First, the source of steel
High-quality racking suppliers will use Baosteel Q235 rolled steel or similar high-quality steel, while poor suppliers often offer low-quality steel from smaller mills. It is suggested that users can judge by the following. methods:
1.Please ask the supplier to provide the corresponding steel warranty, and confirm whether the supplier purchases this batch of materials through the telephone number on the warranty.
2.Entrust authoritative testing institutions to test the mechanical properties of steel. Generally speaking, the yield strength of high-quality Q235 material is often not less than 275Mpa, and the tensile strength is often more than 400Mpa.
Second, material thickness and column side width size
Some suppliers will put forward to customers the view that the wider the front of the column, the better the strength of the column, which mislead users to ignore the attention to the thickness of the material and the width of the side of the column.
1.In most cases, the force on the column is mainly related to the cross-sectional area of the column.
2.The thickness of the material is provided to customers in accordance with the 10% deviation limit of China’s domestic standard. For example, the thickness of the 2mm material is only 1.8mm for the customer. If this happens to a large amount of steel in one project, the structural stability of the entire shelf will be greatly affected.
In this case, It is necessary to require the manufacture to provide the warranty, and the mechanical properties and chemical composition of the material can be tested at the same time, and compared with the warranty.
Third, Secondary structural materials
In the complex racking structure, some manufactures often provide materials that meet the requirements on the main materials that users are more concerned about, such as beams, columns, while minimizing other structural materials that users tend to ignore for cost-saving considerations, such as connectors and poll rods.
These structures are important components to ensure the strength, stiffness and stability of the shelves. The reduction of these materials will lead to the overall strength of the shelves can not be guaranteed, especially the shelves with seismic requirements.
In this case, It is necessary to require the manufacture to provide racking mechanics calculation report. Of course, some manufacturers will submit false reports to customers in order to obtain orders. Customers can find an authoritative third-party accounting institution for screening.
