A dynamic programming solution to automate fabrication sequencing of industrial construction components

Increasing complexity of petro-chemical projects, fast-tracked engineering, and tighter schedules pose a challenge for pipe spool fabrication shops. To maintain competitiveness, it is necessary to improve the shop performance, i.e. fabrication cycle time. Pipe spool fabrication sequence is found to have significant impact on cycle time and presents an area with potential for improvement. Traditionally, fabrication sequences are determined by shop foremen in a heuristic manner and optimality is not guaranteed. This paper presents a dynamic programming (DP) algorithm to automatically identify the optimal fabrication sequences for pipe spools. Simulation experiments are conducted to test the effectiveness of the algorithm by comparing the cycle times resulting from the algorithm-generated sequences and human-planner-designed sequences, respectively. The results show that the DP algorithm reduces unnecessary position-welding (9 out of 20 position-welds) and results in a reduction in the total fabrication cycle time by a range of 4.8% to 12%.