Double-Pig or 2-Pig Pigging System

How Does Double-Pig or 2-Pig Pigging System Work?

1.The pigs run in reverse direction to empty the pipe.

Different from single-pig pigging system, for double-pig system, the pipeline pigs are separated at first, that is, the product drives the first proceeding pig to the next pig station, like the pig stopper or the receiving station. At this time, the pipe is full of product, the valve at the tee is opened to let the product flow out, and the pump continues to pump product into the pipeline, after completion, the two pigs move in opposition direction, and empty the pipeline completely. Finally, both pigs return together to the launching station, the pigs have to move forward and backward, they are bi-directional pigs.

Double-pig pigging system PID

2. Carrying solvent or cleaning agents between the two pigs.

Sometimes double-pig pigging system (2-pig system) is also used for process, like paints and coatings production, where the pipeline has to be cleaned by solvent or cleaning agents to prevent cross -contamination. There is some special solvent or cleaning agents, at a distance of 2-3cm, between the two pigs. The propellant is used to drive the 2 pigs back and forth until the required cleanliness is achieved.

3. Prevent product from contacting with air

The double pig pigging system is usually applied to the process where the liquid product must not contact with air. Once contacting with air, the dissolved oxygen content in the product becomes high, and the product may become spoiled.

As shown in this video, before product transfer, the first pig is pushed to the receiving station to minimize the air in the pipeline. The pig works as a seal to block the outlet, and prevent the product from contacting with the air, otherwise it may gets oxidized. Then, the product begins to be transferred to its destination behind the first pig. When product transfer is complete, the second pig starts to push the residue product inside the pipeline into the destination just the same procedure as single-pig pigging system.

4.The transfer and pigging of different products in the pipeline at the same time

In double-pig pigging system, after the first product transfer is complete, the first pig driven by propellant, begins pigging until it reaches the furthest pig stop and is blocked. After this pig, a second product is also pumped into the pipeline until the end of product delivery, the second pig starts pigging until it reaches the pig stop, it is blocked. After the second pig, a third product can be transported into the pipeline, the whole process can greatly improve production efficiency.

Double-Pig System Introduction

In a double pig system, two pigs with or without intervals move in the same direction or in opposite directions in the pipeline. The double-pig system is composed of a pig launcher, a pig stopper, 2 pigs, and a receiving station. The pig launcher is the home base of the pigs, it can contain 2 pigs. In the initial stage, two pigs can be placed in one station, or one at each station.

The double pig pigging system is applied to paints, coatings, wine, foam gel , chemicals, cosmetics, food, beverage, and so on.


  • Carrying detergent or solvent (e.g. water) between two pigs running back and forth in the same direction
  • A pig placed in front of the product can reduce foam generation, especially for pipes with downward slopes
  • In the same pipeline, product A – pig 1 – product B – pig 2 – propellant, this process is also called “batch pigging”
  • The entire pigging process can be repeated according to the requirements for cleaning
  • Gas propellant is compressed air, liquid propellants are water, detergent or products.
  • Fully automated controlled
  • For multiple products and frequent product changes, large quantities of cleaning agents and corresponding preparation and operation time are reduced
  • Automation and maintenance-free operation can largely reduce operating errors, and labor costs
  • Reduce or no payment for sewage treatment fees caused by detergent contamination
double pig system
Hyperfore double-pig system
ISO 1″2”,2.5”,3”,3.5”,4”,5”,6”
MaterialStainless Steel304,316L for parts contacting products
Pressureless than or equal 0.8MPa
Polishing OR<Ra1.6,ID<Ra0.8,ID<Ra0.375
Temperatureless than 150°C
Pig driving Pressure less than or equal 0.2MPa normally
Double pig pigging system specifications

The above table shows the general technical specification for Hyperfore double-pig pigging system.

double-pig system launcher
Double pig system launcher
  • The launching station have a length of two pigs that can be arranged one behind the other
  • Sanitary design, no dead corner for cleaning
  • Two pigs can be placed in one station, or one in each station, at the beginning
  • CIP & SIP
  • Type: automatic launching station
  • Stainless Steel 304, 316L for parts contacting products
  • Connection type: flange, clamp, welding
  • ISO1″-ISO6″, DN25-DN150
  • Durable, high quality
  • Type: automatic receiving station
  • Hygienic design, no dead corner for cleaning
  • No residue liquid left
  • CIP &SIP
  • 316L for parts contacting with products
  • Sealing:EPDM, VMQ, NBR
  • Connection type: clamp, welding, flange
  • ISO1″-ISO6″,DN25-DN150
Double pig system receiver
Double pig system receiver
  • Hygienic and aseptic design
  • Placed side by side in the launcher
  • Pigs can be cleaned in line
  • Permanent magnet inside, easily to be located
  • Smoothly passing through 3D bends
  • Cleaning effect more than 99.5%
  • Applicable to paint, coating, wine, foam, beer, gel, chemical, chocolate, food, etc.
  • Available in different materials: FKM, FPM, EPDM, VMQ, POK, etc.
  • DN50-DN150, ISO2″-ISO6″
Pigs for double pig system
Pigs for double pig system
pig stop
Pig stop
  • Allowing the liquid to pass through while blocking the pig
  • Pigging liquid products into different destination tanks
  • Hygienic design, more hygienic than piggable ball valve
  • Connection type: welding
  • Stainless Steel 304, 316L for parts contacting products
  • DN25-DN150,ISO1″-ISO6″

What’s More about Double-Pig System or Single-Pig System?

If you are in industries like coatings, paints, gel, foam, wine, brewery, you may be interested in our double-pig pigging system.

Frequently Asked Questions
double pig system launcher
Double pig system launcher

Double- pig system is pigging system with 2 pigs. The launcher can hold 2 pigs side by side. Combination of 2 pigs together, ensure a physical barrier between different fluid products. There can be some solvent or cleaning agents between the 2 pig combination, this kind of pigging process can be applied to paint, coating, chemicals to remove the special product stuck to the inner wall of the pipe. 2- pig pigging system can also be applied to process where the product can’t contact with air. The function of the first pig is to remove air from the pipe.

double- shoulder pig
Double-shoulder pig

Several factors may affect the lifespan of a pig:

  • Installation condition of pipeline affects the life of a pig
  • The traveling speed along the pipeline affects the life of a pig
  • The product friction affect the life of a pig
  • The propellant pressure affect the life of a pig
  • The pigging frequency affect the life of a pig
  • The type of bends affect the life of a pig, 3D bends are recommended
  • Dry pipeline inner wall will do harm to a pig
  • Cleaning and maintenance affects the life of a pig
Automatic  launching station
Automatic launching station
Manual launching station and manual receiving station

Hyperfore manual product recovery system includes a manual launching station, a manual receiving station. Nevertheless it is a econimical and efficient sanitary pigging system.

Automatic launching station and automatic receiving station

It is suitable for hygienic application. Such as in food, beverage, dairy, chocolate, candy, cosmetics, shampoo, detergent and other industries. Components of our hygienic automatic product recovery system are automatic launching station, automatic receiving station,etc. Another key point, it can recover more than 99.5% of the residual liquid during pipeline pigging.

Automatic sterile launching station

It is suitable for industries with strict requirement for hygiene. For example, dairy products, wine, beverages, medicine and biotechnology industries. Hyperfore sterile product recovery system can be cleaned by CIP and SIP. The design of its launching station makes the whole product recovery system reach sterility level. That is to say, it is safe and reliable.

Double-pig launching station

Double-pig launcher is used for double-pig pigging system. It can contain 2 pigs placed one by one. In a double pig system, two pigs with or without intervals move in the same direction or in opposite directions in the pipeline. Cleaning process with a small amount of solvent is applied only in double pig systems.

A single-pig pigging system is a pigging system with one pig. A single-pig system can be applied in different processes, like pigging from single sauce to single destination, pigging from multiple sauces to multiple destinations, pigging from single sauce to multiple destinations. Hyperfore single-pig system and double-pig are both hygienic design, and can be implemented in a wide range of fields.

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