There are several ways to validate the performance of a cathodic protection (CP) system for buried pipelines. Over the years, pipeline networks and their corrosion challenges have become increasingly complicated, not least due to the many sources of both AC and DC interference that affects CP operation. Also, the various measurement techniques that can be applied to test CP effectiveness has increased over the years. Finally, the sheer number of buried pipeline miles has been constantly increasing.
This paper will identify and document how these different factors affect the susceptibility of austenitic stainless steel to Chloride-Stress Corrosion cracking based on a review of currently available literature. A review of current industry best practices and a review of how the Oxygen content, the pH and application of stress relief affects Chloride-Stress Corrosion Cracking will be documented and presented.
Shown on Figure 1 is a typical impressed current CP diagram. When the rectifier is first turned on, i.e. time t=0, there is no polarization yet. At that moment, the applied DC voltage is fully consumed by IR drops at anode (IRa0) and cathode (IRc0), plus original potential difference between anode and pipe (Eoca- Eocc). When t=0, the current is at the greatest value. Over time when polarization kicks in, due to adding polarization resistance, the current is gradually reduced.
A recent review provided an overview of current microbiologically influenced corrosion (MIC) research. It established that despite extensive study and numerous publications, fundamental questions relating to MIC remain unanswered and stress the lack of information associated with MIC recognition, prediction, and mitigation (Little et al., 2020). On the other hand, bibliometric analysis on the MIC of engineering systems conducted a knowledge gap analysis to focus research efforts and to develop a roadmap for MIC research (Hashemi et al., 2018).
Oil and gas buried pipelines are protected against corrosion by both organic coatings, a passive protection system, and cathodic protection, an active protection system. When coating defects occur, CP controls the corrosion of the exposed steel surface. From an operating point of view, cathodic protection interruptions can occur on the network during interventions, consignments, or technical problems. Literature indicates that during CP interruption the corrosion rate of the metal remains lower than its free corrosion rate. Application of CP confers a remanence of protection to the metal. The objective of this study is to determine the safe duration for cathodic protection interruptions depending on environmental and cathodic protection conditions.
Precipitation hardened (PH) nickel alloys have been broadly used in various applications in the oil and gas industry thanks to its high strengths and outstanding corrosion resistance in several aggressive environments. Alloy 718 (UNS1 N07718), Alloy 925 (UNS N09925), Alloy K-500 (UNS N05500), Alloy 725 (UNS N07725), and others are among the most used PH nickel alloys in the oil and gas industry. Despite of their known high corrosion properties, hydrogen embrittlement is one common failure reported by the industry for this class of alloys.
From stress corrosion cracking of baffle-former bolts to radiological hazards from Co-60, corrosion of structural materials is the root of many operational issues that occur in light water nuclear reactors. Corrosion must be controlled to mitigate the risks of larger problems that reduce the operational time and lifespan of a reactor. One fundamental feature of nuclear reactors is the radiation field which is known to impact corrosion behavior. However, there is a severe lack of understanding the underlying mechanisms of radiation effects on corrosion, especially for stainless steels. Ion irradiation experiments allow for the controlled study of radiation effects on corrosion and to compensate for the lack of reactor data on structural materials.
The extension of nuclear reactor lifetimes beyond 40 years requires the qualification of plant components to ensure performance past their initial design requirements. Nickel-based alloys containing chromium (NiCr) are of concern at these extended lifetimes, as these types of alloys form an embrittling precipitate phase. Below a critical temperature—which is above the normal 300-400⁰C reactor operating temperatures—NiCr alloys form a stable, fully coherent MoPt2-typelong-range ordered (LRO) phase with stoichiometry Ni2Cr.
The Fukushima Daiichi Accident in 2011, which was the result of the Great East Japan Earthquake, tsunami, and prolonged station blackout, increased the focus on developing accident tolerant fuel cladding (ATFC), especially on the use of protective coatings. Coatings have been widely used in a variety of industries, including automotive, aerospace, and nuclear to improve corrosion resistance, enhance hardness and physical properties, and reduce wear. In an accident scenario, a coating may aid in reducing the oxidation kinetics and hydrogen evolution rates. The present study investigates the benefits that physical vapour deposited nitride-based coatings may have for ATFC.
The formation of carbon deposits and fouling of tubes is one of the most common operational issues regarding the operability and lifetime of materials at an industrial scale. Several billion dollars are spent worldwide on annual basis to upgrade/change materials apart from revenue loss on account of production halt and additional costs incurred in maintenances. Particularly, the carbon deposition in the refining process is an evitable and undesired factor. Most refineries worldwide have vacuum distillation, delayed cokers, visbreakers, or thermal cracking units where coke formation occurs faster due to high temperatures used in the process.
Geothermal energy is an excellent source of renewable clean power generation, as well as for heating and cooling. Unlike other renewable energy sources, it is unaffected by local climate conditions. However, the heat exchangers used in geothermal power plants are under constant threat of scale formation and corrosion due to the harsh operational conditions to which they are exposed. Therefore, surface modifications to heat exchanger materials, for example through coatings, are necessary to improving the efficiency and durability of geothermal plant.v
The Brazilian cost of corrosion was estimated at 3% of the GPD in 2018, that percentage is equivalent to approximately $US 49 billion, according to an ABRACO(1) journal released in 2020.1 It is estimated that from this cost $US 19 billion could have been saved through anticorrosive actions. In another research conducted by the EPRI(2) the results showed that at least 22% of corrosion costs could be avoided through adequate mitigating actions.2