New Pig Designs for Corrosion Pit Cleaning and Multi-Diameter Capability

PPIM 2017 Presentation: Performance of a Low-Drag Seal Assembly for Pipeline Pigging and a Novel Corrosion Pit Cleaning Brush

Pipeline corrosion mitigation is critically important to ensure the safe and responsible operation of the world’s pipeline infrastructure. Pipeline maintenance and cleaning pigs are typically utilized in an overall corrosion mitigation program which can include: utility pigging stages for debris and wax removal, scouring and cleaning of the interior pipe walls and batching chemical application, and intelligent pigging stages for the inline identification, inspection and monitoring of internal corrosion.

Cleaning internal corrosion pitting presents a specific challenge in pipeline corrosion mitigation. Localized corrosion pitting in pipelines can create localized environments supporting Under-Deposit Corrosion (UDC) and the ideal environment for Microbially Induced Corrosion (MIC). Small diameter pits deep into the pipeline wall represent the most challenging scenario due to the difficulty of reaching deep into the small pits and removing sludge and deposits. If allowed to progress without effective cleaning, these small corrosion pits can lead to ‘pinhole’ pipeline leaks that are difficult to detect with standard SCADA and flow assurance methods but can lead to significant environmental incidents.

The Pipeline Integrity and Corrosion Monitoring (PICOM) team at Alberta Innovates Technology Futures (AITF) has developed and previously presented a standardized testing methodology and flow loop to quantify the effectiveness of pigging for cleaning corrosion pits. These detailed studies identified that significant improvements are required to more effectively address cleaning corrosion pits to improve the mitigation of under deposit corrosion.

Fiberbuilt Manufacturing has developed a new pipeline pig system to address and improve the cleaning of these pipeline corrosion pit features. This newly developed pigging system was tested to quantitatively determine the improved corrosion pit cleaning performance. The new Fiberbuilt pigging system was also tested in multiple pigging run scenarios to determine and define the optimum strategy for corrosion pit cleaning as a part of the overall mitigation pigging program. The original testing and qualification program was extended from previous studies and the full results will be presented here.

In addition to the advances in corrosion pit cleaning, this novel pigging system utilizes a next generation seal design, providing an effective pigging seal with only a very low differential pressure required. The Fiberbuilt seal platform creates a customizable drag (operating differential pressure) for pipeline pigs that can virtually eliminate pig surging. When used in an in-line inspection application, the new Fiberbuilt pigging seals provide an extremely stable pigging speed profile that improves overall inspection performance and accuracy. Detailed results including demonstrations of the customization of operating back pressure will be presented.

The next generation Fiberbuilt pigging seal will also improve pigging operations in upstream gathering systems that may have very little available drive pressure. A very low drag (differential pressure) pigging

system will allow upstream gathering lines to be pigged effectively at a higher frequency without restricting well productivity of the wells tied in ‘upstream’ in the gathering system. The Fiberbuilt pigging seals coupled with the new corrosion pit cleaning system will both improve the performance of corrosion mitigation pigging and allow these pressure sensitive gathering systems to be economically pigged at a higher frequency than was possible before.

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