Cathodic Protection of a 57 km long pipeline section requires a few milliAmps of CP current. A new motorway bridge is built above the pipeline causing a potential risk of shielding the low cathodic current.

During the last decades, low alloyed steels with improved resistance to Sulfide Stress Cracking (SSC) have been developed for covering specific applications as heavy wall casings¹ or expandable tubings² or for reaching higher mechanical properties, such as 125 ksi Specified Minimum Yield Strength (SMYS) materials.^3-6 For the latter, relevant sour environments for developed grades are mild, meaning that all sour applications cannot be covered while a strong interest exists for O&G operators to use high strength materials when designing wells. Consequently, there is an incentive to push the limits of use of high strength sour service steels by enhancing their resistance to SSC. Several recommendations were already published when designing high strength sour service grades: hardness level shall be limited as much as possible and be preferentially below 22 HRC⁷, microstructure shall present a minimum required amount of martensite8 which is well known to be ideal for combining high mechanical properties and high resistance to hydrogen. Besides, many authors highlighted some other influencing parameters related to the material or the process.

Aging pipeline assets are a concern for many pipeline operators. As pipelines age, external corrosion control becomes more challenging and often results in more aggressive monitoring and maintenance activities such as more frequent in-line inspections (ILI) and direct examinations. A pipeline case study is discussed demonstrating how a digital twin based on mechanistic modeling was utilized as a proof of concept for identifying possible cathodic protection remedial actions to decrease external corrosion growth rates (CGR) with the goal of extending the ILI inspection interval from 3 to 5 years. Various remediations such as adjusting or adding cathodic protection and resolving interference are modeled and compared with the existing corrosion control configuration. An economic analysis is included to determine if theoretical remediations can reduce monitoring and maintenance costs while maintaining asset integrity.

Despite rapid development of electricity generation from wind compared to other renewable power sources in recent years, much greater efforts are still required to achieve the current level of sustained capacity growth to get on track with the Net Zero Emissions (NZE) by 2050 Scenario. One of the main challenges remains around the sustainability and cost reduction efforts for the offshore wind sector, especially related to operation and maintenance (O&M) costs. Monopiles, the most common foundation type in offshore wind farms, just like any other submerged metal structures are susceptible to corrosion, the maintenance of which could be very costly.

Corrosion prevention of the inside of a monopile structure has been challenging until today.

Although computational methods have been separately developed to predict corrosion and fatigue crack growth rates for metallic structures, challenges remain in implementing a methodology that considers the combined effects. In this work the output from a galvanic model is used to determine the spatial distribution of corrosion damage; providing a guide for the location of discrete corrosion damage features that can be analyzed using stress fields from structural models. In order to build confidence in this approach the galvanic models are validated by comparing predicted results to surface damage measurements from test specimens subject to ambient atmospheric exposure. There was good comparison between the predicted spatial distribution of corrosion damage and the measured surface damage profiles obtained from the galvanic test specimens. Following this exercise novel computational corrosion damage features were developed to represent simplified cracks shapes emanating from corrosion pits. Stress intensity factors (SIF) for these newly developed hybrid pit-crack features were determined and these solutions compared to cases where the pit is assumed to be an equivalent crack.  The impact of the local, cavity induced stress field, on the SIF solutions is discussed. Building on these findings a fatigue crack growth simulation was performed using an initial flaw emanating from a hemispherical cavity (corrosion pit) located at the edge of hole in a plate. A reasonable comparison, of the predicted number of crack growth cycles, to available experimental test results was achieved.