The steel tube has a hollow section, and its length is much larger than that of the steel with diameter or circumference.
According to the production process, it is divided into seamless steel pipe and welded pipe, of which two kinds of seamless steel pipe are hot rolling and cold rolling (drawing). The welded pipe is divided into straight seam welded pipe and spiral seam welded pipe.
Steel pipe is not only used for transporting fluid and powdery solid, exchanging heat energy, manufacturing mechanical parts and containers, but also an economic steel. The use of steel pipe to build structural grid, pillar and mechanical support can reduce weight, save metal 20 to 40%, and realize mechanized construction in factories. The manufacture of road and bridge with steel pipe can not only save steel products and simplify construction, but also greatly reduce the area of protective coating and save investment and maintenance costs.
According to the production method, the steel pipe can be divided into two main categories: seamless steel pipe and slotted steel pipe.
1, seamless steel tubes can be divided into hot rolled seamless pipes, cold drawn tubes, precision steel pipes, hot expansion pipes, cold spinning pipes and extruded pipes according to the production methods.
Seamless steel tubes are made of high quality carbon steel or alloy steel, and are divided into hot rolling and cold rolling (drawing).
2, welded pipes are divided into furnace pipe, electric welding (resistance welding) tube and automatic arc welding pipe because of its different welding technology. Because of its different welding forms, there are two kinds of welded pipe and spiral welded pipe, and the end shape is divided into circular welded pipe and special type (square, flat, etc.) welded pipe.
The welded steel pipe is made of the rolled tube shaped steel plate, which is welded by the seam or spiral seam. In the manufacturing method, it is divided into the welded pipe of low pressure fluid transportation, the spiral seam welded pipe, the direct coil welding pipe, the welding pipe and so on. Seamless steel pipe can be used in various industries such as liquid pressure pipes and gas pipes. Welded pipes can be used for water conveyance pipelines, gas pipes, heating pipes, electrical appliances pipes, etc.
Steel Pipe,Galvanized Steel Pipe,Stainless Steel Pipe,Carbon Steel Pipe HeBei GuangHao Pipe Fittings Co .,LTD (Cangzhou Sailing Steel Pipe Co., Ltd) , https://www.guanghaofitting.com
Second, avoid applying chlorine-containing fertilizer. Watermelon belongs to the avoidance of chlorine crops. The application of chlorine-containing fertilizers (such as ammonium chloride, potassium chloride, etc.) will affect the accumulation of sugar and make the taste of the melons lighter.
Three bogey excessive application of human excrement. Excessive human excrement can easily cause the plant to grow long, making it difficult to sit on the melon, and the melon skin is thick and sour.
Four bogey fertilize in the topsoil. Watermelon top dressing should pay attention to deep application, and timely cover soil after application, especially nitrogen fertilizer. If applied, nitrogen is easy to volatilize to produce ammonia gas, which harms the leaves and also reduces fertilizer efficiency.
Five bogey rainy weather fertilization. In the rainy weather, the air humidity is high, and the soil moisture content is high. At this time, fertilization is not only easy to lose the fertilizer, but also easily causes the watermelon to grow.
Six bogey fertilization sites are too close to the roots. The fertilization site of watermelon is generally about 10 cm away from the main root; it is too close to burn roots and affect plant growth.
Seven bogey when the drought is topdressing. The weather is dry and the soil moisture content is low. At this time, the application of chemical fertilizer will cause the cytoplasmic solution of the root cells to penetrate outward, causing the plant to be physiologically dehydrated and die.
They are divided into circular, square, rectangular and special-shaped steel tubes according to the section shape.
The material is divided into carbon structural steel pipe, low alloy structural steel pipe, alloy steel pipe and composite steel pipe.
It is divided into pipeline, engineering structure, thermal equipment, petrochemical industry, mechanical manufacturing, geological drilling, and high pressure equipment for use.
One should not apply a large amount of nitrogen fertilizer. A single application of a large amount of nitrogen fertilizer, the plant is very easy to grow, is not conducive to flowering and melon and fruit development. Before the watermelon was placed in the melon, the nitrogen nutrition was the main factor. After the melon was taken, the absorption of potassium increased sharply. The amount of nitrogen and potassium in the depilation stage of the melon was basically equal. The absorption of the melon in the expansion stage reached the peak, and the ripening stage of the melon was nitrogen. The amount of potassium absorbed was significantly reduced, and the amount of phosphorus absorbed was relatively increased. The ratio of nitrogen, phosphorus and potassium was 3.8:1:2.8 for seedling stage and 3.6:1 for 1.7:1 for 1.7, and the growth period for melon was 3.5: 1 : 4.6.
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