The appliance industry is one of the largest consumer product industries. For practical purposes, two categories of appliances are distinguished:
Major Home Appliances
Comfort Conditioning Appliances
In 1999, a total of 70.7 million major home appliances and a total of 49.5 million comfort conditioning appliances were sold in the United States, for a total of 120.2 million appliances. The average consumer buying an appliance is only marginally interested in corrosion issues and during the useful life of the appliance, no corrosion management is done by consumers. For example, very few people realize that there is an anode in every water heater, and that this sacrificial bar of metal should be checked and, if necessary, replaced with a new one, to prevent water heater failure due to internal corrosion. The life expectancy of appliances is determined from past experience and sales data. Improved corrosion design for appliances can increase their life expectancy. However, if improved corrosion protection would mean the use of more expensive components for the appliances, then consumers may not be interested. (reference)
A corrosion cost calculation was made for the sacrificial anodes in the 104 million water heaters in the United States. The benefits of anode maintenance are longer tank life, less rust buildup, and savings on costly changeovers. The increased life expectancy from anode maintenance can save money for consumers. However, a cost-benefit analysis may show that the cost of replacing anodes could exceed the benefits of increasing the life expectancy of water heaters. The annual cost of replacing water heaters was estimated at $460 million per year, the cost of anode replacement was estimated at $780 million per year, and a hypothetical design improvement that would increase the life expectancy of water heaters by 1 year was estimated to result in a savings of $778 million per year.
A corrosion cost calculation was also made for the annual coating costs of the 120.2 million newly purchased major appliances in the United States. Based on an estimated installed cost of coatings of $2 per appliance, the total cost is approximately $240 million per year. The cost of $2 is a marginal value in the average cost of appliances. Therefore, this cost is probably worth spending because of the more appealing appearance of non-corroding appliances. On the other hand, the internal components of appliances that are not directly visible to consumers should be protected from corrosion as well. For example, the above calculation does not consider the application of internal coatings, such as galvanizing steel, for a longer life.
The assumptions made in the anode calculations and the coating calculations are only approximations, and no adjustment is provided for the use of corrosion-resistant materials in most appliances. The calculations are probably not very accurate because of the great variety in appliances. Considering the great costs of appliances to consumers, and the fact that the potential savings from longer life expectancies can be considerable, it is recommended that a broad study, including a full analysis of statistical data, be performed to research the potential cost-savings related to increased life expectancies of appliances.
In summary, the cost of corrosion in home appliances is significant. The first cost is the purchase of replacement appliances because of premature failures due to corrosion. It is evident that water heater replacement is often attributed to corrosion. For water heaters alone, this cost was estimated at $460 million per year, using a low estimate of 5 percent of the replacements being corrosion-related. The cost of internal corrosion protection for all appliances includes the use of sacrificial anodes ($780 million per year), corrosion-resistant materials (no cost estimate), and internal coatings (no cost estimate). The cost of external corrosion protection using coatings was estimated at $260 million per year. Therefore, the estimated total annual cost of corrosion in home appliances is $1.5 billion per year ($460 million + $780 million + $260 million).