How many kinds of greenhouse materials are there?

Classification of greenhouse steel

At present, the following materials are commonly used by regular greenhouse companies:

Shape: square tube, round tube, elliptical tube, a few-shaped steel

Material: Most domestic steel pipes are made of steel inside and hot-dip galvanized outside

Galvanized steel pipe: divided into hot-dip galvanized standard pipe (national standard pipe) and galvanized coiled pipe (with pipe)

Hot-dip galvanized standard tube: national standard black tube + hot-dip galvanized

Galvanized (aluminum) zinc strip tube: (aluminum) galvanized sheet coil welding forming (galvanized strip tube and aluminized zinc strip tube) are all coiled tubes

Different use of material shape

Square tube: It is generally used on the column of the smart greenhouse. This general specification is 70*50, 50*100 or other larger square tubes. Smaller square tubes such as 50*50 are used on the horizontal rods of the greenhouse.

Round tube: used to build the frame of the greenhouse. It is a secondary load-bearing structure. After the force is applied, the force is transmitted to the main load-bearing structure. It is the skeleton of the greenhouse. The common models are generally φ25 and φ32.

Oval tube: Oval tube is a new product launched in recent years. Compared with round tube, it is particularly resistant to pressure. However, because the existing oval tube is made of galvanized strip, the anti-corrosion performance is inferior to that of round tube, which is only selected in some regions .

Shaped steel: It is mostly used on the top of smart greenhouses to form a shape of steel frame. The advantage is low cost, but it is less stable than square tubes. It is mostly used in areas where the force requirements are not high.

Material and service life of steel pipe

Most domestic steel pipes are made of steel inside and hot-dip galvanized outside. Hot-dip galvanizing is for anti-corrosion and increase service life. The specific service life depends on four aspects.

The material of steel: from the process, it can be divided into hot-dip galvanized national standard pipe, galvanized coiled pipe, and hot-dip galvanized molded parts after black pipe processing.

After the greenhouse is built, whether the steel pipe is within the design range: If natural disasters such as unforeseen blizzards, typhoons, etc. occur, the steel pipe’s force will definitely exceed the design value and reduce the service life.

The user's maintenance of the steel pipe: whether to add other objects that exceed the load of the steel pipe on the steel pipe, whether the environment where the steel pipe is located is wet for a long time, etc.

How much galvanized steel pipe is, and more galvanized steel has good anti-corrosion effect and long service life. Generally speaking, the service life of steel pipes of average quality is at least 10 years under normal use, and high-quality steel pipes of big brands are generally 15 to 20 years, and those with good maintenance and relatively large galvanization can even reach 30 years. Service life.

Factors affecting the quality of steel pipes

The amount of galvanized steel is extremely susceptible to air oxidation and rust, so anti-corrosion measures must be adopted. At present, the most commonly used anti-corrosion measure is to galvanize the surface of the steel pipe. The amount of galvanizing determines the corrosion resistance. The more galvanizing, The better the workmanship, the better the quality of the steel pipe. But the more galvanizing, the higher the cost.

The wall thickness of the steel pipe. The steel pipe is a stressed member, and it must have a force requirement. The thicker the pipe wall of the steel pipe, the better the force performance and the better the quality. However, the thicker the relative pipe wall, the cost Higher.

Process description of galvanized steel pipe

Rack plating: It is also hanging plating, with good quality, high zinc loading, and strong anti-corrosion ability. The process flow is roughly that the steel pipe is pickled, and after the impurities on it are washed off, the entire steel pipe is immersed in the zinc bath for several times. A few seconds of lifting cycle, take it out and then cool down. The amount of zinc on the steel pipes of the hanging galvanizing process reaches 400~600 grams, and the useful life of the hanging galvanized steel pipes is 30 years. Nowadays, a large number of hanging galvanized steel pipes are used in the steel, high-speed rail and infrastructure of the country’s major projects. The large pieces of galvanized steel used in the greenhouse Crafts, such as truss.

Blow plating: also need to go through pickling and dipping bath, but after it is lifted up, it will pass through a device to remove the excess zinc before the zinc is completely attached to the steel pipe, but the amount of zinc is slightly lower The current standard is about 200 grams, which is nearly double the amount of zinc applied to the zinc plating process. The steel pipe of this process has low cost and can be used for 15 to 20 years. It is cost-effective and is used as a common galvanizing process.

Galvanized/aluminum strip: steel raw materials are plated in advance and then made into tubes. The amount of galvanization is low and the corrosion resistance is poor. The amount of galvanization per square meter is 50 grams. It will rust in 2 to 3 years. It is not recommended for use in greenhouses.

Cold plating: Since the country's high requirements for environmental protection, cold plating has gradually withdrawn from the stage of history. Now cold plating is basically not used, and it is a process that has been eliminated.

Plastic coating: After the hot-dip galvanizing process is completed, plastic coating on the outside of the galvanized pipe continues to increase the corrosion resistance. However, the average cost per ton of steel will increase by about 2,000 yuan. The cost is too high and has not been used.

How to recognize the quality of steel pipes with the naked eye

Mainly identify the anti-corrosion of the surface

Rack plating: Due to the thick galvanized layer, the color is slightly darker than that of blow plating and strip tube;

Galvanized strip: The amount of zinc is low, the newly produced surface is bright, and it will penetrate a little black after a period of time.