Explains the use of the process chart and assembly process chart in the study of a transformation process involving complex flow of products and subassemblies. Process chart is a powerful tool having applications in method improvement programme, layout of plant facilities, etc. By recording the flow of materials, products, etc, it helps in the elimination of avoidable delays and movements, combination/elimination of operations, and development of the most desirable arrangement of facilities. In the example, such a chart is to be used for the study of a process for manufacturing valves.