Question

Steel is used as a roofing material in a chemical refinery located in Darwin, Northern Territory. Estimate atmospheric corrosion rate of steel by employing the following approaches

ISO 9223

Bilogarithmic law

ISO CORRAG

Discuss the general trend of the results and, if any, the discrepancies among various methods.

Citation to scientific literature and any necessary sources for climatic conditions are encouraged

Answer 1

ISO 9223 and ISOCORRAG have the same approach:

This approach was designed by the ISO Technical Committee with the focus of systematizing environmental corrosion tests. The Programme started in the year 1986 and ISO 9223 was developed. These systems were established on an exhaustive analysis of environmental aspect programmes which took place in Europe and North America. The focus of constructing up these documents was to demonstrate easy and realistic recommendations for the technicians accountable for designing systems to be exposed to the environment and for corrosion engineers accountable for embracing anticorrosive protection methods. ISO 9223 gave a universal categorization system for environments built on measurements of atnospheric measures to predict time of wetness, amount of sulphur dioxide or deposition pace, and sodium chloride discharge pace.

In the ISOCORRAG Programme 14 countries took part in the subjection programme with a total of 53 manifestation sites. These areas included industrial, metropolitan, village, aquatic and coastal places in temperate and arctic areas. Horizontal carbon steel samples were revealed in threefold, fastening their dimensions and thickness in conforming with the allocation of standard. A set of samples was at the outset exposed for 1-year manifestation at each area. After six months, different set of samples was revealed for 1-year exposure. After 1 year, the first set of samples was detached and a different set of 1-year samples was exposed. Every 6 months, this operation was reiterated until 6 sets of samples were revealed for one year.

Results:

Exceedingly chilled areas, with yearly average temperatures less than 0^oC, have been exceedingly separated from the statistical investigation. That is the condition of the areas in Europe.Some of them are at Antarctic too. Very less temperatures need the metallic area to be coated with an ice layer for large periods in the year, significantly obstructing the improvement of corrosion procedure. This ice layer lessens oxygen entry to the metallic surface and its time of wetness, reducing corrosion pace to exceedingly low values.