How Should Electrical Enclosures Be Selected for Coastal Projects? — IP Rating Does Not Equal Corrosion Protection

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If you are an electrical engineer or procurement officer for an EPC project and are selecting electrical enclosures for a coastal or chemical project, this article will help you figure it out:

1. Why do IP67-rated enclosures still corrode in coastal environments?

2. What three dimensions should be considered when selecting corrosion protection products?

3. What is ISO 9223? Why is it increasingly mentioned in EPC tenders?

4. What are the three key questions you need to understand before selecting a product?

This article was written by the BSUMWELL technical team. We are a manufacturer and wholesaler specializing in waterproof electrical enclosures. Our products cover three major material series: stainless steel, aluminum, and PC/ABS plastic, with protection levels ranging from IP55 to IP68. We also support OEM/ODM customization.

1. The first misconception in selecting corrosion protection equipment: "IP67 = corrosion protection"

1.1 What does the IP rating test cover? — Pure water, physical protection, excluding salt spray.

When selecting equipment, many engineering procurement personnel see an outer shell labeled "IP67" and assume that "it's waterproof and dustproof enough, and should be fine for coastal projects."

This is a very common and very dangerous misunderstanding.

IP rating (IEC 60529 standard) tests two things: dustproof and waterproof.

• The "6" in IP67: Represents complete dust protection

• The "7" in IP67: It indicates protection against short-term immersion (1 meter deep, 30 minutes).

However, IP rating does not involve testing the material's corrosion resistance at all.

The test medium was pure water, not seawater, salt spray, or chemical solvents. An IP67 enclosure made of ordinary materials would still be corroded by salt spray in a coastal environment—no matter how good the seal is, if the material itself cannot withstand salt spray, the protection level is meaningless.

The "7" in IP67 represents the waterproof rating, not the corrosion resistance rating.

Our enclosure products offer protection ratings from IP67 to IP68, but we always remind our customers that IP rating does not equal corrosion resistance. When selecting a product, both the material and the protection rating must be considered.

1.2 What does the "X" in NEMA 4X stand for? — An industry reference for corrosion protection standards

(Note: NEMA standards are primarily used in the North American market. They are cited here as industry knowledge to help understand the logic behind determining corrosion resistance levels. Actual selection should be based on the applicable standards system in the project's location.) 

Since IP ratings do not include corrosion resistance testing, what industry standards are used to measure the corrosion resistance of casings?

NEMA (Electrical Manufacturers Association) standards are the most commonly used enclosure protection standards in the North American market. The difference between NEMA 4 and NEMA 4X perfectly illustrates the difference between "waterproof" and "corrosion-resistant".

• NEMA 4: Protected from wind, rain, and water spray from hoses (≈IP66), but does not include corrosion protection requirements.

• NEMA 4X: In addition to NEMA 4, there is an additional requirement for corrosion resistance – “X” stands for “Corrosion-Resistant”.

Differences in testing between NEMA 4X and IP ratings:

NEMA 4X requires the enclosure to pass the ASTM B117 salt spray test (5% NaCl solution, continuous atomized spray at 35°C, according to ASTM B117 standard), typically requiring 200-500 hours of no substrate corrosion (according to NEMA 250 standard, the specific duration varies depending on product type and testing institution). IP ratings, however, do not involve this testing at all.

Simply put: NEMA 4X = waterproof + corrosion resistant, IP67 = waterproof (but not corrosion resistant).

1.3 The correct logic for selecting materials for coastal projects—IP rating + anti-corrosion materials are both indispensable.

Coastal projects face two threats simultaneously: water and salt.

• IP rating solves the "water" problem—Prevent water from entering the interior of the tank during heavy rain, washing, or short-term immersion.

• Anti-corrosion materials solve the "salt" problem—Prevent salt spray from corroding the enclosure material, leading to rust, perforation, and structural failure.

It's not a matter of "choosing one over the other," but rather "neither can be dispensed with."

• Only IP67 rated, material not corrosion resistant.→ Salt spray corrodes the enclosure from the outside, causing it to rust through after a few years.

• Material corrosion resistant, insufficient IP rating→ Water entered the enclosure during heavy rain, causing a short circuit in the internal components.

Correct selection = matching IP rating + matching corrosion-resistant material.

Our full range of enclosures covers IP67 to IP68 protection ratings, and includes three main material series: stainless steel, aluminum, and PC/ABS plastic, allowing for flexible matching based on the corrosion level of the project. [View the full range of waterproof and corrosion-resistant shell products] 

Frequently Asked Questions (FAQ) Quick Answers [P0 - Add FAQ Block]

Q: Can an IP67 enclosure be used in a coastal environment?

A：It's usable, but only if the material is corrosion-resistant. IP67 addresses the issue of "whether water can get in," not "whether the material will be corroded by salt spray." An IP67-rated enclosure made of ordinary material will still rust after a few years in a coastal environment. The correct choice is: IP67 + corrosion-resistant material.

Q: What is the difference between NEMA 4X and IP67?

A：The key difference lies in the testing content. IP67 tests for dust and water resistance (immersion in pure water) but does not include any corrosion testing. NEMA 4X, in addition to weather resistance, requires passing the ASTM B117 salt spray test to verify the material's corrosion resistance. Simply put: IP67 is "waterproof," while NEMA 4X is "waterproof + corrosion resistant."

Q: Is stainless steel a must for coastal projects?

A：Not necessarily. It depends on the specific corrosion level and budget. For C5 (within 2 kilometers of the coastline), stainless steel or high-grade corrosion-resistant materials are recommended; for C3-C4 (nearshore areas), an aluminum shell with a marine-grade coating is also feasible; for C1-C2 (dry inland areas), PC/ABS plastic is sufficient. The key is a three-dimensional match of "material + protection level + usage environment".

2. The essence of corrosion protection selection – three-dimensional matching of “material + protection level + usage environment”

2.1 Three-Dimensional Selection Framework – Three Questions to Define the Selection Direction

Choosing the right corrosion protection solution isn't that complicated. Just ask yourself three questions in order, and the answer will come:

Step 1: Define the usage environment

Determine the corrosion level of the project:

• Dry inland (C1-C2) → Standard materials are sufficient

• Industrial Zone/Offshore (C3-C4) → Corrosion-resistant materials required

• Coastal/Oceanic (C5-CX) → High-grade anti-corrosion materials are required

(Unsure about the corrosion rating? Refer to ISO 9223 classification, see section 2.2 for details.)

Step 2: Determine the protection level

Determine based on the installation location:

• There may be a rain shelter indoors → IP54-IP65

• Outdoors, possibly directly hit by torrential rain → IP66

• Low-lying areas, prone to short-term flooding → IP67

• Underwater or continuous immersion → IP68

Step 3: Balance budget and weight

Quick comparison of the three materials:

With the answers to the three questions, the "material + protection level + usage environment" have a clear direction for implementation.

Our product line covers three major materials: stainless steel, aluminum, and PC/ABS plastic, with protection ratings ranging from IP67 to IP68. No matter the environment of your project, you can find a suitable enclosure solution. OEM/ODM customization is supported.

2.2 Introduction to ISO 9223 Corrosion Classes – Which class does a coastal project typically fall under?

ISO 9223 (based on ISO 9223:2012) is an internationally recognized standard for classifying atmospheric corrosivity. It categorizes atmospheric environments into six levels based on their corrosivity, from lowest to highest:

Coastal projects typically fall under the C5 or CX category:

• Within 2 kilometers of the coastline → C5

• Offshore wind power platforms and island projects → CX

• Chemical plants typically belong to C4 or C5 Grade (depending on the specific chemical medium).

More and more EPC tender documents are directly referencing ISO 9223—corrosion rating determines the required grade of materials and coatings. Suppliers who can proactively provide selection advice according to ISO 9223 have a significant advantage in bidding.

We can provide material selection recommendations based on the project's ISO 9223 corrosion rating. Higher corrosion ratings place stricter requirements on materials—choosing the right rating helps prevent premature failure.

2.3 A quick overview of the anti-corrosion characteristics of the three major materials—from C1 to CX, which one is right for you?

Brief description of material characteristics and applicable scenarios:

• PC/ABS plastic: Suitable for inland and general outdoor environments. Absolutely zero corrosion, but attention should be paid to the risk of UV aging and stress cracking under certain chemical media.

• Aluminum casing: Suitable for industrial areas and near-shore environments. It offers significant advantages in terms of lightweight design, but requires high-quality coating protection – coating damage can lead to electrochemical corrosion.

• Stainless steel: Suitable for highly corrosive environments such as coastal and offshore areas. It has the strongest corrosion resistance and can achieve more than 20 years of maintenance-free operation, but it has the highest initial cost and weight.

The specific anti-corrosion mechanisms, real-world examples, and selection details of the three materials will be discussed in detail in the next article of this series.

Our product line covers three major material series: stainless steel, aluminum, and PC/ABS plastic – whether your project is at the C1 or CX corrosion level, there is a corresponding material option.

3. Ask yourself 3 questions before selecting corrosion protection equipment.

3.1 Three Questions for Self-Check in Product Selection

Before you begin selecting a model, ask yourself these three questions:

Question 1: In what environment is the project located?

• [ ] How far is it from the coastline? (<2km or >2km)

• [ ] Are there any chemical gases present? (Chemical plant/farm/sewage treatment plant)

• [ ] Is there a risk of high humidity or condensation?

Question 2: Will the installation location get wet?

• [ ] Is it located in a low-lying area? (Flooding is possible after heavy rain)

• [ ] Is it in a coastal typhoon zone? (Possibly flooded by seawater)

• [ ] Is high-pressure water jet cleaning required? (Routine maintenance method)

Question 3: Budget and weight restrictions?

• [ ] Is the project budget sufficient?

• [ ] Is the load-bearing capacity of the mounting bracket limited?

• [ ] Are there any additional requirements for heat dissipation? (e.g., if there are heat-generating components such as frequency converters inside)

Based on the answers to these three questions, and referring to the selection framework in section 2.1, we can initially determine the material direction and protection level.

3.2 Next steps after self-inspection

After completing the three-question self-check, you may have a preliminary direction for your selection. If you are still unsure, please feel free to contact us.

For specific project-specific corrosion protection selection advice, please contact our technical team. We can provide free selection assessments based on ISO 9223 corrosion levels and project requirements, typically offering preliminary advice within 24 hours.

[Contact our technical team for a free selection assessment]

Summary of the key points of this article

1. IP rating does not equal corrosion resistance. —IP67 is a waterproof test and does not include salt spray or chemical corrosion tests.

2. The "X" in NEMA 4X represents its corrosion resistance.—Unlike NEMA 4, it must pass the ASTM B117 salt spray test.

3. Correct selection formula—Matching IP rating + matching anti-corrosion material.

4. Three-dimensional selection framework—Usage environment → Protection level → Material selection.

5. ISO 9223 is a key reference.—Coastal projects typically fall under the C5-CX category.

(Next article preview: With the selection framework finalized, we'll delve into a comparison of the corrosion resistance mechanisms and real-world performance of stainless steel, aluminum, and PC/ABS. Please read the second article in this series, "Stainless Steel, Aluminum, and PC/ABS—Real-world Performance and Applicable Scenarios of These Three Materials in Salt Spray Environments.")