Pigging & Drying

Pigging and drying are essential steps in the pipeline pre-commissioning process, ensuring that new or refurbished pipelines are free of debris, moisture, and contaminants before they are placed into service. These processes protect the integrity of the system, reduce long-term maintenance costs, and ensure compliance with industry and safety standards.

At American Pipeline Solutions (APS), we provide reliable pigging and drying services that prepare your pipelines for safe, efficient operation.

Pigging: Preparing the Pipeline for Service

The first step in pre-commissioning is pipeline pigging, which involves running specialized devices (known as pigs) through the line to remove construction debris, mud, scale, and standing water.

APS utilizes a variety of cleaning pigs equipped with transmitters, allowing our team to monitor their progress and ensure complete coverage throughout the line. These pigs are carefully selected based on pipeline size, material, and the type of debris present. Common pig types include:

• Foam pigs for removing residual water and soft debris

• Brush pigs for scraping scale and tougher deposits

• Bi-directional pigs for cleaning pipelines where flow may be reversed

• Tracking pigs for accurate location monitoring

This step is critical to prevent future flow restrictions and to prepare the system for effective drying.

Pipeline Drying: Achieving the Correct Dew Point

Once pigging and de-watering are complete, pipeline drying begins. APS deploys a sequence of soft foam swabs and drying pigs until no residual water remains. The line is then dried using advanced methods such as:

• Oil-free compressors – ensuring clean, moisture-free air flow

• Desiccant dryers – removing trace humidity to achieve precise dew points

• Nitrogen drying – introducing an inert atmosphere to displace moisture and protect against oxidation

The industry standard for natural gas and many other systems is a -40° dew point. Achieving this target ensures that no excess moisture will be introduced into the product flow, helping to prevent corrosion, hydrate formation, and downstream equipment damage.

Why Pigging and Drying Matter?

Skipping or rushing these steps can result in serious operational challenges. Common risks include:

• Corrosion and scale buildup from residual moisture

• Blockages caused by leftover construction debris

• Hydrate formation in natural gas systems

• Flow inefficiencies that reduce throughput and increase energy costs

Proper pigging and drying not only extend pipeline life but also help operators avoid costly repairs, downtime, and compliance issues.

APS’s Expertise in Pigging & Drying

With years of experience in pipeline pre-commissioning services, APS has the equipment and technical knowledge to handle projects of varying size and complexity. Our crews are trained to work with:

• Large-diameter pipelines requiring extended pigging runs

• Complex systems with multiple low points and moisture traps

• A variety of materials, including steel, ductile iron, HDPE, and PVC (with surface preparation when needed)

By combining transmitter-equipped pigs, reliable drying equipment, and proven procedures, APS ensures your pipeline is cleaned and dried to exact specifications—ready for safe and efficient operation.

Contact APS for Pigging & Drying Services

If you’re preparing a pipeline for commissioning, trust American Pipeline Solutions to deliver complete pigging and drying services that meet industry standards. Contact our team today to discuss your project requirements and ensure your pipeline is ready for service.

FAQs:

What is pigging in pipeline pre-commissioning?

Pigging is the process of running specialized devices, called pigs, through a pipeline to remove construction debris, mud, scale, and standing water before the line goes into service. In pre-commissioning, pigging sets the foundation for drying and inspection by clearing the internal bore. APS selects pig types based on pipeline size, material, and the nature of the debris present.

Why do pipelines need drying after pigging and de-watering?

Even after pigging and de-watering, small amounts of moisture can remain on the pipe wall or in low points. Pipeline drying removes this residual water to reach a specified dew point, often -40°. This level of dryness helps prevent internal corrosion, hydrate formation in gas systems, and damage to downstream equipment once the line is in operation.

What dew point is typically required for a dried pipeline?

For natural gas and many similar systems, a -40° dew point is commonly specified. This target indicates that the pipeline will not contribute significant additional moisture to the product flowing through it. APS designs drying procedures to meet the required dew point and documents the results as part of pre-commissioning closeout.

What types of pigs does APS use for cleaning and drying?

APS uses a range of cleaning pigs equipped with transmitters so their progress can be monitored along the line. Foam pigs are used for removing residual water and soft debris, brush pigs help scrape scale and tougher deposits, and bi-directional pigs are used where flow may be reversed. Soft foam swabs and drying pigs are then deployed to remove remaining moisture before final drying.

How does APS dry pipelines after pigging and de-watering?

Once pigging and de-watering are complete, APS sends additional cleaning pigs and soft foam swabs through the line until visible water and scale are removed. The line is then dried using oil-free compressors, desiccant dryers, or nitrogen, depending on project requirements. These methods work together to achieve the specified dew point and a stable, dry internal environment.

What happens if pigging and drying are skipped or rushed?

Skipping or rushing pigging and drying can leave debris and moisture inside the pipeline. Over time, this can lead to corrosion, scale buildup, hydrate formation in gas systems, and blockages that restrict flow. Operators may face reduced throughput, increased energy costs, unplanned downtime, and potential compliance or safety issues.

Which types of pipelines can APS support with pigging and drying?

APS works on a wide range of pipeline systems used for gas, liquids, and industrial applications. Our teams handle large-diameter cross-country lines as well as complex facility piping with multiple low points and moisture traps. We adapt our pigging and drying procedures to each system’s layout, operating conditions, and material.

What pipeline materials can be cleaned and dried by APS?

APS has experience working with steel, ductile iron, HDPE, and PVC pipelines, adjusting techniques and surface preparation as needed. The choice of pigs, swabs, and drying methods is matched to the material to achieve effective cleaning and drying without unnecessary risk. Our goal is to meet specifications while protecting the asset’s internal surfaces.

Why are transmitters used on cleaning pigs?

Transmitters embedded in pigs allow APS crews to track the pig’s position as it moves through the line. This ensures complete coverage, helps identify potential slow zones or obstructions, and confirms that each pass reaches the intended receiver. Accurate tracking supports both operational control and project documentation.

How do pigging and drying support long-term pipeline integrity?

By removing debris and moisture before a pipeline enters service, pigging and drying reduce the conditions that promote internal corrosion and blockages. This improves flow efficiency, supports accurate future inspections, and extends the overall service life of the asset. For operators, it means fewer unplanned interventions and more predictable maintenance planning.