中文
Hot-dip galvanizing is a common method for metal corrosion protection. It immerses steel products in molten zinc liquid to form a zinc-iron alloy layer and a pure zinc layer on the surface of the steel, thus providing good corrosion protection. This method is widely used in the construction, automobile, power, communication and other industries to protect steel structures, pipelines, fasteners, etc.
The basic steps of hot-dip galvanizing process are as follows:
Degreasing and cleaning
The steel surface first needs to be thoroughly cleaned to remove grease, dirt and other impurities. This is usually done by immersing the steel in an alkaline or acidic solution followed by a cold water rinse.
Flux coating
The cleaned steel is then immersed in a 30% zinc ammonium solution at 65-80°C. The purpose of this step is to apply a layer of flux to help remove oxides from the surface of the steel and ensure that the molten zinc can better react with the steel.
Galvanizing
The steel is immersed in molten zinc at a temperature of about 450°C. The immersion time is usually 4-5 minutes, depending on the size and thermal inertia of the steel. During this process, the steel surface chemically reacts with the molten zinc.
Cooling
After hot-dip galvanizing, the steel needs to be cooled. Natural air cooling or rapid cooling by quenching can be selected, and the specific method depends on the final requirements of the product.
Hot-dip galvanizing is an efficient anti-corrosion treatment method for steel, offering significant benefits:
● Lower cost: The initial and long-term costs of hot-dip galvanizing are generally lower than other anti-corrosion coatings, making it an affordable choice.
● Extremely long service life: The galvanized coating can continuously protect the steel for more than 50 years and effectively resist corrosion.
● Less maintenance required: Since the galvanized coating is self-maintaining and thicker, it has low maintenance costs and a long service life.
● Automatically protects damaged areas: The galvanized coating provides sacrificial protection, and small areas of damage do not require additional repairs.
● Full and complete protection: Hot-dip galvanizing ensures that all parts, including hard-to-reach areas, are fully protected.
● Easy to inspect: The condition of the galvanized coating can be assessed by simple visual inspection.
● Faster installation: Hot-dip galvanized steel products are ready to use when they arrive at the jobsite, with no additional surface preparation or inspection required.
● Fast application of full coating: The hot-dip galvanizing process is fast and not affected by weather, ensuring a quick turnaround.
These advantages make hot-dip galvanizing an ideal choice for steel corrosion protection, which not only improves the service life and performance of steel, but also reduces overall costs and maintenance workload.
The exposed surfaces of the end fittings(including flange faces) of the CDSR oil suction and discharge hoses are protected by hot-dip galvanizing in accordance with EN ISO 1461, from the corrosion caused by seawater, salt mist and transmission medium. As the oil and gas industry continues to pursue sustainable development, the application of hot-dip galvanizing technology not only improves the corrosion resistance of equipment and extends its service life, but also indirectly reduces resource consumption and waste generation by reducing the frequency of equipment replacement due to corrosion.
Date: 28 Jun 2024