How to calculate life cycle cost (LCC)?
LCC = initial cost + maintenance cost + failure cost - residual value. The initial cost of duplex steel for submarine pipelines is 40% higher than that of carbon steel + coating, but 50% of maintenance costs can be saved in a 30-year cycle. The discount rate value significantly affects the results (such as 3% for nuclear power and 8% for chemical industry).
What is the impact of alloy element price fluctuations on costs?
For every $1/pound increase in molybdenum prices, the cost of P91 steel pipes increases by $80/ton; the surge in nickel prices in 2022 caused the price of Inconel 625 pipes to double. Futures hedging is the mainstream response strategy, and large factories usually reserve 3-6 months of consumption.
What is the economic boundary of thin-wall design?
A 1mm reduction in wall thickness can save 8% in material costs, but requires a 20% increase in NDT testing costs. ASME B31.3 stipulates that the minimum wall thickness = tₘᵢₙ = tₙₒₘ × (1-12.5% tolerance) - corrosion allowance. Calculations for a certain project show that the total cost of a 6mm wall thickness is 15% lower than that of an 8mm solution.
Cost-effectiveness of using recycled materials?
Using 30% scrap steel in electric arc furnace smelting can reduce energy consumption by 60kWh/t, but the refining time is extended by 25 minutes. The proportion of scrap steel in 409L stainless steel used in automobile exhaust pipes can reach 80%, but recycled materials are prohibited for nuclear power pipes.
Hidden costs of local procurement?
The tariff on imported alloy pipes is about 5-8%, but insufficient batches of local suppliers may extend the delivery time by 2 months. Calculations for a petrochemical project show that the total cost of purchasing P92 pipes in Europe is 18% higher than that in China, but it saves 4 weeks of construction time.
