes. Design engineers can tailor solutions to precise needs based on your processing variables.
Quick returns
Installation can take place with minimal disruption to normal processes. Process engineers can assist in assessing existing lines for potential obstacles to product recovery, such as welds and dents, and determine the potential impact of valves or instrumentation in line and size transitions that can affect recovery.
Depending on the design of the system control box, operators can be trained and running the system almost immediately.
Plants typically see a return on investment in six months to a year based on product recovery and savings on cleaning.
Basic One-Way System
During a basic one-way system, the projectile reaches the sensor at the end of the piping and the control panel automatically turns off the air. Then, an indicator light illuminates and the projectile can be removed from the catcher.
During an automated return cycle, operators need not remove the pipeline pig from the catcher at the pipe outlet; instead, they activate a return cycle on the system control screen to return the pig back to the launching location. Operators can then remove the pig from the launching location for inspection.
The product recovery projectile should be checked after each use for cracks or tears, which can be caused by product or pipe surfaces. Replacing cracked or torn projectiles ensures better product recovery and cleaning.
Automatic Return System
The automated return package is well-suited to hard-to-reach or distant catch locations.
Operators should check the pipeline pig after each use for cracks or tears, which can be caused by product or pipe surfaces. Replacing cracked or torn projectiles ensures better product recovery and cleaning.
Reduce Water Waste & Use
More efficient cleaning saves water and reduces hazardous chemical usage. Pipeline pigging systems for the food industry offer significant benefits for environmentally conscious producers.
Why is it called a pig?
Some claim pig is an abbreviation for Pipeline Intervention Gadget or Pipeline Inspection Gauge.
Others say pipeline pigs that used to be equipped with leather seals squealed like a pig as they moved across the interior pipe surface.
Air Flow Requirements
For smooth operation, the product recovery control system's air pressure and airflow settings can vary depending on factors such as product viscosity and system backpressure. The following pressure and flow settings are the recommended settings for the initial startup of your system.
Adjustment of these settings may be required to achieve the appropriate performance for your application. To learn more, see the Product Recovery System Installation, Operation, and Maintenance Manual.
Design/selection considerations
Engineers consider several key factors when designing or selecting a product recovery system that operates consistently and efficiently:
- Pressure requirements for moving the pig through piping
- Product variables that can affect pressure requirements, such as viscosity and density
- Ability of the pig to move through the piping layout
- Clean-in-place requirements
- Ease of maintenance
- Availability of automatic and manual controls
Built-in Safety
One important aspect of a product recovery package is operator safety. Control units should include safety features such as air lockout and emergency stop capabilities, system timeouts, and automated pressure relief.
The modern pipeline pig works right out of the box
Pipeline Pigging systems used to require extensive trial and error before new systems were properly tuned, with some customers abandoning recovery projects because of frustration and system failures. In contrast, modern product recovery control systems come pre-configured for each application and operate successfully right out of the box.
They are an effective solution for a variety of applications:
- Processed Foods
- High-Acid Foods
- Dairy
- Beverages
- Brewery
- Home & Personal Care
- Chemical
Next Steps
A product recovery system from TrueClean® will increase your product yields and reduce clean-in-place (CIP) costs by recovering the residual product left behind in the lines after your process. This means you should see a reduction in the amount of time it takes to clean these sections of line. In many cases, the time, water, and chemicals saved offset the cost of the system.
TrueClean's Product Recovery Systems are simple to operate and can easily be integrated into your existing system. Choose from our manual, basic, or automated return packages.
ABOUT CSI
Central States Industrial Equipment (CSI) is a leader in distribution of hygienic pipe, valves, fittings, pumps, heat exchangers, and MRO supplies for hygienic industrial processors, with four distribution facilities across the U.S. CSI also provides detail design and execution for hygienic process systems in the food, dairy, beverage, pharmaceutical, biotechnology, and personal care industries. Specializing in process piping, system start-ups, and cleaning systems, CSI leverages technology, intellectual property, and industry expertise to deliver solutions to processing problems. More information can be found at www.csidesigns.com.