Royal Poly Products — Engineered for Australian Pipeline ConditionsEngineered for Australian Pipeline Conditions

What types of deposits do pipeline cleaning pigs remove?

Pipeline cleaning pigs are designed to address a wide range of internal contaminants depending on the pig configuration selected. Common deposits include: paraffin wax and waxy crude build-up in oil pipelines; mineral scale and calcium carbonate deposits in water pipelines; iron oxide and corrosion scale in gas and water pipelines; biofilm and microbial deposits; construction debris including weld slag, mill scale, and sand from new pipelines; and general particulate sediment that settles in low-flow sections. The nature of the deposit determines which pig configuration — from a light bare foam pig to an aggressive silicon carbide or wire brush pig — is appropriate.

How do I choose between a foam pig and a disc pig for cleaning?

Foam pigs are generally preferred for cleaning applications that require geometric flexibility — particularly in pipelines with multiple bends, diameter changes, or check valves. Foam pigs also absorb residual moisture as they travel, which can be beneficial in combination cleaning and dewatering applications. Disc pigs deliver a more rigid, consistent seal against the pipe bore and can carry brush attachments that provide more focused scraping action on the pipe wall. For heavy scale removal or weld bead cleaning where targeted abrasion is needed, a disc pig with brush rings may be more effective than a foam pig. In practice, many cleaning programs use both — foam pigs for initial sweeping and condition assessment, followed by disc brush pigs for more intensive cleaning where deposits have been identified.

What foam pig density should I use for cleaning?

Foam pig density determines how aggressively the pig contacts the pipe wall and how much drive force it requires. The selection depends on the nature of the deposit and the condition of the pipeline: Low density pigs are used for light sweeping, product batching, and initial passes in pipelines with uncertain bore conditions. Intermediate density pigs suit moderate cleaning duties and are a good starting point for lines with no recent cleaning history. Medium density pigs are the most commonly used for routine operational cleaning — they deliver reliable wall contact without risking damage to internal coatings. High density pigs deliver maximum cleaning force and are reserved for heavily contaminated lines or where previous lighter passes have confirmed the bore can handle a more aggressive pig.

Can cleaning pigs damage an internal pipe coating?

Yes — an incorrectly specified or overly aggressive cleaning pig can damage internal coatings, particularly where the coating has aged, softened, or is already showing signs of delamination. This is why pig selection must account for the coating type and condition, not just the nature of the deposits to be removed. Wire brush pigs and silicon carbide pigs should not be used on coated pipelines without careful assessment of the coating specification and condition. For coated pipelines, bare foam pigs or nylon brush pigs are generally safer choices that can achieve good cleaning results without abrading the coating surface. If in doubt, start with a lighter configuration and assess the results before increasing aggressiveness.

How many cleaning runs are needed before a pipeline is ready for inline inspection?

The number of pre-inspection cleaning runs depends on the condition of the pipeline and the sensitivity of the inspection tool to debris. As a general guide, the inspection tool vendor will specify a cleanliness standard the pipeline must meet — typically expressed in terms of maximum debris volume or deposit type — before the tool is deployed. For a pipeline with a regular cleaning history, two to three progressively more aggressive foam pig passes may be sufficient. For a pipeline with no recent cleaning history or known heavy deposits, a more extensive program involving four to six or more runs — including wire brush or silicon carbide passes — may be required. The pig receiver debris at each run provides a practical guide: when successive runs produce negligible debris, the bore is approaching a clean baseline.

What is a pre-commissioning cleaning sequence for a new pipeline?

A typical pre-commissioning cleaning sequence for a new pipeline involves: an initial low-density foam pig pass to remove loose construction debris; one or more intermediate density pig passes to dislodge bonded scale and weld residues; a medium or high density pass if significant deposits remain; a a href=”https://royalpolyproducts.com/products/bi-directional-pigs/disc-gauging-pigs/” class=”fw-600″>gauging pig run to confirm bore clearance; and then transition to the dewatering and drying program if applicable. The number and configuration of cleaning passes is specified in the project’s pre-commissioning procedure, which should be developed in advance by the commissioning contractor in consultation with the pipeline owner and pig supplier.

How do I know if the cleaning program is working?

The most direct evidence of cleaning progress is the debris recovered at the pig receiver after each run. At the start of a cleaning program on a dirty pipeline, large volumes of wax, scale, sand, or corrosion products may be collected. With successive runs, the debris volume should decrease — indicating that the cleaning program is progressively removing deposits from the bore. When two or more successive runs produce little or no debris, the pipeline has reached a baseline clean condition. Changes in debris character — for example, a shift from soft wax to hard scale — can indicate that the initial deposits have been removed and harder bonded material is now being addressed, which may call for a change in pig configuration.

Can pigs be used for chemical cleaning applications?

Yes. In some cleaning programs, chemical cleaning agents — corrosion inhibitors, biocides, scale dissolvers, or wax dispersants — are injected as slugs ahead of or between pig passes to enhance the cleaning effect. The pig then sweeps the chemical slug along the pipeline bore, maintaining contact time with the deposits. This approach is particularly useful for stubborn wax or scale deposits that mechanical pig action alone cannot fully remove. Pipeline gel slugs between pig passes can also serve as a carrier medium for chemical agents. Compatibility between the pig material, the chemical agent, and the pipe wall coating should be confirmed before any chemical cleaning program is executed.

Do you supply wire brush pigs in stainless steel for offshore applications?

Yes. Royal Poly Products supplies wire brush foam pig and disc pigs with stainless steel brush elements for offshore and corrosive-environment applications where carbon steel brush pigs would be susceptible to rust contamination. Stainless steel brush pigs are also used in pipelines carrying products sensitive to iron contamination, such as certain process chemicals or treated potable water. Nylon brush pigs — non-sparking and non-metallic — are available for hazardous area applications or pipelines where metallic debris must be avoided entirely.

What is the minimum order quantity for cleaning pigs?

Royal Poly Products does not impose minimum order quantities on standard cleaning pig products. We supply single pigs for specific project applications as well as bulk orders for operational pigging programs. For non-standard sizes or custom configurations, lead times and minimum quantities may apply. Contact our sales team with your pig specifications and required quantities and we will provide a prompt quote