## 4 Data Analyses, Discussion and Findings
### Pattern and Route
The production process includes cutting, threading, leveling, welding (for example, the flange need to be weld to a corresponding pipe), conveyor handling, pre-assembly, labeling, and packaging. As shown in Figure 9, the basic configuration of the pipe fabrication production line consists of one set of fixed-type high-speed pipe cutting machine, one sets of fixed-type pipe end beveling machine, many sets of the piping prefabrication fast fitting-up machine, many sets of piping automatic welding machine, and a set of the automatic conveying system. Besides, in some projects, the pipe coating machine is needed to distinguish different piping systems. The management process ranges from communication with BIM group, procurement planning, production planning and control, transportation, and coordination with the site. Some information technologies based on BIM should be developed to improve the efficiency of prefabrication. For example, after the detail design of prefabricated components, explicit information (e.g., system name, size, ID) and implicit information (the location of the pipe, the connected fittings) can be marked in the drawing. The size of pipes that planned to be prefabricated in the facility can be exported from BIM software to the central database, then be imported into the computer numerical control (CNC) machine. Moreover, some information  
Figure 8: Prefabricated pipes marked with information exported from BIM model. in the BIM model can be used for procurement. In the production process, the quick response (QR) code can be labeled on the pipe. Then the QR code is used to search the information in the BIM model automatically. The fourth phase is an improvement and expansion of the third phase. The contractors can attempt to fabricate and assemble larger and more complex components (standard and nonstandard) such as pump sets and prefabricated packaged pump rooms. Take the pump room for an example, although the result of the survey indicates that the prefabrication of pipes in pump rooms is highly feasible, the successful implementation of piping prefabrication in pump rooms need to expand another production line. The pump room is characterized by a variety of different types of system, fittings, and valves, crosswise of horizontal and vertical pipes, and large-scale equipment. These characteristics increase the complexity and challenge for prefabrication. A number of components of special-shape in the pump room need to be prefabricated. The detailed design and pipe splitting of the pump room consume more time than a single system as the pipes are set closer. The location of large-scale equipment has a significant effect on the pipes layout and the prefabrication solution. Therefore, the production line used to produce standard components is not applicable for these nonstandard components. If the facility is expanded, higher productivity and applicability can be obtained in this phase. The simpler the prefabricated components, the more interfaces between the components. If the complex component is prefabricated in the facility, there will be few construction activities on site. This results in higher efficiency and less working space requirement on site.