Our plant produces Metallurgical coke with an installed capacity of 1.6 MT/ annum. Wet type coke quenching process is adopted, and water used for the quenching process has chloride level of 4900ppm(maximum). Severe corrosion is experienced at the coke Quenching car and the steel structures of Coke conveyor gallery adjacent to the quenching tower, which is exposed to the coke quenching water vapour. Replacement of steel structures are carried out at regular interval and the approximate expenditure is Rs. 2.0 Cr./annum. Painting of conveyor and other structures is a regular activity which is carried out throughout the year except for the monsoon months. The annual expenditures incurred pent is in the tune of Rs. 2.5 Cr.
The major challenges encountered are listed below:
1. The level of corrosion is very high, which requires regular painting and replacement of steel structures.
2. The paint life is very less and execution of the job at running equipments is very hazardous.
3. The structural replacement methodology is not clear in all cases and requires extensive planning.
Options tried to solve before:
Different painting schemes have been tried out and finally application of Epoxy primer as base coat, high build micaceous iron oxide (MIO) along with Polyurethane finish paint has been adopted. This is also giving a maximum life of one year.
The solution MUST fulfill the following requirements:
1. We want a suitable painting method with suitable paint to get better paint life.
2. A suitable grade of steel material for this application which can be used in such a corrosive atmosphere.
3. Paint life of minimum two years or more.
4. Application of better quality steel for strengthening the Quenching car and other structures.