How Environmental Factors Influence Pipe and Metal Corrosion Rates in Coastal Structures

The U.S. is home to a total coastline of 12,383 miles and around 88,633 miles of shoreline. That is a massive territory where businesses in everything from shipping to energy development are trying to streamline operations.

While having a beach view and access to necessary operational resources is crucial to maintaining a business, the coast can be one of the most challenging environments for your infrastructure. Ensuring the longevity of your pipe and metal structures requires careful consideration of salt, moisture, temperature fluctuations, biological activity, and more.

Without engineers on your side who can implement cathodic protection design and other prevention strategies to mitigate the risk of coastal operation, you will run into expensive repairs and downtime. It helps to understand the mechanisms behind corrosion in any coastal setting before deciding to protect a bridge build, install more pipelines, or clear an offshore platform for production.

Understanding Corrosion in Coastal Environments

The odds are that if you operate any business, industrial, or commercial enterprise on the coast, you already know what corrosion is firsthand. This is the chemical or electrochemical reaction between metal and the surrounding environment. The longer the corrosion is in place, the more you risk material degradation.

When considering the coastal areas of the world, corrosion is likely to accelerate. Usually, this is because of the high salt concentration, but persistent moisture exposure to any body of water will do.

Corrosion can and will compromise the structural integrity of any pipe and metal components you have around your property. The result is increased leaks, collapses, and structural failure.

Types of Corrosion Affecting Coastal Infrastructure

Corrosion happens to a wide range of metals. Hiring cathodic protection consultants helps you select the best-fit metals for your various needs. However, not all corrosion is the same. Some of the more common include:

• Uniform Corrosion: When your metal experiences an even (often widespread) loss of material across its surface due to prolonged exposure.
• Galvanic Corrosion: Whenever two different metals come in contact with a conductive solution (like seawater), it accelerates the material loss.
• Pitting Corrosion: Typically a focused attack where you find small holes in a segment of metal, usually triggered by a change in chloride ions due to seawater exposure.
• Crevice Corrosion: Any stagnant water trapped in a tight space will promote aggressive chemical reactions.
• Stress Corrosion Cracking (SCC): When tensile stress in your structure combines with a corrosive environment and wreaks havoc on your materials.

With so many varied methods of corrosion happening, many businesses turn to experienced and professional cathodic protection design to reduce the chances of metal oxidation by redirecting electrical currents away from any potentially vulnerable infrastructure.

Common Environmental Factors Influencing Corrosion Rates

Before we run through a quick list of common environmental factors that will impact corrosion rates, be sure you know there is no one quick answer to what is happening at your location. It takes a bit of research and an experienced eye to uncover the underlying causes of your issues. That being said, here is the list:

01 | Salt & Chloride Exposure

Salt in seawater and airborne particles around coastal properties will 100% increase the rate of corrosion. These geographic regions have more chloride ions that penetrate protective metal coatings. Over time, that disrupts the passive oxide layers, preventing oxidation and directly leading to deep pitting and weakness of your structures.

02 | Humidity & Moisture

You don’t have to be enjoying a location next to the Florida coastline to experience corrosion. Anywhere there are higher humidity levels, you’ll end up with a constant layer of moisture on your metal surfaces. Unlike drier places, you never get the chance to completely dry off your structure, meaning they are constantly exposed to corrosive elements.

03 | Temperature Fluctuations

Coastal climates love extreme temperature shifts. Afternoon rainstorms, higher winds, and seasonal shifts exacerbate corrosion in pipe and metal components. That will lead to thermal expansion and contraction, inducing more stress points that weaken your structures when exposed to prolonged environmental factors.

04 | Oxygen Availability

This corrosive warning is a bit unique. Putting your operations into an oxygen-rich environment will accelerate metal oxidation. Think of submerged or partially submerged structures. The aeration around these structures causes corrosion to concentrate in specific areas. That is why you find more issues at waterline sections.

05 | pH Levels & Soil Composition

Soil conditions vary on the coastline. Corrosion rates shift due to varying levels of acidity, alkalinity, and contamination in the ground. Some specialized cathodic protection design is essential to extending the usable life of your metal structures.

06 | Biological Activity & Microbiologically Influenced Corrosion (MIC)

Microorganisms love the coast as much as aging retirees. Microorganisms (like sulfate-reducing bacteria) thrive in any oxygen-deprived space. They generate hydrogen sulfide, which reacts with metal and leads to material loss.

07 | Wind & Weather Patterns

You don’t have to be right on the water for corrosion. High winds will send salt spray and abrasive particles to pipe and metal structures even a few miles away. Over time, those winds, hurricanes, and tropical storms increase the likelihood of corrosion.

Think about all the infrastructure near coastlines. Bridges made of metal with support beams, offshore oil platforms, coastal pipelines, and even the jet ski rental company with a metal dock system will be exposed to a greater impact of corrosion. Without cathodic protection design or similar preventative measures, the business is put at greater risk.

Strategies to Mitigate Corrosion in Coastal Structures

As there are many different reasons for increased corrosion, there are also a number of preventative methods to mitigate corrosion risk. Most businesses will start with protective coatings and marine-grade paint. These include epoxies, polyurethanes, and zinc-rich primers that help defend against oxidation.

Not all structures can use protective layers due to heat or chemical presence. In those cases, cathodic protection systems are far more efficient. The two primary methods are:

• Sacrificial Anode Protection: Using zinc or aluminum anodes and attaching them to structures so they corrode instead of the underlying metal.
• Impressed Current Cathodic Protection (ICCP): Sending an electrical current through the metal to counteract electrochemical reactions that cause corrosion.

Modern components are leaning heavily into corrosion-resistant alloys like stainless steel or composite materials, but those are still not suitable for some niche markets like energy, oil, and industrial applications.

The best solution is to implement a cathodic protection design and then schedule proactive maintenance and inspections that limit direct exposure due to environmental controls.

Conclusion

While the coast presents a harsher setting for infrastructure, exposed pipe and metal components can be protected against aggressive environmental factors, so corrosion is not as serious an issue. Careful consideration of salt levels, humidity, temperature, and biological activity must be addressed so structure failures are limited.

At Dreiym Engineering, we offer decades of experience implementing such designs. Our corrosion protection services are led by the National Association of Corrosion Engineers (NACE)-certified CP4 professionals. When you work with our cathodic protection consultants, you can rest assured you are in the trusted hands of qualified and experienced team members.

Contact our engineers today, and let’s schedule a consultation for any of your corrosion needs, including cathodic protection along the coast.