At present, the following main materials are commonly used in regular greenhouse greenhouses:
Shape: square tube, circular tube, elliptical tube, and cross shaped steel
Material: Most domestic steel pipes are internally made of steel and externally hot-dip galvanized
Galvanized steel pipes: divided into hot-dip galvanized standard pipes (national standard pipes) and galvanized coil pipes (with pipes)
Hot dip galvanized standard pipe: national standard black pipe+hot-dip galvanized
Galvanized strip pipe: galvanized sheet rolled and welded into shape
2.The respective uses of steel pipes for greenhouse structures
1.Square tube: Generally used on the pillars of intelligent greenhouses, this type of square tube is generally 70 * 50, 50 * 100, 100 * 100, 120 * 120, 150 * 150 or other larger specifications. Smaller square tubes such as 50 * 50 are used on the horizontal rod of the greenhouse.
2.Circular tube: A frame (column, inclined beam, longitudinal tie rod) used to build a greenhouse, or a secondary load-bearing structure that transmits force to the main load-bearing structure after being subjected to force. It is the skeleton of a greenhouse, and common models are generally φ 25 φ 32 φ 48 φ 60.
3.Elliptical tube: Elliptical tube is a new product launched in recent years. Compared to circular tubes, it has particularly good pressure resistance. However, due to the fact that existing elliptical tubes are made of galvanized tape, their anti-corrosion performance is inferior to that of circular tubes, and they are only selected in a few regions. Elliptical tubes are generally made by flattening and bending hot-dip galvanized square tubes.
4.Cross shaped steel: It is commonly used on the top of intelligent greenhouses to form a cross shaped steel skeleton. The advantage is low cost, but compared to square tubes, it has poorer stability. Mainly used in areas with low stress and anti-corrosion requirements.
5.Steel pipe wall thickness: ordinary planting shed, round pipe φ 25 φ 32 is the main structure, with a thickness mostly ranging from 1.5 to 2.75mm
Ordinary breeding shed, elliptical tube 25 × 50mm, 30 × 60mm, 30 × 70mm, 30 × 80mm, 40 × 80mm
3.Material and service life of greenhouse steel pipes
Most steel pipes in China are made of steel inside and hot-dip galvanized outside. Hot dip galvanizing is used to prevent corrosion and increase service life. The specific service life depends on four aspects
—Material of steel: Technically, it can be divided into hot-dip galvanized national standard pipes, galvanized coil pipes, and hot-dip galvanized formed parts after processing black pipes
After the greenhouse is built, is the stress on the steel pipe within the design range? If unforeseeable natural disasters such as blizzards and typhoons occur, it will definitely cause the stress on the steel pipe to exceed the design value and reduce its service life.
—Maintenance of steel pipes by users: whether other objects exceeding the load of the steel pipe are added to the steel pipe, and whether the environment where the steel pipe is located is humid for a long time
The amount of galvanized steel pipe and the amount of galvanized steel have good anti-corrosion effect and long service life. Generally speaking, steel pipes of average quality have a service life of at least 10 years under normal use, while high-quality steel pipes of large brands generally have a service life of 15-20 years. Those with good maintenance and a large amount of galvanizing can even reach a service life of 30 years.
4、 Factors affecting the quality of steel pipes:
1) The amount of galvanized steel pipe is extremely susceptible to air oxidation and rusting, so anti-corrosion measures must be taken. Currently, the most commonly used anti-corrosion measure is galvanized on the surface of the steel pipe. The amount of galvanized steel determines its corrosion resistance. The more galvanized steel is, the better the process, and the better the quality of the steel pipe. However, the more galvanizing required, the higher the cost.
2) The wall thickness of a steel pipe is a load-bearing component, and it must have load-bearing requirements. The thicker the wall of the steel pipe, the better its load-bearing performance, and naturally the better its quality. However, the thicker the pipe wall, the higher the cost.
5、 Process Description of Galvanized Steel Pipe
1) Hanging plating: also known as hanging plating, it has the best quality, the highest amount of zinc applied, and the strongest anti-corrosion ability. The process roughly involves pickling the steel pipe, removing impurities from it, and immersing the entire steel pipe in a zinc pool. After several lifting cycles of more than ten seconds, it is taken out and cooled down. The zinc content on the steel pipe of the hanging zinc process reaches 400-600 grams, and the service life of the hanging galvanized steel pipe is 30 years. Currently, a large number of hanging galvanized steel pipes are used in national major projects such as steel, high-speed rail, and infrastructure. The galvanizing process is used for large parts in greenhouses, such as trusses and brackets.
2) Blow plating: It also requires acid washing and soaking in a zinc bath, but after lifting it up, it will go through a device to remove excess zinc before it is fully attached to the steel pipe. However, the amount of zinc added is slightly lower, with the current standard of around 200 grams, which is nearly twice the amount of zinc added compared to the hanging zinc process. This process has a low cost of steel pipes, a service life of 15-20 years, and high cost-effectiveness, As a commonly used galvanizing process.
3) Galvanized strip: pre coated with steel raw materials, then made into pipes, with low galvanizing amount and poor anti-corrosion ability. The amount of galvanizing is 50 grams per square meter, which will rust in 2-3 years. It is not recommended to use it in greenhouses.
4) Plastic coating: This process is a process that continues to increase corrosion resistance by coating the galvanized pipe with plastic after the completion of hot galvanizing. However, the average cost per ton of steel will increase by about 2000 yuan, which has not been used in greenhouse engineering due to its high cost.
5、 How to identify the quality of steel pipes with the naked eye
Mainly identify the anti-corrosion of the surface
Hanging plating: Due to the thickness of the galvanized layer, the color is slightly darker than that of blowing plating and tape plating;
Galvanized strip: The zinc content is low, and the newly produced surface is bright, and after a period of time, it will show a bit of black. Secondly, professional equipment can use a zinc layer measuring instrument for professional measurements.
6、 Greenhouse steel pipe production cycle
If there are steel pipes in stock, there is no need for a production cycle. If there is a large quantity, please provide a production cycle of 3-7 days in advance.
7、 Greenhouse steel pipe Transportation cycle
To South Africa: 45 days
To the Middle East: 30 days
To South America: 45 days
To North America: 30 days
To Russia: 7 days
To Europe: 45 days
To Korea: 5 days
To Japan: 5 days
To Vietnam: 15 days
To Thailand: 15 days
To India: 30 days
To Indonesia: 15 days
To Singapore: 15 days
8. Application Engineering Cases
Project name:Egypt Million Ferdan Land Improvement Project
Supplied products:Square steel pipe, circular steel pipe
Supply quantity: 70000 tons