How Is The Surface of The Anchor Chain Treated?
As a core component of the ship's mooring system, the performance of the anchor chain depends not only on the material strength and specification grade, but also on the surface treatment process, which is a key factor that directly affects its corrosion resistance, service life and maintenance cost. This article systematically sorts out the three mainstream surface treatment technologies of the anchor chain-original color treatment, black paint spraying and hot-dip galvanizing process, and conducts in-depth analysis from the aspects of technical principles, performance differences, and scene adaptability.
1. Original color anchor chain: economical and efficient
Technical definition: Original color anchor chain refers to the original color state of the metal without any chemical treatment or coating treatment. After the original steel is cut, heated and braided, and welded to remove thorns, the surface presents a natural silver-gray color, and there will be some residual trace xide scale. Then, the surface is shot blasted to remove surface impurities and improve the cleanliness before it can be shipped as an original color finished product.
Core advantages
Reduce costs: Eliminate the processes of varnishing and drying, and reduce manufacturing costs by 5%-10%.
Efficient delivery: The production cycle is shortened by 10%, meeting the needs of urgent orders and projects.
Visible quality: Another great advantage is that users can clearly see the quality of the product and the surface quality, which is a good test for the quality of the anchor chain. For this reason, many customers directly choose the original color, which can see the quality of the anchor chain more clearly.
Performance limitations
Weak corrosion resistance: In the seawater environment, the rust rate of carbon steel original color anchor chain reaches 0.1 mm/year, and the life span will be shortened. If conditions permit, rust removal and anti-rust oil treatment are required every 3-6 months, and labor costs are greatly increased.
Typical application scenarios
Low corrosion environments such as inland cargo ships and freshwater aquaculture ships, temporary anchoring equipment, non-critical structural parts
Short-term construction marine engineering projects (cycle <1 year).
2. Black paint anchor chain: high surface cleanliness
Technical definition: After shot blasting, the original color anchor chain is dipped in black paint and dried. In the past, many anchor chain factories used asphalt paint. Now large manufacturers use water-based paint with high environmental protection performance, which is non-toxic and odorless and dries quickly.
Technological breakthrough
Anti-corrosion upgrade: Salt spray tests show that high-quality black-painted anchor chains can resist corrosion for 500-800 hours in general waters, which is higher than original color anchor chains.
Visual uniformity: The black water-based paint coating conforms to the standardized aesthetics of the shipbuilding industry and reduces light reflection interference.
Application pain points
Coating fragility: The thin black paint film of the anchor chain is easily worn, and the wear rate of the friction area is 0.5μm/time. Sometimes, some parts fall off when transported to the customer.
Maintenance continuity: After the paint film is damaged, local paint repair is required, otherwise the rust rate will be accelerated by 2-3 times.
Covering defects: Black paint has the effect of filling the uneven surface. Some manufacturers' anchor chain surface shot blasting process is not done well. After being stained with black paint, some insufficient welding points and surface scratches will be covered up. This is why many customers do not choose black paint.
Applicable scenarios
Anchor chains for ocean-going fishing vessels and engineering vessels (annual corrosion <0.3 mm) that do not need to immerse the anchor chain in water for a long time, temporary mooring equipment in ports, floating bridges and other intermittent water inflow scenarios. There are also small and medium-sized ships that are cost-sensitive but require certain corrosion resistance.
3. Hot-dip galvanized anchor chain: suitable for long-term immersion in water
Technical principle: Through 450-460℃ molten zinc liquid immersion plating, a composite structure of zinc-iron alloy layer (thickness ≥60μm) and pure zinc layer (thickness ≥50μm) is formed. This process makes the surface hardness of the anchor chain reach HV200-250, and the salt spray resistance reaches more than 2000 hours.
Performance advantages
Super corrosion resistance: In tropical waters (water temperature >25℃), actual measurements show that the service life of hot-dip galvanized anchor chains can reach 15-20 years, which is three times that of black paint anchor chains.
Strong self-repairing ability: The sacrificial anode protection of the zinc layer can automatically repair tiny scratches.
Easy maintenance: only check the zinc layer thickness once every 5 years, no frequent painting is required.
Economic analysis
Although the initial cost is 20-30% higher than the original color anchor chain, the full life cycle cost is reduced by 35%-50%, especially suitable for anchoring projects such as ocean-going ships and deep-sea platforms that need to be immersed in water for a long time.
Application scenarios
Ocean-going merchant ships, scientific research ships and other long-term offshore operation ships, offshore wind power installation ships, semi-submersible platforms and other special equipment, Arctic routes, tropical waters and other extreme corrosion environments, etc. need to be immersed in water for a long time, and the anchoring system for operations with relatively high corrosion requirements.
4. How to choose surface treatment
The prices of original color anchor chain and black anchor chain are basically the same, and we give customers the same price, so many customers directly choose the principle anchor chain. If you like the black anchor chain looks good and the construction period is not very urgent, you can choose the black paint anchor chain.
If the project needs to be immersed in water or seawater for a long time, you must choose hot-dip galvanized anchor chain, combined with anode protection technology, which can better extend the service life of the chain.
Conclusion: Anchor chain is the guardian of the ocean
Anchor chain technology has been continuously upgraded, from simple level 2 and level 3 to level R, and now to the R6 level technology breakthrough. The surface treatment technology of anchor chain has also been upgraded synchronously, reflecting the unremitting pursuit of safety and efficiency in marine operations and the shipping industry. When purchasing anchor chains, users need to comprehensively consider environmental corrosiveness, equipment life cycle cost, and operation and maintenance capabilities to achieve the best balance between safety and economy.