Steel structures are a primary material in modern industrial and civil construction projects due to their superior durability and load-bearing capacity. However, when constructed and used outdoors, steel is highly susceptible to environmental factors. This article will provide a detailed analysis of the reasons for protecting steel structures, the types of anti-corrosion coatings, standard surface treatment procedures, and important considerations for routine maintenance of steel structures.
1. Why do steel structures need protection?
Rusting is an inevitable result of the oxidation process that causes metal corrosion when steel is frequently exposed to moisture, air, and harsh weather conditions. Particularly in coastal areas or heavy industrial environments containing many chemicals (acids, salts, alkalis), the rate of corrosion is very rapid and complex.
The initial manifestation of this phenomenon is the appearance of brittle brown or reddish-brown scales on the steel surface. Without protection or timely maintenance, the rust will continue to penetrate deeper, making the steel structure brittle, porous, and easily degraded. This severely reduces the strength, stiffness, and load-bearing cross-section of the component, directly threatening the safety and stability of the entire structure. Therefore, applying anti-corrosion measures from the fabrication stage is not only a technical requirement but also a vital factor in maintaining the project's lifespan.
2. Types of protective coatings: Powder coating and fire-resistant coating.
To protect outdoor steel structures, surface coating technology is the most common and optimal solution. Depending on the specific requirements of the project, powder coating and fire-resistant coating are two options that offer outstanding advantages.
Powder coating: Powder coating is a surface coating method using dry powder paint, operating on the principle of electromagnetism. The powder paint is positively charged via a spray gun, while the metal object is grounded and negatively charged. The electrostatic attraction helps the powder particles adhere tightly and distribute extremely evenly across the material surface. The component is then placed in a high-temperature oven to melt the paint, forming a strong, bonded film. The advantages of powder coating include a coating with good hardness, high scratch resistance, rust resistance, chemical corrosion resistance, and excellent color retention even in harsh outdoor weather conditions.
Intumescent paint: Steel itself doesn't burn, but it loses its strength when temperatures rise during a fire. Inflationary fire-retardant paint is a solution to protect steel structures from extreme temperatures. When exposed to high heat, this paint chemically reacts and expands 20 to 100 times its original thickness, forming a thick, porous layer of carbon foam. This foam acts as an insulating layer, preventing heat from rapidly spreading into the steel core, helping to maintain structural integrity for a certain period (60, 90, or 120 minutes), creating the "golden time" for evacuation and firefighting.
3. Standard steel surface treatment process
The protective coating will become meaningless and quickly peel off if the steel surface is not properly cleaned. Surface treatment of the metal according to ISO 8501-1 standards is a crucial first step, determining 80% of the lifespan of the protective coating.
In modern steel structure construction, abrasive blasting or sandblasting methods are widely used to achieve high-grade surface finishes. Sat. 2.5 (almost metallic white) or Sat. 3.0 (completely metallic white).
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In the Sa 2.5 standard, the pressure from the abrasive particles will thoroughly remove rust, mill scale, old paint, and other impurities. The steel surface after treatment must be absolutely clean, and only minor imperfections such as dots or streaks covering no more than 5% of the surface area are permitted.
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The abrasive blasting process not only cleans but also creates an ideal roughness profile, ranging from 50-100 micrometers. This roughness acts as millions of physical "anchors," allowing the primer to penetrate, creating a strong mechanical bond with the metal substrate, and preventing moisture and oxygen from entering.
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Immediately after cleaning, the steel surface must be blown clean of dust with compressed air and primed as soon as possible to prevent flash rust from returning due to environmental humidity.
4. Notes on periodic maintenance of steel structures
Regular maintenance of steel structures is not only for repairing damage but also a quality management strategy aimed at optimizing long-term costs. The maintenance process needs to adhere to reputable technical standards such as ISO 13822:2010 (Assessment of Existing Structures) and TCVN 12249:2018 (Guidelines for Maintenance of Steel Structures).
Key maintenance tasks include:
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Visual survey of the current situation: Conduct regular inspections to assess the degree of corrosion, degradation, or peeling of the paint layer. Pay particular attention to checking joints, welds, and bolt connections, as these are the areas most prone to water accumulation and rust formation.
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Assessing structural deformation: Measure and inspect the misalignment, deflection, or twisting of structural elements (columns, beams, braces). In continuously operating workshops, crane loads, machinery vibrations, and lateral winds can deform the frame system over time.
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Cleaning the roof drainage system: Gutters and roofing sheets should be regularly inspected and cleaned to prevent the accumulation of debris and leaves, which can cause rainwater to seep inside or cause waterlogging that leads to structural rust.
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Timely intervention and correction: When small rust spots or minor weld cracks are detected, immediate touch-up painting and reinforcement will prevent the spread of rust. Timely intervention significantly saves costs compared to replacing components or reinforcing the entire steel frame due to severe damage.
Establishing a precise surface treatment process, using advanced coating systems, and combining it with regular maintenance are the perfect trio of solutions to ensure outdoor steel structures remain sturdy, safe, and have a long lifespan of up to decades.
HAI LONG STEEL STRUCTURES IS A REPUTABLE MANUFACTURER OF STEEL BUILDING STRUCTURES.
Choosing the right steel structure processing partner is the decisive factor for the success of each construction project. In the context of the market increasingly demanding high quality, progress and safety, Hai Long Steel Structure Proud to be the leading brand trusted by many large domestic and foreign investors:
- Team experienced engineers, architects and experts, knowledgeable about the design and construction of warehouse factories according to international standards.
- Diverse construction capacity, meeting all project sizes and requirements, from simple to complex factories.
- We own a steel structure factory with a system of modern machinery and equipment that is among the best in the region. Ensuring fast, accurate, and safe construction.
- Professional construction process, is strictly managed.
You are looking for one Prestigious and professional steel structure manufacturing and erection unit? Please contact Hai Long Construction for free consultation and quote:
- HAI LONG CONSTRUCTION JOINT STOCK COMPANY
- Address: Taiyo Building, 97 Bach Dang, Hong Bang Ward, Hai Phong City, Vietnam.
- Hotline: 084 6625 888
- Email: info@hailongjsc.vn
