Corrosion economic costs

Corrosion Control control of the corrosion rate and form of attack of a metal of a given metal/environment system at an acceptable level and at an economic cost. 

PLATE 8 Corrosion is a chemical process whose results are easy to see in the world around us. In this picture, corrosion of reinforcing steel has caused the conerete pillars to spall, weakening the bridge and forcing the installation of wooden joists to temporarily support the bridge deck structure. The results of corrosion impose significant economic costs on society—in 1982, these eosts were estimated at about 120 billion. Courtesy, Robert Baboian, Texas Instruments, Inc. 

In the most recent official assessment of the economic costs of equipment damage arising from corrosion, prepared by the National Commission on Materials Policy (U.S.), il was staled that annual losses in the Uniicd Stales alone are on the order or many billions of dollars. 

Corrosion economics and corrosion management forms the theme of the fifth chapter. Discounted cash flow calculations, depreciation, the declining balance method, double declining method, modified accelerated cost recovery system and present worth calculation procedures are given, together with examples. In the second part, corrosion management, including the people factor in corrosion failure is briefly presented. Some of the expert systems presently available in the literature are briefly discussed. 

The economic cost of corrosion in the United States has been estimated (1) to be about 120 billion (in 1982). This staggering figure amounts to about 4 percent of the gross national product, or more than 500 per person annually in the United States. The broad... 

Finally, it is noted that much interest is concentrated on the development of intermetallic alloys for use as blades in flying gas turbines. This application is most demanding and it is not clear whether all the problems with strength, ductility, toughness, and corrosion resistance can be solved at economic costs. Less-high-technology applications may be more reward-... 

Economic costs involved in rectifying the corrosion damage. 

The first category can be dealt with by straightforward reference to the economic costs of repair, although the actual calculation is by no means straightforward as dose/response relationships depend upon the depth of corrosion that has taken place, climate, local building materials, construction methods, etc. Nevertheless attempts to estimate building damage costs have been made. 

Polyester resins are widely used due to their versatility and economic cost. Polyester exhibits a good combination of resistance to softening and deformation at elevated temperatures, good electrical properties and high resistance to corrosion as well as excellent weatherability [30, 31]. Structural applications, such as reinforced polyester containing glass fibre, comprise more than 80% of the market. Table 2.6 illustrates some of the physical parameters of polyester. 

Steel is so versatile that it is used in all industries, but it is particularly vulnerable to corrosion. The wide range of uses has greatly extended, at an economical cost, the use of zinc to prevent corrosion. 

Any clean solid surface is actually an active center for adsorption from the surroundings, for example, air or liquid. In fact, a clean solid surface can only exist under vacuum. A perfectly cleaned metal surface, when exposed to air, will adsorb a single layer of oxygen or nitrogen (or water) (degree of adsorption will, of course, depend on the system). The most common example of much importance is the process of corrosion (an extensive economic cost) of iron when exposed to air. Or when a completely dry glass surface is exposed to air (with some moisture), the surface will adsorb a monolayer of water. In other words, the solid surface is not as inert as it may seem to the naked eye. 

The science of corrosion has had twoperiodsof rapid advancement One, in the first half of the nineteenth century, was a result of intense and sustained scientific interest and activity aroused by the invention of the galvanic battery, and the controversy over the nature and source of the galvanic current. The other, in the first half of the twentieth century, was stimulated by growing realization of the immense economic cost of corrosion in a rapidly developing industrial age. In the latter period, a number of theories and facts established in the earlier one were rediscovered or elaborated, or both. These include the electrochemical theory of corrosion, proposed by Wollaston in 1801, developed by de La Rive in 1830, confirmed by Ericson-Auren and Palmaer in 1901, and rediscovered by Whitney in 1903 [2]. 

During the first quarter of the 20th century, the full economic cost of the corrosion of metals was perceived. The first reported corrosion experiments on aluminium started around 1890, when the metal was available in a quantity sufficient to envision its use for construction and as kitchen utensils. Its resistance to rainwater and various types of drinks, such as beer, coffee, and tea, was first assessed at the beginning of the 1890s [4]. 

In a like manner, the refractory technologist considers a particular refractory application he, like his customer, desires a long, lasting refractory life at an economical cost to the consumer. The technologist contemplates the overall environmental and wearing mechanisms to which the refractory will be exposed including temperatures, gas pressures, chemically corrosive agents and/or... 

Because an excess of ammonia is fed to the reactor, and because the reactions ate reversible, ammonia and carbon dioxide exit the reactor along with the carbamate and urea. Several process variations have been developed to deal with the efficiency of the conversion and with serious corrosion problems. The three main types of ammonia handling ate once through, partial recycle, and total recycle. Urea plants having capacity up to 1800 t/d ate available. Most advances have dealt with reduction of energy requirements in the total recycle process. The economics of urea production ate most strongly influenced by the cost of the taw material ammonia. When the ammonia cost is representative of production cost in a new plant it can amount to more than 50% of urea cost. 

The processiag costs associated with separation and corrosion are stiU significant ia the low pressure process for the process to be economical, the efficiency of recovery and recycle of the rhodium must be very high. Consequently, researchers have continued to seek new ways to faciUtate the separation and confine the corrosion. Extensive research was done with rhodium phosphine complexes bonded to soHd supports, but the resulting catalysts were not sufficiently stable, as rhodium was leached iato the product solution (27,28). A mote successful solution to the engineering problem resulted from the apphcation of a two-phase Hquid-Hquid process (29). The catalyst is synthesized with polar -SO Na groups on the phenyl rings of the triphenylphosphine. 

Corrosivity. Corrosivity is an important factor in the economics of distillation. Corrosion rates increase rapidly with temperature, and in distillation the separation is made at boiling temperatures. The boiling temperatures may require distillation equipment of expensive materials of constmction however, some of these corrosion-resistant materials are difficult to fabricate. For some materials, eg, ceramics (qv), random packings may be specified, and this has been a classical appHcation of packings for highly corrosive services. On the other hand, the extensive surface areas of metal packings may make these more susceptible to corrosion than plates. Again, cost may be the final arbiter (see Corrosion and corrosion control). 

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