Fighting corrosion with chemical expertise

Pipeline corrosion is the most common of the many issues and challenges pipeline operators face – and may often be disastrous. Industries and communities are heavily reliant on the integrity and condition of pipeline assets. Corrosion is something that operators have to contend with, but too often, corrosion is left untreated, spiralling into a more consequential issue than necessary.

When ignored or handled poorly, the long-lasting damage of corrosion will compromise the integrity and lifespan of pipeline assets. This is especially true – and will be increasingly visible – as energy demands evolve and infrastructure changes. New pipelines continue to be developed and expanded upon in new regions, including high-consequence areas (HCAs) and in deeper reservoirs where temperatures and pressures increase. This places even greater significance on the integrity of assets in complex situations and environments. The result, when mismanaged, is expensive and poses a risk to assets, projects, the environment, local communities, and workforces. If a reactive (instead of proactive) approach is taken in corrosion management, it is likely to result in wasting significant resources, materials, and productive time.

The oil and gas industry has taken great strides in several aspects of pipeline inspection and integrity (such as updated pipeline technologies and infrastructure); however, the impact of corrosion remains. The Association for Materials Protection and Performance (AMPP) reported that the impact of corrosion costs upwards of US$1.372 billion annually. Corrosion in pipeline assets can be split into internal and external corrosion. The US Pipeline and Hazardous Materials Safety Administration (PHMSA) believes that internal corrosion is responsible for approximately 60% of all pipeline incidents caused by corrosion in transmission and gathering pipelines. To understand how to mitigate the serious risks of corrosion, it’s critical to recognise the causes of corrosion.

What causes corrosion?

Unfortunately for oil and gas operators, internal and external corrosion occurs naturally in pipelines exposed to the elements. In addition, several chemical components in the materials carried by pipelines may lead to corrosive reactions. These include oxygen, water, moisture, acid chloride, and common bacteria and microorganisms. One of the main types is sour corrosion. This is caused by hydrogen sulfide (H2S) that may occur in crude oil and natural gas. Sour corrosion degrades assets, creating rust within metal infrastructures such as steel-based pipelines. Naturally occurring corrosion may be exacerbated by a lack of proper maintenance and neglect. Whether natural or due to neglect, the result of corrosion is often the same: the loss of critical properties and structural strength, risking the pipelines breaking down or at worst, rupturing. Thankfully, several methods exist to combat and minimise the effects of corrosion.

How to mitigate the effects of corrosion

Corrosion in pipelines that transport H2S-containing materials is an area that operators have sought to address because of its relevance in the upstream and midstream markets. With sulfide naturally appearing in oil throughout its journey along a pipeline, operators must consider the causes and appropriate prevention strategies to avoid economic loss and operational risk.

Understanding the risks, including those that occur naturally and those that are avoidable, is crucial to maximising the asset’s performance and lifespan. Recognising the potential causes of degradation and corrosion will help identify the appropriate solutions when required further down the line. Through dedicated inspection and access to the latest technologies, solutions, and treatment chemicals, operators can manage a pipeline to ward off the effects of corrosion.

The development and implementation of proven corrosion management strategies will help secure asset longevity alongside other benefits, including optimising performance and full compliance with the latest regulatory standards for health, safety, and the environment, while helping to avoid costs for long-term maintenance issues. Comprehensive corrosion control measures, along with regular maintenance and inspection, will help reduce the impact of internal corrosion. Through dedicated and thorough maintenance, operators can significantly increase the pipeline lifespan.

Chemical treatment

Chemical treatment is a standard industry approach to minimise corrosion. These chemicals include corrosion inhibitors (that prevent corrosion) and biocides (that prevent microbially induced corrosion). Tetrakis (hydroxymethyl) phosphonium sulfate (THPS) is a commonly used biocide; a safe and effective liquid component that targets and controls the growth of harmful bacteria and microorganisms.

Introduced into the midstream market to support pipeline inspection and integrity, THPS has since been proven effective in targeting microbial growth and the specific bacteria that lead to hydrogen sulfide formation and souring.

Since its introduction to the industry, operators who use biocides such as THPS have experienced prolonged waiting times to receive results on its effectiveness. Monitoring the biocide’s progress is critical to understanding the necessary volume to inject into various pipeline sections. This lack of oversight has posed challenges as excessive biocide use can elevate corrosion risks and associated chemical expenses, while insufficient dosages may lead to microbial-induced corrosion (MIC), thereby diminishing the pipeline’s lifespan.

Alongside the solutions, it is critical to have assurance they are being utilised correctly. For the chemicals to effectively protect the system, they must reach all areas of the pipeline. To ensure this is happening at the required dosage requires timely and accurate testing of chemical residuals.

The effectiveness of various chemical choices is crucial, but they are not a one-size-fits-all solution; the chemicals used must match the specific conditions of the pipeline. And that is where expertise is essential.

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