Requirements for Hygienic Pigging Systems
When planning a product recovery project, there are several factors to consider as part of the pigging system design, including the type of pig, system configuration, pig detection, automation and controls.
However, one of the most important considerations is the pipeline itself.
Many existing process pipelines can be adapted for pigging, but their suitability depends on factors such as the internal diameter, condition, layout, bends, valves and fittings. The product being transferred and the services available on site must also be considered.
This guide explains the main pipeline infrastructure requirements for a hygienic pigging system and how existing process lines can be assessed and prepared for successful pigging.
Can an Existing Pipeline Be Pigged?
In many cases, yes. The key requirements are a consistent internal bore, suitable bends and valves, good-quality welds and enough space for launching and receiving equipment.
What Makes a Pipeline Suitable for Pigging?
For a pig to travel reliably through a pipeline and recover product effectively, it needs a clear and continuous path.
A suitable pipeline will generally have:
- A consistent and accurately known internal diameter
- A smooth internal surface
- Suitable bends and fittings
- Minimal intrusion from welds and gaskets
- No damage or significant distortion
- Piggable valves throughout the proposed route
- Adequate support to prevent movement
- Enough space for the required launch and receive equipment
Many existing pipelines already meet most of these requirements. Where improvements are needed, individual components or sections of pipework can often be modified or replaced to create a suitable pigging route.
Pipe Diameter, Material and Standard
The internal diameter of the pipeline is particularly important because the pig must maintain contact with the pipe wall as it travels through the line.
It is the actual internal diameter, rather than simply the nominal pipe size, that must be confirmed. Different pipe schedules, standards and wall thicknesses can result in different internal dimensions, even when the stated pipe size appears to be the same.
The pipe material and applicable standard will also need to be identified. Process pipelines may be manufactured to ASME, ANSI, ASTM, BS, ISO, DIN and other standards.
Hygienic pigging systems are commonly installed in stainless-steel process pipework with a suitable internal finish. Other materials may be possible, but their condition, compatibility and suitability must be assessed as part of the system design.
Does the Pipeline Need a Consistent Internal Bore?
Changes or restrictions within the pipeline bore can interfere with pig travel and may damage the pig.
Areas to assess include:
- Changes in internal diameter
- Misaligned pipe connections
- Welds protruding into the bore
- Intrusive gaskets
- Instruments projecting into the pipeline
- Valves that do not provide a clear path
- Dents or damage to the pipe wall
These features are not always visible from the outside. Pipeline drawings, component specifications and, where necessary, a physical inspection can confirm the condition of the internal bore and identify any improvements needed.
Pipework Condition
A well-maintained pipeline provides the best conditions for safe, reliable pig travel and effective product recovery. As part of the assessment, the condition of the pipework and internal welds will be checked to confirm that the pig has a smooth, continuous route.
If any dents, distortion, intrusive welds or unsuitable sections are identified, these can often be repaired or replaced as part of preparing the pipeline for pigging. This helps ensure reliable system performance and protects the pig as it travels through the line.
Can a Pig Travel Through Pipeline Bends?
The flexibility and shape of HPS hygienic pigs enable them to travel through correctly designed bends while maintaining contact with the internal surface of the pipeline.
This means HPS systems do not require specialist bends. However, the pipeline should still be free from dents, damage, protruding welds and other internal obstructions that could interfere with pig travel.
Are Existing Valves Suitable for Pigging?
Valves within the pigging route must provide a clear, unobstructed path for the pig while allowing unrestricted product flow. Some standard process valves contain internal components that prevent the pig from travelling through them. For example, the disc inside a butterfly valve obstructs the pipeline bore.
During the assessment, HPS will review the type, size, position and internal design of each valve. If any valves are unsuitable, they can be replaced with appropriate piggable alternatives.
HPS will support you every step of the way, from assessing your existing valves and pipeline layout to recommending the most suitable solution for reliable pig travel, effective product routing and maximum product recovery.
Ensuring Correct Gasket Installation
Correctly selected and installed gaskets help maintain a smooth, consistent internal bore for reliable pig travel. The right gasket type, alignment and tightening procedure prevent the gasket from protruding into the product path.
An intrusive gasket can:
- Restrict or prevent pig travel
- Damage the pig
- Trap residual product
- Create a potential contamination risk
Rest assured, HPS will assess the pipeline connections and advise on the most appropriate gasket type, alignment and installation to help prevent intrusion into the product path.
Tri-clamp connections are widely used in hygienic processing and are suitable for pigging when installed correctly. HPS recommends PTFE gaskets, as they are more resistant to protruding into the internal bore.
Other connection types may also be considered depending on the application, location and required hygienic standard
Weld Quality and Pipeline Installation
Clean, well-aligned welds with minimal intrusion into the internal bore provide a smooth route for the pig and support reliable system performance.
The pipeline should also be properly supported to help prevent movement as the pig travels through the line.
HPS recommends anti-vibration cushion sleeve clamps instead of metal-on-metal clamps. These provide secure support while helping to protect the pipework from progressive damage.
As part of the system assessment, HPS will review the weld quality and pipeline supports, helping ensure the line is ready for safe and reliable pigging.
What Services Are Required?
The pig must be propelled through the pipeline using a suitable propulsion medium. Depending on the application, this may include:
- Filtered compressed air
- Nitrogen
- Carbon dioxide
- Water
- The product itself
The selected medium will depend on the product, process, hygiene requirements and site standards.
If air or gas is used to propel the pig, suitable services must be available and have sufficient capacity for the system. The requirements will depend on the pipeline, product, propellant and overall system design.
The precise requirements should be determined as part of the pigging system design rather than estimated from pipeline volume alone.
Is the Product Suitable for Pigging?
“If You Can Pump It, We Can Pig It!”
From low-viscosity beverages to thicker products such as chocolate, pastes, gels, paints and personal care products, most pumpable liquids and wet products are suitable for pigging.
Each application is individually assessed so the pig, system configuration and propulsion medium can be matched to the product and process.
The assessment will consider factors such as:
- Product type and viscosity
- Operating and cleaning temperatures
- Product compatibility
- Whether contact with air needs to be avoided
- Whether the product is susceptible to aeration or foaming
- Required hygiene standards
- Current transfer and cleaning processes
HPS pigging systems are used with a wide range of products, including food and beverages, chocolate, personal care and household products, chemicals, paints, coatings, lubricants, pastes and gels.
Information Needed to Assess an Existing Pipeline
Providing accurate process information at the beginning of a project helps determine whether the line is suitable and what modifications may be required.
Useful information includes:
- Pipeline internal diameter and approximate length
- Pipe material and standard
- Product or products being transferred
- Operating and cleaning temperatures
- Number and type of bends
- Existing valves and fittings
- Product sources and destinations
- Available propulsion services
- Current transfer, changeover and cleaning processes
- P&IDs, drawings or photographs of the line
It is also helpful to explain what the project needs to achieve, such as increasing product recovery, reducing waste, shortening changeovers or improving product routing.
Can Pigging Be Retrofitted to an Existing Process Line?
Yes. Pigging systems can often be retrofitted to existing process pipelines, as well as incorporated into new production lines.
HPS will assess the existing layout and determine the most effective way to introduce pigging. Many lines require only targeted changes to components such as valves, fittings, welds or selected sections of pipework.
Find out more about how HPS pigging systems integrate into existing pipelines.
The assessment establishes a clear pigging route and suitable system configuration, helping maximise product recovery while keeping changes and disruption to production to a minimum.
Is Your Pipeline Suitable for Pigging?
A pipeline does not need to be new or originally designed for pigging. Many existing process lines can be successfully adapted, often with only targeted modifications.
Send HPS your pipeline information, drawings or photographs and our system design team can carry out an initial assessment. We’ll identify the most suitable pigging route and explain any changes needed to help you increase product recovery, reduce waste and improve production efficiency.
Request a Pigging System Assessment
Find Out More
HPS assesses every application individually and can recommend any changes needed to make an existing process line piggable.
If you have any questions about liquid pipeline pigging for hygienic applications, or would like to improve product recovery and reduce waste, please get in touch.