Why is Pig Speed Important?
Pigging speed is crucial to a safe and effective natural gas pipeline cleaning pigging program. A cleaning pig must obtain a seal within the line for the separation of dissimilar fluids in products pipelines, for condensate removal in gas pipelines, for commissioning and for providing secondary barriers for pipeline isolation. Pigs are designed for optimal cleaning at around 8 m/s. Slower speeds could result in a pig being held up at a weld, potentially resulting in a dangerous situation when the pressure builds behind the pig, and abruptly dislodges the pig, thrusting it away at speeds over 60 mph. Higher speeds will result in the pig bypassing debris and liquids, proving ineffective.
Product Flow Reduction Concerns
In large natural gas pipelines with ultra high velocities, operators are reluctant to reduce flows down for pigging, as this results in a reduction of revenue generating delivery. This poses a unique challenge in terms of effective cleaning for corrosion mitigation purposes or pre ILI runs.
Maintaining Optimal Cleaning Speed is Now Possible
To meet this challenge, Inline Services has designed a new series of Speed Control Pigs, specifically for these circumstances, which can maintain optimal cleaning speeds of 6 to 10 mph within a gas flow velocity of up to 33 mph. The Speed Control Pigs’ IMU constantly monitors and records its surrounding environment, which can be exported and analysed onsite. At predetermined speeds increased bypass is allowed through the pig to slow its progress and bypass is reduced to increase speed. The extra bypass through can be useful for moving loose deposits ahead of the pig. In addition, Inline’s Speed Control Pig can aid in the use of chemical inhibitors, determining quantities dispersed, recovery and liquids balance within the line.
Frequently Asked Questions
Why Is Pig Speed Important in Natural Gas Pipeline Cleaning?
Pigging speed is crucial to a safe and effective cleaning program. A pig must hold a seal to separate fluids, remove condensate, support commissioning, and act as a secondary isolation barrier. Pigs are designed for optimal cleaning at around 8 m/s.
What Happens When a Pig Runs Too Slow or Too Fast in a Line?
Slow speeds can leave a pig held up at a weld. Pressure then builds behind it and abruptly dislodges it, thrusting it away at over 60 mph, which is dangerous. Higher speeds make the pig bypass debris and liquids, so cleaning is ineffective.
Why Do Operators Avoid Reducing Flow for Gas Pipeline Pigging?
In large natural gas pipelines with ultra high velocities, cutting flow for pigging reduces revenue generating delivery. This makes effective cleaning for corrosion mitigation or pre-ILI runs a unique challenge.
How Do Speed Control Pigs Keep Optimal Cleaning Speed?
Inline Services Speed Control Pigs hold cleaning speeds of 6 to 10 mph in gas flow of up to 33 mph. At set speeds, bypass through the pig increases to slow it, and decreases to speed it up. Extra bypass also moves loose deposits ahead of the pig.
What Data Does the Speed Control Pig IMU Record and Provide?
The IMU constantly monitors and records the pig’s surrounding environment, and the data can be exported and analyzed onsite. The Speed Control Pig can also help with chemical inhibitor use, including quantities dispersed, recovery, and liquids balance in the line.
We Can Help Improve Your Natural Gas Pipeline Integrity Program
For more information about a recent project utilizing our Speed Control Pig, or to discuss how Inline Services can improve your Natural Gas Pipeline Integrity Program contact us at 281.401.8142 or toll free at 888.973.0079.
