Abstract
A critical step in ensuring that a pipeline is fit and healthy for operations is continuous scraping “cleaning” and frequent scraping inspection. If scraping activities are not properly performed, pipeline integrity can be at risk. Running effective cleaning scrapers through pipelines will remove accumulated solid debris and leftover liquids as well as smoothen the pipe wall. This will reduce pipeline pressure, increase product flow as well as maintaining product specs. Moreover, it is a pre-requisite step before conducting in-line inspection as the different technologies either magnetic flux or ultrasonic have minimum cleanliness specifications for the sensors to perform properly and achieve a successful inspection. In typical cases, few cleaning runs with proper design. In typical cases, one or two cleaning runs are sufficient before the In-Line Inspection (ILI) to meet the requirements. However, in other cases, the cleaning may become more challenging and require careful designing and planning of “progressive cleaning”. In this paper, a specific case study will be discussed where the pipeline has not been cleaned since construction due to its low velocity, which has been improved recently to meet the minimum operating parameters requirements for cleaning and ILI scraping activities, associated with a long distance of over 200 km. This led to the expected accumulation of debris left over from construction phase as well as the potential for additional debris from operations. At the beginning, operating parameters simulation was performed to ensure that the required parameters for the scraping activities was achieved. Consequently, the progressive cleaning starts with evaluation foam tool followed by non-aggressive cleaning (without brushes and magnets) then gradually to more aggressive with brushes and magnets. A gate-stage criteria was developed to move between the phases that included review of the scraper data during the run, condition of the received tool, amount of debris received and encountered operational challenges. The scraper tool design was selected based on rigorous review between the operator and the vendor to account for the expected challenged. For example, the tool was equipped with brush discs and high-resistance guide discs to compensate for the expected wear and use of a unidirectional design after confirming the safe passage of the entire pipelines by a Bi-Di cleaning scraper. Moreover, the tool was equipped with a tracking mechanism with enough signal strength considering the amount of debris, and maximum possible battery life considering run duration and anticipated challenges. The overall progressive cleaning plan, the different tool designs, and the results of each cleaning phase will be described in the paper.
