ABSTRACT
This paper presents new applications of Volatile Corrosion Inhibitors (VCI) inside new and/or existing out-of-service pipelines. The system utilizes a combination of soluble and volatile corrosion inhibitors that are directly applied into the pipeline. In some cases, the decrease in the corrosiveness of environment is done by increasing the pH. Different approaches are discussed depending on pipeline design and operating considerations of the owner. A recurring issue during the construction and commissioning, and sometimes operation, of facility pipe (pump station and terminal) assets is the creation of internal corrosion threats due to leftover hydrotest water or product. Available methods for removing the water or product entirely, or applying inhibitor chemicals to the hydrotest medium or product, are time-consuming and expensive. In 2015, 2016, and 2017 VCI chemicals were applied to various facility piping systems in lieu of other methods which would mitigate internal corrosion threats. This method, while not a best-practice in the oil and gas industry at the time, was shown through laboratory testing to be effective at mitigating both biological and generalized internal corrosion. The application of VCI was also proven to be safe for the personnel involved, which was one of the original objections of the operator, and the application process resulted in significant cost savings at the time of commissioning. This paper details a single preservation project as an example.
INTRODUCTION
Internal corrosion in metal pipelines is one of the greatest time-dependent threats affecting newly constructed, deactivated, or idled assets. New construction presents additional variables, such as leftover uninhibited hydrotest water, that increase the risks associated with internal corrosion. In mainline pipe that can be cleaned, inhibited, and inspected with inline tools and devices launched from traps, there are a multitude of ways to mitigate the risks presented by internal corrosion. However, with facility pipe, internal corrosion threats - especially from leftover hydrotest water where the pipe was not internally lined - are compounded by configurations that make owners unable to clean, inhibit, or inspect with inline tools (in most cases). In the case of buried facility pipe, external direct inspection is not possible to prevent leaks or ruptures, the consequence of which could be worsened by an inability for local staff to inspect visually, and the lack of leak detection equipment that would otherwise be present for a mainline system and thoroughfare facility pipe.
