Square and Round Curl Analysis of Closed Steel Drums
Ma Jianxiang
In China, there are two main types of 200-liter closed steel drums: square (rectangular) and round. From the perspective of more than a dozen steel drum manufacturers in Xinjiang, both square and round designs coexist in the market. But what are the differences in performance between these two types? How do they compare in terms of durability and safety? Based on years of inspection and testing, it has been observed that in three key physical property tests—airtightness test, hydrostatic test, and drop test—the difference between square and round curling barrels is not significant in the first two tests. However, during the drop test, the performance gap becomes clear. Square curling barrels tend to crack or leak more frequently than their round counterparts. Why does this happen? Let's explore the reasons from the perspective of crimping design.
When materials undergo deformation, internal stress is generated. This stress tends to concentrate at the deformed areas. If the material exceeds its yield limit, cracks can form. In the case of a round curl, the stress from deformation is evenly distributed around the entire bead, preventing stress concentration at any single point. On the other hand, in a square curl, the stress tends to accumulate along the curled ridge, making it more prone to failure under impact.
When a liquid-filled drum falls from a certain height, especially at a 45-degree angle, the square curling barrel is the first point of contact with the ground. The impact force causes deformation, and due to the high internal stress, the force may exceed the material’s allowable limit, leading to plate cracking. Even if the plate doesn’t break, the combined forces may cause the curl to deform significantly, potentially separating the layers and resulting in leakage. In contrast, a round curl distributes the external impact force evenly across the circumference. This reduces the likelihood of exceeding the material’s stress limit, keeps the curl deformation minimal, and maintains the compact structure of the rolled edge. As a result, round curls are less likely to crack or open.
Based on long-term inspections of most steel drum factories in Xinjiang, it has been found that when conducting drop tests according to national standards, round curling barrels perform better than square ones when dropped from a height of 1.2 meters. Manufacturers often refer to round curling barrels as having a higher safety factor. From the perspective of real-world loading and unloading conditions, after filling with liquid, round curling barrels demonstrate superior impact resistance and can withstand harsh handling. In comparison, square curling barrels are less adaptable to such conditions.
Of course, from a production standpoint, manufacturing round curling barrels requires more precise tooling and skilled operation. The burring wheel, which is a consumable part, demands careful handling. If the technique is not well mastered, issues can arise, which is why some manufacturers still prefer square curls. Despite this, the structural advantages of round curls make them a preferred choice for applications where safety and durability are critical.
Square Curl
Round Curl
Briefcase,Leather Briefcase,Briefcase For Men,Brief Case
Ningbo Fineweather International Trade Co., Ltd. , https://www.fwsbag.com