When building a greenhouse, is it more reliable to use thicker steel pipes?

1.The real relationship between steel pipe thickness and greenhouse performance

(I) Load-bearing and wind resistance: thickness is not the only determining factor

The thickness of steel pipes does affect the load-bearing capacity of greenhouses. For example, snow accumulation in winter will bring considerable pressure to the roof of the greenhouse. When planting crops such as cucumbers and tomatoes that need to be hung, their weight must also be borne by the greenhouse frame. At the same time, the thickness of steel pipes is also related to the wind resistance of greenhouses. But don't think that thickness is the only key to determining these two performances.

The role of structural design is equally important. For example, if the span of the greenhouse is large, it is not enough to increase the thickness of the steel pipe. Reasonable setting of internal columns can greatly enhance the load-bearing and wind resistance performance. In the snowy northern regions, when the span of the greenhouse exceeds 12 meters, adding a few columns appropriately can avoid deformation problems caused by thickening the steel pipe alone due to insufficient overall rigidity. There is also an arched curvature. Scientific design can better disperse pressure and make the greenhouse more stable. If the column spacing is appropriate, the greenhouse can also be more evenly stressed.

In addition, material strength cannot be ignored. There are different grades of steel, such as the common Q195B, Q235B, etc., with different strengths. Only by choosing the right steel with the right strength and a reasonable thickness can the greenhouse perform well in terms of load-bearing and wind resistance. Just like in the typhoon area in the south, improving wind resistance through structural design such as support reinforcement and ground anchor bolts is much more effective than simply thickening the steel pipe.

(ii) Corrosion resistance: The quality of the galvanized layer is more important than the thickness of the steel pipe

For hot-dip galvanized steel pipes, the anti-corrosion performance mainly depends on the thickness of the zinc layer, not the thickness of the steel pipe itself. According to the national standard, the zinc layer thickness must reach 60-85μm. Imagine if the zinc layer is not sprayed evenly or the thickness is not enough, even if the steel pipe itself is 3.0mm thick, once the zinc layer is damaged, air and moisture will easily corrode the steel, causing rust, and the life of the greenhouse will be greatly shortened. On the contrary, a 2.0mm thick steel pipe, as long as the zinc layer meets the standard (60-85μm on both sides), can be used normally for more than 10 years in an ordinary greenhouse environment, such as not in a high humidity or acidic soil area. Therefore, when choosing a steel pipe, it is much more important to pay attention to the quality of the galvanized layer than to simply pursue thickness.

(iii) Cost and construction: Increased thickness brings a double burden

Material cost: For every 0.5mm increase in the thickness of the steel pipe, the cost may increase by 15%-20%. Taking a one-acre greenhouse as an example, if the thickness of the steel pipe is increased from 2.0mm to 2.5mm, the cost of the steel pipe alone may cost several thousand yuan more. For farmers or enterprises that build greenhouses on a large scale, this is not a small amount. Therefore, when choosing the thickness, you have to consider the impact of the increase in material costs on the overall budget.

Construction difficulty: The steel pipe is too thick, so the weight is naturally large. It is very difficult to operate during processing and bending, and special equipment and skilled workers are required. During welding and installation, higher requirements are placed on equipment, and the labor intensity of workers will also increase. Moreover, when the overall greenhouse frame becomes heavier, the load-bearing requirements for the foundation will also increase, and the foundation may have to be reinforced, which indirectly increases the construction cost.

2.Reasonable selection of steel pipe thickness in different scenarios

(I) Ordinary greenhouse (vegetables, flowers)

Span ≤ 8 meters: For this type of greenhouse with a small span, it is recommended to use 1.5-2.0mm thick hot-dip galvanized steel pipes. Under normal climate conditions in the north and south, it can meet the requirements of load-bearing and wind resistance, while taking into account cost and durability, and has a high cost-effectiveness. Whether it is common leafy vegetables or flowers that do not require high environmental requirements, it can provide a stable growth space.

Span 8-12 meters: When the span is in this range, it is recommended to use 2.0mm thick steel pipes and columns. Because the span increases, the pressure on the steel pipe will also increase. A 2.0mm thick steel pipe alone may bend. Reasonable setting of columns can enhance the mid-span load-bearing, prevent the steel pipe from deforming, and ensure the stability of the greenhouse structure.

(II) Special environment greenhouse (high temperature, high humidity, heavy snow area)

High humidity environment (such as aquatic nursery shed): In a high humidity environment like an aquatic nursery shed, steel pipes are more susceptible to corrosion. Hot-dip galvanized steel pipes are preferred, and the thickness should be kept at 2.0mm. However, it is not enough to just choose the right steel pipe. Strengthening ventilation design is critical. Good ventilation can reduce the adhesion of condensed water on the surface of the steel pipe, reduce the degree of corrosion, extend the service life, and create a stable and reliable environment for aquatic seedling cultivation.

Heavy snow area (snow depth ≥ 30cm): In heavy snow areas, snow accumulation puts a lot of pressure on the greenhouse. In this case, the thickness of the steel pipe can be increased to 2.5mm, and the distance between the columns can be reduced to within 3 meters, and then the arch frame can be reinforced with diagonal braces. A multi-pronged approach can greatly enhance the greenhouse's ability to withstand the pressure of snow accumulation, prevent it from being crushed, and ensure the safety of crops in the greenhouse.

(III) Economical temporary greenhouse

If the greenhouse is only used for 1-2 years, such as for short-term seedling cultivation, choose a steel pipe with a thickness of 1.2-1.5mm. Although the steel pipe is thin, the thickness of the zinc layer must meet the standard. Even if it is used for a short period of time, if anti-corrosion is ignored, the steel pipe will quickly rust, affecting normal use. As long as the quality of the zinc layer is guaranteed, this thickness can meet basic needs and effectively control costs within 1-2 years.