Factory is a very important facility in a city. Factories produce materials for the construction of cities and sometimes ship them to other cities or export them. There are many different types of factories, some making building materials, some making daily necessities, and even some processing food. This week we focused on factories that deal with building materials and learned how the assembly lines that make steel pipes work. Photo of a Factory After the observation of the production line and interview with the workers, we got to know the production process of the steel pipe. Firstly, they transport this kind of rolls of steel from a steel mill in Shanghai. A Roll of Steel Then the steel plate is then squeezed by rolls of different sizes to bend into a round tube as it moves through the tracks. Shaping Tool Next, the steel pipe being bent into a round tube passes through an electric welding shop, where the edges of the steel plates are welded together. Electric Welding Shop After be...