There are typically three methods for on-site loading of second-hand container cargo: manual loading, where forklifts (trucks) are used to move items into the container, followed by manual stacking; and full mechanical loading, such as using forklifts to stack palletized cargo inside the container.

1. In any case, the weight of the goods inside the container must not exceed the container's carrying capacity, which is the total weight of the container minus its own weight. Generally, both the total weight and the tare weight are marked on the container's door.

2. Each container has a fixed unit weight capacity. Therefore, when loading the same type of goods inside the container, knowing the density of the goods allows us to determine whether it is heavy or light cargo. Cheng Qiwei stated that if the density of the goods is greater than the container's unit weight, it is considered heavy cargo; otherwise, it is light cargo. Promptly and clearly distinguishing between these two different scenarios is crucial for improving loading efficiency.

Ensure that the load on the bottom of the box is balanced during loading, and especially strictly prohibit the situation where the load center is skewed to one end.

4. Avoid concentrating loads. "For instance, when loading heavy items like machinery, the bottom of the container should be lined with wood or other cushioning materials to distribute the load as evenly as possible. The average load per unit area on the bottom of a standard container is approximately: 20-foot container - 1330x9.8N/m, 40-foot container - 980x9.8N/m².

5. When loading goods manually, pay attention to any handling instructions on the packaging, such as "Do Not Tip," "Flat," or "Upright." Always use the proper loading tools, and do not use hand hooks to bundle packages. The goods inside the box should be loaded neatly and packed tightly. For goods that are prone to unpacking or have fragile packaging, use padding or insert plywood between the goods to prevent movement within the box.

6. When loading palletized cargo, it is crucial to accurately measure the internal dimensions of the container and the external dimensions of the cargo packaging to calculate the number of pieces loaded, in order to minimize wasted space and maximize cargo capacity.

When loading with forklift trucks, the lifting height of the machinery and the height of the door frame impose constraints. Therefore, under permissible conditions, forklift loading can handle two layers at once, but there should be a certain gap between them. If it's not possible to load two layers at once, when loading the second layer, consider the lifting height of the forklift truck and the potential lifting height of the door frame. At this point, the door frame's lifting height should be the height of one layer of goods minus the lifting height, allowing the second layer of goods to be placed above the third layer.

Additionally, the standard forklift with a lifting capacity of 2 tons typically has a lifting height of around 1250px. However, there is also a full-lift height forklift, which, as long as the interior height permits, is not affected by the gantry lifting height and can easily stack two layers of goods. Moreover, it is important to note that wooden blocks should be placed beneath the goods to facilitate the smooth withdrawal of the forks.

Goods should not be directly packed; at least, some form of packaging is required. Do not solely prioritize saving space at the expense of damaging the goods. Most goods do come with packaging, but larger items like boilers and construction materials can be more challenging, requiring tying and securing to prevent loosening. In reality, with careful attention, major issues can be avoided.