We Super Steel Manufacturing Co.,Ltd(SMC) are amongst the top manufacturers and suppliers for the seamless steel pipe, welded steel pipe, OCTG products and fittings from China. We have been manufacturing and supplying these products to the industry since 1993, and received repeat orders and appreciation from our valued customers.
High quality piping products from approved manufacturers.
In order to continuously improve our offerings to our clients, we have consistently improved and upgraded our manufacturing facility and can hence offer material with stringent requirements.
Over the years, Super Steel Manufacturing Co.,Ltd(SMC) has developed an enviable reputation for project management for the Oil & Gas, Construction, Power Energy, Marine & Offshore, Water Treatment, Exploration & Drilling Services, Pipeline & Petrochemical and other heavy industries.
The many years of experience that we have means that there is always someone who has the ability to carry a project forward.
Always up to date. In this column you can find the steel pipe related articles, including industry trends, product standards and materials, and some technical guidelines.
Plastic-coated steel pipes combine the strength of steel with the corrosion resistance of plastic. The steel provides mechanical durability, while the plastic layer prevents corrosion, wear, and electric leakage. Among many types of pipelines, they are widely used in construction, municipal works, chemical industry, power, and mining due to this dual advantage.
A critical factor influencing their corrosion resistance is the thickness of the plastic coating. A thin coating provides only limited protection—prone to water and chemical penetration, especially in humid or aggressive environments. Once compromised, the underlying steel corrodes quickly. In contrast, a thicker coating acts as a stronger barrier, slowing down corrosive penetration and resisting mechanical damage, making it suitable for harsh conditions such as marine, chemical, and industrial environments.
However, thicker is not always better. Excess thickness increases cost and construction complexity. Thus, choosing the right thickness requires balancing performance, cost, and the specific application environment.
Super Steel Manufacturing Co.,Ltd is professional plastic-coated steel pipe manufacturer, for more details, please contact:sales@super-steels.com
Role of Coating Thickness in Corrosion Protection
When the coating is too thin, it fails to block corrosive agents effectively. Moisture can penetrate through tiny pores, leading to electrochemical corrosion. Thin coatings are also prone to mechanical damage, which exposes the steel surface to further corrosion.
In contrast, thicker coatings serve as a stronger barrier. They lengthen the path for corrosive substances to reach the steel and provide better resistance to impact and wear. This is especially important in harsh environments such as marine, underground, or chemical settings.
Comparison of Coating Thickness Levels
Thin Coating:
Provides basic protection in dry, mild environments (e.g., indoor use). However, it's vulnerable to moisture and mechanical damage, leading to faster corrosion in complex environments.
Moderate Thickness:
Offers a good balance between cost and performance. Suitable for most urban infrastructure and light industrial use, resisting common agents like oxygen, water, and weak acids. It ensures durability while controlling costs.
Thick Coating:
Delivers high-level protection in extreme environments (e.g., marine, chemical plants, desert). Withstands salt, acid, alkali, and physical stress, ensuring long service life and reducing maintenance.
Standards and Testing Methods
(1) Thickness Standards
Industry standards set minimum coating thickness:
CJ/T120-2016: Requires≥0.30 mm for DN≤65 mm,≥0.35 mm for DN≥80 mm (water supply).
GB/T23257-2009: Inner wall 150–500μm, outer wall 250–500μm (drainage systems).
In highly corrosive environments, enterprises may adopt stricter internal standards.
(2) Detection Methods
Magnetic Method: Widely used, fast, and accurate for non-magnetic coatings on steel.
Electromagnetic Induction: Detects coating thickness based on changes in induced current.
Ultrasonic Method: Measures wave travel time in coatings; suitable for multi-layer or thick coatings.
Proper calibration and skilled operation are essential for accurate measurements.
How to Choose the Right Coating Thickness
Selection depends on:
Environment: Mild (thin), general (moderate), or severe (thick).
Cost: Thin coatings save costs but may reduce lifespan in harsh environments.
Service Life Expectations: Long-term use requires thicker coatings despite higher initial investment.
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