The following case study for a walkway in Chile demonstrates how the App can be used to answer the three competition questions
CASE STUDY: A walkway in a copper plant in Chile in 2007.
Two stainless steels (a utility ferritic, such as 3CR12 and a lean duplex, such as LDX 2101) were compared with mild steel. It was assumed that the utility ferritic and the mild steel would have the same gauge due to similar strength levels, however, the higher strength of the lean duplex allowed for down gauging by 25%.
Material costs used were actual Chilean domestic market costs at the time. The fabrication costs were calculated by a leading Chilean fabricator. The operating costs for mild steel were calculated as a painting cost every four years and a replacement every eight years. For stainless steel, there was only a high pressure wash every 15 years and end of life recovery of the scrap, resulting in negative operating costs for both stainless steels. The design life was 30 years with a cost of capital of 8.5% and an inflation rate of 6.8%.
From the table below, it can be seen that the initial cost of the utility ferritic walkway was about double that of the mild steel walkway and the lean duplexFrom the table below, it can be seen that the initial cost of the utility ferritic walkway was about double that of the mild steel walkway and the lean duplex.
QUESTION 1:
Calculate and compare what the costs would be to build the walkway in mild steel and either utility ferritic stainless steel or lean duplex stainless steel.
Mild Steel: $880 949
Utility Steel: $1 747 680, or
Lean Duplex: $2 721 361
QUESTION 2:
Calculate and compare what the operating costs would be for the walkway for 30 years if it were built in mild steel and either utility ferritic stainless steel or lean duplex stainless steel.
Mild Steel: $2 309 559
Utility Steel: -$149 001, or
Lean Duplex: -$248 905
QUESTION 3:
Calculate the total life cycle costs of the walkway in mild steel and either utility ferritic stainless steel or lean duplex stainless steel.
Mild Steel: $3 190 508
Utility Steel: $1 598 679, or
Lean Duplex: $2 472 456