In pipeline operations, what is a 'pig' used for?

In pipeline operations, what is a 'pig' used for?

• A. A device sent through a pipeline to inject chemicals.
• B. A device to pressurize the pipeline for testing.
• C. A device sent through a pipeline to clean, inspect, or measure the pipe interior; a swab is used to remove liquids or separate gas pockets.
• D. A device used to meter flow rate at the outlet.

Answer: (C)

In pipeline work, a pig is a device sent through the pipeline to clean, inspect, or measure the pipe’s interior. The swab-type pig is used to remove liquids and push ahead liquids, which helps prevent liquid buildup and separate gas pockets that can cause flow issues. More advanced or “smart” pigs carry sensors to inspect the pipe wall for corrosion, dents, or other defects, supporting maintenance and integrity testing. This is why the description of cleaning, inspecting, or measuring inside the pipe best fits the purpose of a pig. Pigs aren’t used to inject chemicals, pressurize the line for testing, or meter flow at the outlet—that’s accomplished by other equipment or processes.

In pipeline work, a pig is a device sent through the pipeline to clean, inspect, or measure the pipe’s interior. The swab-type pig is used to remove liquids and push ahead liquids, which helps prevent liquid buildup and separate gas pockets that can cause flow issues. More advanced or “smart” pigs carry sensors to inspect the pipe wall for corrosion, dents, or other defects, supporting maintenance and integrity testing.

This is why the description of cleaning, inspecting, or measuring inside the pipe best fits the purpose of a pig. Pigs aren’t used to inject chemicals, pressurize the line for testing, or meter flow at the outlet—that’s accomplished by other equipment or processes.