Welcome to Shandong Zhishang Steel Co., Ltd.
Welcome to Shandong Zhishang Steel Co., Ltd.
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Hot-dip galvanized pipe is a special steel pipe, its surface is covered with a layer of galvanized layer, which is mainly to improve the corrosion resistance of the steel pipe. This steel pipe is mainly divided into two types: hot dip galvanized and electric galvanized. Among them, the coating of hot galvanizing is thicker, and the cost of electric galvanizing is lower, but the surface may not be as smooth as hot galvanizing.
The production process of hot-dip galvanized pipe involves the reaction of molten metal with iron matrix to form an alloy layer. In this way, the substrate and the coating can be tightly bonded together. Specifically, the process of hot dip galvanizing begins with pickling the steel pipe to remove the iron oxide on the surface of the steel pipe. After pickling, the steel pipe is washed in an aqueous solution containing ammonium chloride or zinc chloride before being fed into a hot dip bath. The advantages of hot dip galvanizing lie in its uniform coating, strong adhesion and long service life. In this process, the steel tube matrix and the molten bath will undergo complex physical and chemical reactions to form a corrosion-resistant zinc-iron alloy layer. This alloy layer is closely combined with the pure zinc layer and the steel tube matrix, and therefore has strong corrosion resistance.
In practical applications, the iron pipes commonly used in gas, greenhouses and heating systems are also galvanized. However, when the galvanized pipe is used as a water pipe, a large amount of rust and scale may be produced in the pipe. This will not only contaminate the sanitary ware, but also may breed bacteria because the tube walls are not smooth. In addition, rust may also lead to high levels of heavy metals in water, posing a serious threat to human health. Therefore, from the 1960s and 1970s, developed countries in the world began to develop new pipes and gradually banned the use of galvanized pipes. China's Ministry of Construction and other relevant departments also issued a clear document in 2000, prohibiting the use of galvanized pipes. Now, the cold water pipe in the new community has rarely used galvanized pipe, but the hot water pipe in some communities still uses galvanized pipe.
Can be hot galvanized or cold galvanized
Galvanized pipe can be hot galvanized or cold galvanized.
Hot-dip galvanized pipe is the steel pipe immersed in high temperature molten zinc liquid to form a layer of solid zinc-iron alloy coating, which has high adhesion and can provide excellent corrosion resistance, while cold galvanized pipe is coated with a thin layer of zinc on the surface of the steel pipe by electrochemical method, the coating thickness is thin, and the corrosion resistance is relatively poor.
The coating of hot-dip galvanized pipe is thicker, generally reaching 50 to 120 microns, which can effectively block the erosion of external oxygen and water and provide a longer protective effect, while the coating of cold galvanized pipe is relatively thin, generally between 5 and 30 microns.
Galvanized pipe as a widely used material, its production and use in the process will indeed encounter some technical problems. Fortunately, as technology advances, there are solutions to these problems. At the same time, due to fluctuations in market demand, the price of galvanized pipes will also be affected to a certain extent, which is a common phenomenon in the market economy.
In the production process, steel leakage defect is a common problem. In order to reduce production costs and improve the strength of steel, manufacturers often add a higher proportion of silicon to steel-based materials. However, if the amount of silicon is too much, it will lead to an increase in the surface tension of the steel, which reduces the wetting ability of the steel plate to the zinc liquid and affects the galvanizing effect. In addition, silicon is easy to react with oxygen to produce silica at high temperatures, and if these acidic substances cannot be effectively removed, steel leakage defects will be formed during the galvanizing process.
In order to solve this problem, continuous hot-dip galvanizing process of hot-rolled steel strip without pickling can be adopted. This process is characterized by feeding the steel strip directly into the reduction furnace without going through the pickling step, and increasing the volume fraction of hydrogen to more than 20% to reduce the possibility of oxidation. At the same time, in the process of hot dip galvanizing, the adhesion of the coating can be significantly improved by forming Fe-Al-Zn alloy layer on the surface of the steel strip, so as to effectively eliminate steel leakage defects. These countermeasures are very worthy of reference for galvanized pipe manufacturers.
Another problem is the loss of the zinc layer, which is usually caused by the low heating value of the gas in the pentoxide furnace or the oxidation atmosphere caused by pressure fluctuations. In order to solve this problem, several countermeasures can be taken:
a. Choose a gas burner with better combustion performance to ensure that the pressure of air and gas is stable in an appropriate range;
b. Control the fluctuation range of gas heating value to ensure that its fluctuation does not exceed ±5%;
c. In the open flame heating, the temperature of the forge should be maintained above 1000℃;
d. If the forging furnace without burner preheating is used, its temperature should be maintained above 800℃;
e. The temperature of the strip steel when leaving the pentoxide furnace should be controlled below 650℃.
Through these measures, the zinc layer can be effectively prevented from falling off and the quality of galvanized pipe can be guaranteed. In short, although galvanized pipes may encounter some problems in the production and use of the process, but through scientific methods and technological innovation, these problems can be solved. At the same time, producers also need to pay close attention to market dynamics in order to better cope with the challenges posed by price fluctuations.
First, the difference between galvanized pipe and steel pipe
Galvanized pipe is a kind of pipe that covers the surface of ordinary steel pipe with zinc layer, which is characterized by good corrosion resistance and smooth surface. The steel pipe is not galvanized, and its surface anti-corrosion ability is weak and easy to be corroded.
Second, the durability of galvanized pipe and steel pipe comparison
1. Corrosion resistance
Because the galvanized pipe has been galvanized, it has good corrosion resistance and long service life; The untreated steel pipe is easy to be corroded and has a short service life.
2. Carrying capacity
The bearing capacity of the steel pipe is stronger than that of the galvanized pipe, because the surface of the steel pipe has no galvanized layer, and the material is relatively stronger.
3. Use environment
In wet environments, galvanized pipes are more durable than steel pipes because the zinc layer prevents moisture from entering the pipe, thereby protecting the pipe from damage.
In a dry environment, the life of the steel pipe is longer, especially in the absence of acid and alkali corrosion, and the service life is longer.
Third, how to choose galvanized pipe and steel pipe
1. Select according to the use environment
In humid environment, it is recommended to choose galvanized pipe; In a dry environment, steel pipe is recommended.
2. Select based on load requirements
If you need to carry a larger weight of items, it is recommended to use steel pipe, because it has a stronger load capacity.
3. Select based on the actual situation
Galvanized pipe is a material that is often used in daily life. So, is this material made of iron or steel?
First of all, we need to make it clear that galvanized pipes are actually made of steel. This pipe is also known as galvanized steel pipe, which can be divided into two types: hot dip galvanized and electric galvanized. If it is a hot-dip galvanized pipe, the galvanized layer will be thick and uniform, so its service life will be longer. However, if it is electrically galvanized galvanized pipe, although its cost is lower, its surface is not particularly smooth, and its corrosion resistance is not as good as the former. Therefore, we recommend to try to choose hot-dip galvanized galvanized pipe.
Secondly, there are many galvanized pipe manufacturers sold on the market, and we need to understand the quality of the products when buying, so as to ensure that the quality is more guaranteed.
Next, let's talk about the difference between galvanized pipes and stainless steel pipes.
First of all, the meanings of the two are completely different. Galvanized pipe is made by welding, there are mainly two types of hot dip galvanized and electric galvanized. The stainless steel pipe is actually a long round steel.
Secondly, the scope of application of the two materials is also different. Galvanized pipe can be widely used in construction, chemical, electric power, automobile, bridge and other industries. The stainless steel pipe is mainly suitable for chemical, food, petroleum and other industries, in addition, it can also be used for the manufacture of some parts.
Finally, we need to pay attention to the following points when using galvanized pipes:
In the process of use, do not use sharp objects to knock on the surface, otherwise it may cause cracks. At the same time, try to avoid letting the material come into contact with easily corroded products to prevent corrosion.
When dealing with the gap between the pipes, the sleeve can be installed, generally the thickness of the sleeve is greater than 10 mm, and the gap is filled with insulation material.
