The Challenge of Corrosion in Industrial Settings
The oil and gas sector, like most industries that depend on significant infrastructure, is engaged in a never-ending battle against time. Tanks, pipelines and other metallic assets are under constant threat of decay due to corrosion. Exposure to oxygen and other elements cause chemical reactions that gradually eat away at the metal, which results in equipment that no longer works as well as intended. With enough time, these assets will fail entirely, no longer capable of storing or transporting materials.
Corrosion is influenced by numerous environmental and operating conditions. Moisture and oxygen are common contributors, while carbon dioxide (CO₂), hydrogen sulfide (H₂S), chlorides, salts, temperature, pH, and other conditions can affect corrosion mechanisms and rates. Internal corrosion also may be influenced by the composition of the fluid moving through a pipeline, as well as flow velocity and the presence of water or contaminants.
Because these variables differ among facilities and applications, corrosion prevention requires an understanding of both the asset and its operating environment. Identifying the mechanisms contributing to corrosion helps organizations determine which combination of materials, protective systems, chemical treatments, monitoring methods, and maintenance practices may be appropriate.
This is why companies in the energy, transportation and maritime industries in particular are always looking for ways to prevent corrosion so they can protect their equipment and get the most productivity out of it. Read on to learn more about some of the most popular methods for preventing corrosion and the role chemical dosing systems can play.
What Are Corrosion Prevention Chemicals?
Corrosion prevention chemicals are substances used to help reduce or control the chemical and electrochemical reactions that contribute to the deterioration of metals. Depending on the application, these chemicals may alter the corrosive environment, interact with a metal surface, reduce the presence of a corrosive constituent, or form a protective film that limits contact between the metal and the surrounding environment.
Chemical treatment can be particularly useful for internal corrosion in pipelines and process equipment where applying a conventional external coating is not practical. However, the appropriate treatment depends on the system. Metallurgy, process chemistry, temperature, pressure, pH, flow conditions, and the presence of corrosive substances all can influence chemical selection and application.
Corrosion inhibitors are one important category of corrosion prevention chemicals. Different inhibitors use different mechanisms, making chemical selection, dosage, and delivery important parts of an effective treatment program.
Common Types of Corrosion Inhibitors
Corrosion inhibitors can be categorized according to how they interact with the metal or process environment. Some commonly used categories include:
Film-forming inhibitors — These chemicals adsorb onto or interact with metal surfaces to form a protective film. The film reduces contact between the metal and corrosive components in the process stream. Film-forming inhibitors are commonly considered for internal corrosion control in pipelines and process equipment.
Anodic and cathodic inhibitors — Corrosion is an electrochemical process involving anodic and cathodic reactions. Certain inhibitors interfere with one or both of these reactions, reducing the overall corrosion rate under appropriate conditions.
Oxygen scavengers — Dissolved oxygen can contribute to corrosion in many water-containing systems. Oxygen scavengers react with dissolved oxygen, helping reduce its availability to participate in corrosion reactions.
pH-control chemicals — The acidity or alkalinity of a process environment can influence corrosion behavior. Chemical treatment may be used in applicable systems to adjust pH and create conditions that are less conducive to particular corrosion mechanisms.
These categories are not interchangeable. The type of inhibitor and treatment strategy should reflect the metallurgy, process fluid, corrosion mechanism, and operating conditions of the specific system.
Key Methods of Corrosion Prevention
There are several ways to prevent corrosion in metal infrastructure, each of which has its own unique set of pros and cons:
Barrier Coatings — Applying paint, powder coating or plastic film to metal surfaces limits their exposure to moisture and other environmental factors that can lead to corrosion. Of all the anti-corrosion methods, this may be the simplest to achieve, as the coatings are applied directly to the assets. However, these are not invulnerable and will flake or chip over time. Regular maintenance is required, which can be daunting for large-scale facilities.
Hot-Dip Galvanization — Steel can be dipped into molten zinc to create a corrosion-resistant alloy. This is because the iron reacts with the zinc to create a specialized coating that protects the underlying metal from the outside environment. Although this method is highly effective and has been used for centuries, it cannot be done on-site. This means it is not practical for equipment that has to remain in service.
Stainless Steel — Another type of alloy that helps resist corrosion is stainless steel, which is created by combining steel with other metals such as nickel and chromium. This helps strengthen the metal and give it greater resistance, but the process is so expensive that alloying large amounts of steel needed for infrastructure is not cost-effective.
Cathodic Protection — This method involves inserting sacrificial anodes into the pipeline, which work to give their own electrons to the metal so as to prevent corrosion. In essence, these anodes corrode in place of the actual asset, keeping it from corroding. Although this method is effective, it does involve the periodic replacement of the anodes to ensure the process continues. These anodes also add to the overall weight of the assets, which can be a problem in many applications.
Combining Corrosion Prevention Methods
Corrosion management does not necessarily rely on a single method. Depending on the asset and corrosion mechanisms involved, organizations may use multiple strategies together. Material selection and protective coatings, for example, may be combined with cathodic protection, chemical treatment, inspection, and corrosion monitoring.
This layered approach recognizes that assets can encounter multiple corrosion threats throughout their service lives. External surfaces may require protection from soil, moisture, or atmospheric exposure, while internal surfaces may be exposed to water, gases, chemicals, and contaminants carried by the process stream. A corrosion management program can account for these different risks and provide methods for evaluating how conditions change over time.
Factors to Consider When Selecting Corrosion Prevention Chemicals
Chemical selection should be based on the conditions within the system rather than assuming that one inhibitor or treatment approach is suitable for every application. Several factors may influence treatment decisions.
Metallurgy is an important consideration because different metals and alloys respond differently to corrosive environments and chemical treatments. Process-fluid composition also matters. The presence of water, oxygen, carbon dioxide, hydrogen sulfide, salts, or other constituents can influence both the corrosion mechanism and the type of chemical treatment considered.
Operating conditions should also be evaluated. Temperature and pressure can affect chemical behavior, while flow rate and velocity can influence chemical distribution and the ability of a protective film to remain on a metal surface. The pH of the process environment may further affect corrosion behavior and inhibitor performance.
Operators also need to consider chemical compatibility, dosage requirements, injection locations, and interactions with other chemicals used within the process. Evaluating these variables helps establish a treatment program appropriate for the equipment and its operating environment.
Using Chemical Injection Skids for Corrosion Prevention
One of the most effective and popular methods of protecting infrastructure from corrosion is the use of chemical inhibitors. These are injected into the pipeline through the use of chemical injection skids, which are installed at strategic points throughout the system to inject them into the line with precise control.
Corrosion inhibitors can operate through several mechanisms. Depending on the chemistry and application, an inhibitor may adsorb onto the metal surface to establish a protective film, affect anodic or cathodic reactions, reduce the concentration of a corrosive constituent, or modify process conditions. The treatment method should correspond to the corrosion mechanism identified within the system.
Chemical injection skids provide the equipment necessary to store, meter, and deliver treatment chemicals into a process at controlled rates. A system may incorporate chemical storage, metering pumps, valves, piping, instrumentation, controls, and injection equipment according to application requirements.
How Chemical Injection Supports Corrosion Control
Effective chemical treatment involves more than selecting an inhibitor. The chemical also needs to reach the appropriate location at a dosage suitable for the process conditions. Insufficient treatment may limit corrosion protection, while inappropriate chemical use can increase operating costs or create other process concerns.
A properly configured chemical injection system provides greater control over how treatment chemicals enter the process. Injection rates can be established according to system requirements, and operating data can be used to evaluate whether changes are necessary as conditions evolve.
Injection location is another important consideration. The system needs to introduce the chemical where it can effectively interact with the process stream and reach surfaces requiring treatment. Flow, pressure, chemical properties, equipment configuration, and process conditions can all influence injection-system design.
Together, chemical selection and controlled delivery provide a more systematic approach to chemical corrosion treatment.
Why Corrosion Monitoring Matters
Introducing a corrosion prevention chemical does not mark the end of a corrosion management program. Organizations also need a way to evaluate conditions and determine whether treatment is performing as intended. Corrosion monitoring provides information that can help operators understand corrosion behavior and identify changes over time.
Different monitoring technologies can be used according to the application. Corrosion coupons can provide information about material loss over a defined exposure period. Electrical resistance probes can measure changes associated with metal loss, while linear polarization resistance equipment can support corrosion-rate measurements in suitable conductive environments.
Monitoring data can help organizations evaluate corrosion trends, assess treatment performance, and determine whether changing process conditions warrant further investigation. When combined with inspection information and operating data, these measurements can contribute to decisions involving inhibitor dosage, maintenance planning, and broader asset integrity activities.
The relationship between chemical treatment and monitoring is particularly important because process conditions are not always static. A program that performs appropriately under one set of operating conditions may need to be reviewed when fluid composition, temperature, flow, or other variables change.
Build a Comprehensive Corrosion Management Strategy
Corrosion control requires an understanding of the asset, its environment, and the mechanisms that contribute to material degradation. Protective coatings, material selection, cathodic protection, corrosion prevention chemicals, chemical injection, inspection, and monitoring can each play a role within a broader corrosion management strategy.
Combining prevention with ongoing monitoring allows organizations to move beyond simply applying a treatment. They can collect information about corrosion behavior, evaluate performance, and adjust their approach as operating conditions change.
SMARTCORR® offers a wide range of chemical injection skids that provide exceptional performance in protecting equipment from corrosion and other applications. Our experts can help you find the unit that is best suited for your particular industry and needs, so reach out to us today.
Fighting corrosion is a perpetual struggle, but one that is absolutely necessary for many industries. Choosing the right mitigation strategy means being aware of your industry’s requirements and the specific environmental conditions you face. Talk to one of our representatives today to learn more about how a chemical injection skid may be the solution you need.