Cost-effectiveness of stainless steel

	Abridged version

• The strong increase on the demand side and the increase inproduction have caused the price for the material to go down.
• A stainless steel construction in accordance with the advantages of the material characteristics decreases the weight and the price of the construction in question.
• Serial production following a standardisation reduces the unit costs as well as the production times.
• Specialization of certain processing plants producing stainless steel makes a rational production with specialized, stainless steel-suitable machines, plants and skilled mechanics possible.

Correctly processed corrosion-free stainless steel cannot be beat in its maintenance since no follow-up costs arise. The lifespan of stainless steel is measured in terms of the lifespan of the entire building. For this reason, use of stainless steel is sensible from the point of economics even when higher investment costs should accumulate. (siehe right diagram)

	High demands on the life of stainless steel

kind of plants	Ø period of use
examples of waste water treatment plants	50
sewer manhole	50 - 70
storm water building with overflow - constructional part	10 - 14
screen plant - mechanical part	12 - 20
secondary clarification tank - mechanical part	10 - 14
mechanical sludge dewatering	35
inlet penstock made of steel	40
water container, tabks	50
tank equipment	25 - 30
distributing pipes	40 - 60
dug-well	50 - 70

Table: average period of use for plants

	Example manhole equipment

cost example:			manhole equipment
equipment components:			manhole cover Ø800, with aeration, entrance aid, ladder,
			ventilation chimney, and sump cover
construction costs			12.000 EUR
equipment:			stainless steel 1.4301		normal steel, galvanized
investment costs			1.518 EUR		1.056 EUR
durability			50 years		25 years
investment for replacement afer 25 years.*			0 EUR		2.211 EUR
operation costs			0 EUR		0 EUR
maintenance costs			0 EUR/a		120 EUR/a
useful life			50 years		50 years
total costs			1.518 EUR		9.267 EUR
cost benefit adter				4.1 years in case of sainless steel
* taking into consideration an average cost increase
of 3% per year for investment for for replacement

With this comparison there will be a cost advantage for stainless steel already after a period of 4.1 years. To avoid malfunctioning of the structural parts due to natural corrosion damage the galvanised parts had to be replaced after about 25 years in this example. If stainless steel had been used for the initial equipment these re-investment expenses could have been saved today. Using the project-cost-cash-value method it is revealed that the equipment with galvanised steel becomes more and more expensive over the years. This example was calculated with a hypothetical price increase rate of 3%. Especially at the time of re-investment there is a sharp rise in the so-called cash value (see diagram).

diagram: project-cost-cash-value method