Pipeline Pigging Guide
What Is Pipeline Pigging?The Complete Australian Guide
Quick Answer
Pipeline pigging is the practice of inserting a device called a 'pig' into a pipeline and propelling it through the line — using the existing product flow or an external medium — to clean, inspect, dewater, dry, or batch the pipeline. The process does not stop normal pipeline operations.
Published by Royal Poly Products
Jandakot, Western Australia
Contents
1. What is a pipeline pig?
2. Why is it called a pig?
3. What does pipeline pigging do?
4. Types of pipeline pigs
5. Foam pig density explained
6. How does the pigging process work?
7. When should you pig a pipeline?
8. Pipeline pigging in Australia
9. Frequently asked questions
1. What Is a Pipeline Pig?
A pipeline pig is a maintenance tool — typically cylindrical or bullet-shaped — that is inserted into a pipeline and travels along its interior length, driven by the flow of gas, water, oil, or another propulsion medium. As it travels, the pig performs work on the interior of the pipeline: scrubbing debris, removing liquid, separating products, or recording inspection data.
Pipeline pigs are manufactured from a variety of materials depending on their intended purpose. Foam pigs are made from open-cell polyurethane foam, often coated with polyurethane elastomer for added durability. Mechanical pigs use a steel mandrel body fitted with polyurethane cups, discs, or wire brushes. Solid cast pigs are fully moulded from polyurethane. The design, density, and coating of the pig are chosen to match the pipeline’s diameter, product type, debris load, and operating pressure.
Australian Manufacturing
Royal Poly Products designs and manufactures its full range of pipeline pigs in Jandakot, Western Australia — meaning shorter lead times, local technical support, and products engineered for Australian pipeline conditions.
2. Why Is It Called a Pig?
The name ‘pig’ has been used in the pipeline industry since the early days of pipeline transport.
Pipeline folklore holds that the first cleaning devices — made from leather strapping or straw bales bound with wire — made a loud squealing noise as they traversed the pipeline under pressure, not unlike the sound of a pig. The name stuck, and today it is the universal industry term worldwide.
The devices are also sometimes called ‘scrapers’, ‘go-devils’, or ‘swabs’ depending on their type and the region of the world. In Australia, ‘pig’ and ‘pipeline pig’ are the standard terms used by operators, contractors, and manufacturers.
3. What Does Pipeline Pigging Do?
Pipeline pigging is used across a wide range of pipeline operations. The specific function
depends on the type of pig used and the operational objective. The most common uses are:
Cleaning
Removing debris, scale, wax, silt, biofilm, sediment, and other contaminants from the interior bore of a pipeline. Regular cleaning pigs maintain flow efficiency and prevent build-up that would restrict product delivery or cause corrosion.
Dewatering
After hydrostatic pressure testing — which is mandatory for most new pipeline installations in Australia — the pipeline must be fully dewatered before it can be commissioned for gas or product flow. Foam pigs are the preferred choice for dewatering operations, often run in sequence to progressively remove water until the pipeline is dry.
Drying
Following dewatering, a drying pig (typically a low-density foam pig) is run to remove residual moisture. This is critical for gas pipelines and any pipeline where water contamination would compromise product quality or cause internal corrosion.
Batching and Product Separation
In multi-product pipelines, pigs are used to physically separate different products as they are pumped sequentially through the same line. This prevents contamination and mixing at product changeover points.
Gauging
A gauging pig carries a metal plate (gauge plate) with a diameter slightly smaller than the pipe bore. As the pig travels through the pipeline, any deformation, obstruction, or weld intrusion bends the plate. Inspecting the plate after retrieval reveals the internal condition and any restrictions within the line.
Inline Inspection
Intelligent pigs — also called smart pigs or inspection pigs — are fitted with electronic sensors (magnetic flux leakage, ultrasonic, caliper) that measure and record the internal condition of the pipeline wall as they travel. The data is downloaded after the pig is retrieved and analysed to identify corrosion, metal loss, cracks, dents, and other integrity issues.
Pipeline Integrity Programs
Many pipeline operators run scheduled pigging programs as part of their overall pipeline integrity management plan — combining cleaning pigs with periodic inspection runs to maintain safe, efficient, and compliant pipeline operations over the long term.
4. Types of Pipeline Pigs
Pipeline pigs fall into two broad categories: utility pigs (used for cleaning, dewatering, batching, and gauging) and inspection pigs (used for inline inspection and integrity data collection). Within these categories, there are many specific types:
| Pig Type | Primary Use | Best For | Density / Style |
|---|---|---|---|
| Foam Pig | Cleaning, drying, dewatering, batching | New pipeline commissioning, light debris removal | Low / Medium / High density |
| Disc Pig (Bi-directional) | Sealing, liquid removal, product separation | Pipelines without dedicated launcher/receiver | Mandrel body with polyurethane discs |
| Cup Pig | Heavy debris removal, cleaning | Gas and water pipelines, long runs | Mandrel body with cup seals |
| Solid Cast Pig | Batching, product separation, dewatering | Multi-product pipelines, post-hydrotest | Fully cast polyurethane |
| Dual Diameter Pig | Complex pipeline systems | Pipelines with varying bore diameters | Custom foam or disc configuration |
| Gel Pig | Chemical cleaning, corrosion inhibition | Difficult-to-clean pipelines, pre-commissioning | Viscous gel formulation |
Royal Poly Products manufactures all of the utility pig types listed above — foam pigs, disc pigs, cup pigs, solid cast pigs, and dual diameter pigs — from its facility in Jandakot, Western Australia. The company also supplies pipeline gels as standalone cleaning agents or in conjunction with foam pig runs.
5. Foam Pig Density Explained
Foam pigs are the most widely used pig type in Australian pipeline operations. They are made from open-cell polyurethane foam and are available in four standard densities, each suited to different operational requirements:
| Density | Spec (kg/m³) | Typical Application | Pipeline Type |
|---|---|---|---|
| Low density | 16–32 kg/m³ | Line proving, drying, light liquid removal | New pipelines, gas lines |
| Intermediate density | 40–56 kg/m³ | Light cleaning, batching, dewatering | Water mains, product lines |
| Medium density | 80–96 kg/m³ | General cleaning, debris removal | Oil, gas, water pipelines |
| High density | 128–160 kg/m³ | Heavy debris, scale, wax removal | High-pressure oil & gas lines |
Royal Poly Tip
Selecting the wrong foam density is the most common cause of poor pigging results. Too light and the pig won't generate enough differential pressure to clean effectively. Too heavy and you risk the pig getting stuck, particularly in older pipelines with reduced bore sections. Always consult with a pigging specialist before selecting pig type and density for a new or complex pipeline.
6. How Does the Pigging Process Work?
The pigging process follows a well-established sequence used on pipelines across Australia and internationally:
1. Pig selection —
The pig type, size, density, and coating are chosen based on the pipeline's internal diameter, operating conditions, product type, and pigging objective.
2. Pig insertion —
The pig is loaded into a pig launcher — an oversized barrel section of the pipeline fitted with an isolation valve and closure. On smaller pipelines (2–6"), a pig can be inserted directly into a valve or tee.
3. Launching —
The launcher is closed and pressurised. The differential pressure behind the pig propels it into the pipeline and along the bore. The pig travels at a speed proportional to the pipeline flow rate — typically 0.5 to 5 m/s.
4. Tracking —
Pig signalers — either intrusive (contact-based) or non-intrusive (magnetic detection) — are positioned at key points along the pipeline to confirm the pig has passed. Royal Poly Products supplies pig signalers to complement its pig range.
5. Receiving —
At the far end of the pipeline, the pig is captured in a pig receiver — a similar oversized barrel section. The receiver is isolated, depressurised, and the pig is safely removed.
6. Post-run assessment —
The pig is inspected for wear, debris, and damage. The volume of material removed is assessed. If the pigging objective has not been met, additional pig runs may be required with progressively more aggressive pig types.
One of the major advantages of pipeline pigging is that the pipeline can continue operating normally throughout the entire pigging process. Product flow does not need to stop — the pig simply travels with the product.
7. When Should You Pig a Pipeline?
There are several key scenarios that call for pipeline pigging:
New pipeline commissioning
Before a new pipeline is placed into service, it must be gauged (to confirm bore dimensions and the absence of obstructions), flooded for hydrotesting, dewatered, and dried. Foam pigs are the primary tool for commissioning pigging sequences.
Routine maintenance cleaning
Operational pipelines accumulate internal deposits over time — wax, scale, silt, biofilm, corrosion products. A scheduled cleaning program using foam or mechanical pigs maintains flow efficiency and reduces corrosion risk. For natural gas pipelines, pigging frequency is typically every 2–10 years depending on conditions. For water and product pipelines, more frequent programs may be required.
Before inline inspection
Before a smart pig run, the pipeline must be clean enough for the inspection tools to travel and function accurately. A series of cleaning pigs is typically run first to prepare the bore.
After shutdown or extended lay-up
Pipelines that have been shut down, flooded, or left idle may accumulate significant debris and may require dewatering and cleaning before returning to service.
Problem response
A sudden drop in flow rate, an increase in operating pressure, or an anomaly identified in a previous inspection may trigger an unscheduled pigging run to identify and address the cause.
8. Pipeline Pigging in Australia
Australia has an extensive network of onshore pipelines transporting natural gas, crude oil, refined products, and water across all states and territories. The majority of Australia's long- distance gas transmission pipelines run through Western Australia, Queensland, New South Wales, and South Australia — connecting production fields, processing plants, and distribution networks.
Pipeline pigging is carried out on these networks by pipeline operators, contractors, and specialist service providers throughout the year. Australian pipeline operators are required to comply with AS 2885 (Pipelines — Gas and Liquid Petroleum) for the design, construction,
operation, and maintenance of high-pressure pipelines, which includes integrity management requirements that drive regular pigging programs.
Water utilities — including Water Corporation WA, SA Water, Sydney Water, and Melbourne Water — also run extensive pigging programs on water transmission and distribution mains to maintain flow capacity and water quality.
Locally Manufactured
Royal Poly Products is based in Jandakot, Western Australia — just minutes from the Port of Fremantle. This strategic location allows the company to supply pipeline pigs rapidly to WA- based projects and operators, and to export to clients in Southeast Asia and the Middle East. All products are manufactured in Australia under ISO 9001:2015 quality certification.
9. Frequently Asked Questions
What does a pipeline pig look like?
Most foam pigs look like a bullet or cylinder — rounded at the front, slightly compressed at the sides to create a seal against the pipe wall, and flat or concave at the rear to generate drive pressure. They can range in size from a few centimetres in diameter for small-bore pipes, to over a metre in diameter for large transmission lines. Mechanical pigs look more like a short cylindrical device with discs, cups, or brushes attached to a central steel mandrel.
Can a pipeline pig get stuck?
Yes — a stuck pig is one of the most serious operational issues in pipeline pigging. It typically occurs if the pig is oversized for the bore, if there is an unexpected restriction in the pipeline (such as an unpiggable valve, a weld bead, or a severe bend), or if the pig disintegrates during the run and a piece lodges in the line. Royal Poly Products can design and supply retrieval pigs and bypass pigs to assist in recovering a stuck pig.
Do you need to stop pipeline operations during pigging?
No — one of the key advantages of pipeline pigging is that the pipeline can continue operating during a pig run. The pig simply travels with the product flow. The launcher and receiver are fitted with isolation valves that allow safe loading and retrieval without interrupting operations.
What is the difference between a foam pig and a mechanical pig?
A foam pig is made from polyurethane foam — flexible, lightweight, and able to negotiate tight bends, tees, and diameter changes. A mechanical pig (also called a mandrel pig) uses a rigid steel central body with polyurethane cups or discs and optionally wire brushes. Mechanical pigs provide a better seal and more aggressive cleaning action but require a fully piggable pipeline (correct bend radii, full-bore valves, consistent diameter).
How do I choose the right pig for my pipeline?
The key factors in pig selection are: pipeline internal diameter, product type (gas, water, oil), operating pressure, pipeline geometry (bend radii, valves, diameter changes), the type and volume of debris to be removed, and the distance of the run. Royal Poly Products provides technical consultation to help operators select the correct pig for their application — contact the team via https://royalpolyproducts.com/get-a-quote/.
Are pipeline pigs reusable?
Foam pigs are generally single-use — they are inspected after a run and, if significantly worn or
contaminated, discarded. Mechanical pigs (disc pigs, cup pigs) have replaceable wear components (cups, discs, brushes) and can be refurbished and reused multiple times, making
them cost-effective for long-term pigging programs.
What is a pig signaler?
A pig signaler (also called a pig indicator or pig detector) is a device mounted on the outside of the pipeline that detects when a pig passes a specific point. Non-intrusive signalers detect the pig magnetically or by acoustic means, without penetrating the pipe wall. Intrusive signalers use
a spring-loaded flag or switch that the pig physically trips as it passes. Royal Poly Products supplies both types.
What regulations apply to pipeline pigging in Australia?
In Australia, high-pressure gas and liquid petroleum pipelines are regulated under AS 2885 (Pipelines — Gas and Liquid Petroleum). Operators are required to implement Pipeline Integrity Management Plans (PIMPs) that include scheduled inspection and cleaning programs. State- based pipeline safety regulators (such as the Energy Safety Regulator in WA and the AER nationally) oversee compliance.
Need a Pipeline Pig for Your Australian Project?
Royal Poly Products designs and manufactures foam pigs, disc pigs, cup pigs, solid cast pigs, dual diameter pigs and pipeline gels right here in Western Australia. Fast turnaround, ISO 9001 certified, Australian made.
About Royal Poly Products
Royal Poly Products is an Australian manufacturer of pipeline pigs and pigging solutions, based in Jandakot, Western Australia. The company designs and manufactures a full range of foam pigs (low, intermediate, medium, and high density), bi-directional disc pigs, cup pigs, solid cast pigs, dual diameter pipeline pigs, and pipeline gels, supporting pipeline operators across Australia and internationally.
ISO 9001:2015 certified and a recipient of the Western Australian Export Award (Emerging Exporter 2025) and the Australian Export Award, Royal Poly Products combines local manufacturing expertise with global quality standards to deliver reliable pigging products for gas, water, oil, and industrial pipeline applications.
Website: royalpolyproducts.com
Phone: +61 08 6117 9204
Address: Unit 5/41 Biscayne Way, Jandakot WA 6164, Australia
Email: sales@royalmechgroup.com