Comparison of anti-corrosion technologies for galvanized steel pipes
release time：
2025-06-13 17:34
Ⅰ. Characteristics and application scenarios of cold galvanizing process
1. Process principle: zinc atoms are deposited on the surface of steel pipes through electrolytic reaction to form a dense coating of 5-15 microns
2. Advantages: smooth and beautiful surface, suitable for complex components; low production cost, energy consumption is only 30% of hot-dip galvanizing
3. Limitations: the coating has weak bonding strength, and the zinc layer is prone to fall off in humid or acidic and alkaline environments
4. Typical applications: mildly corrosive environments such as indoor steel structures, furniture hardware, and electrical chassis
Ⅱ. Characteristics and application scope of hot-dip galvanizing process
1. Technical points: immerse the steel pipe in 450℃ molten zinc liquid to form an alloyed coating of 50-100 microns
2. Core advantages: the zinc-iron alloy layer has extremely strong adhesion, and the outdoor service life can reach more than 20 years
3. Cost factors: large equipment investment, high energy consumption, and the cost per ton is 40%-60% higher than cold plating
4. Applicable fields: transmission towers, bridge structures, offshore platforms and other harsh corrosive environments
III. Design specifications and selection recommendations for zinc layer thickness
1. Thickness standard: ISO 1461 stipulates that the minimum average thickness of hot-dip galvanizing is 55 microns, and ASTM A123 proposes graded thickness requirements for cold-dip galvanizing
2. Environmental matching principle:
- 15 micron cold-dip galvanizing can be used in C1-C2 corrosive environments (dry indoors)
- 50 micron or more hot-dip galvanizing is required for C3-C4 environments (industrial atmosphere, coastal areas)
- C5-M grade (chemical industry, offshore platforms) requires 85 micron or more hot-dip galvanizing with sealing treatment
3. Economic balance: Under the premise of meeting the anti-corrosion life, the optimal thickness solution is determined through accelerated corrosion tests
IV. Key points for process selection decisions
1. Service life requirements: The durability of hot-dip galvanizing is 3-5 times that of cold-dip galvanizing
2. Initial investment budget: The investment in cold-dip galvanizing equipment is about 1/5 of that of hot-dip galvanizing
3. Environmental considerations: The hot-dip galvanizing process needs to be equipped with an acid mist treatment system, and the cold-dip galvanizing wastewater contains heavy metals and needs special treatment
4. Maintenance cost evaluation: Hot-dip galvanizing structures are usually maintenance-free, and cold-dip galvanizing requires regular coating protection
Combining technical indicators and economic factors, the process selection of galvanized strip pipes needs to be systematically evaluated based on the specific service environment, design life and full-cycle cost. In the field of major infrastructure, hot-dip galvanizing is still the preferred solution to ensure long-term corrosion protection; for short-term use or indoor components, cold-dip galvanizing can provide more cost-effective protection.
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