How in the absence of figures, can we justify the economic loss due to microbial corrosion? Proposing 'Deductive Estimation Approach' as a rough Estimation

摘要

If corrosion is affected by the presence and action of microorganism such as, but not limited to, bacteria it is called microbiologically influenced corrosion (MIC) or alternatively, microbial corrosion. Almost all engineering materials (except Titanium alloys) are vulnerable to MIC. Some examples of industries vulnerable to MIC are as follows: 1. Pipelines (on-shore/offshore- water & waste water treatment... 2. Chemical processes equipment (HX, condensers, ...) 3. Hydrants (fire water) rings Water and waste water treatment plants 4. Thermal/combined cycle powerplants Risk of MIC increases if 1. If the water used in the system (either as process water or cooling water) is on liquid form, undertreated or maltreated, is stagnant (flow rate less than 1.5 nVs),and is in contact with rough surfaces (eg after welding). Based on existing knowledge about the economic impact of corrosion and MIC, it has been established that the cost of corrosion to the economy of countries is between 3-5 % of their GDP (Gross Domestic Product). While fluctuations in this range is also acceptable, the norm can be taken as such. On the other hand, the minimum economic loss due to MIC is about 20% of the total loss due to corrosion. Even this figure is not constant so that in some industries the economic contribution of MIC can even reach to 50% of the corrosion loss. While these numbers are results of some sporadic researches, there is no numbers that show clearly shows the ranking of MIC among the economical loss due to other corrosion processes. However due to many factors, for many countries no official tracks about the economic impact of MIC is available. Therefore, we will use a method that we call as "Deductive Estimation Approach" or DEA for short. DEA is based on the following four basic assumptions: 1. Share of economic loss due to corrosion in any given country is minimum 3% and maximum 5 %. We will take this share as to be 3% of the GDP of that country. 2. Share of economic loss due to MIC will be taken as 20% of the loss due to corrosion in any given country. 3. Economical loss due to MIC in any given industry in a any given country will be calculated based on the share of that particular industry in that particular country's economy 4. Economic loss due to MIC in that country is calculated by then taking 20% of the resulting figure for the economic loss due to corrosion in that country. In this paper after describing the EDA method, its pros and cons are discussed in details. It must be noted that for many countries-especially oil producing countries- it is not possible to have such figures as issued from official entities. Therefore, having a rough estimation method that can give an idea about the economic loss due to MIC is an opportunity to be appreciated by many organizations/companies where MIC could be a significant source of problems.