Effects of Sa 2 and Sa 2.5 Blast Cleaning Surface Preparation on the Adhesion and Corrosion Protection Properties of Coating

• Main Author: Amirrudin, Muhammad Munzir
• Format: Final Year Project
• Language: English
• Published: Universiti Teknologi PETRONAS 2011
• Subjects: TJ Mechanical engineering and machinery
• Online Access: http://utpedia.utp.edu.my/10443/1/2011%20-%20Effects%20of%20SA%202%20and%20SA%202.5%20Blast%20Cleaning%20Surface%20Preparation%20on%20the%20Adhesion%20and%20Corrosio.pdf; http://utpedia.utp.edu.my/10443/

Corrosion is a major problem for oil and gas operators as the cost consumed each year in fighting corrosion are staggeringly high. Along with the implementation of cost-effective corrosion prevention methods, the race for reducing cost consumption still goes on. Protective coating is considered to be one of the most economical methods there is. However, in the application of protective coating, the cost allocated for surface preparation exceeds the coating material costs itself by 21 %. The typical standards currently used by PETRONAS required the steel substrates to be blast cleaned to the ISO cleanliness standard of Sa 2.5. Thus this project aims for the practice of a cheaper alternative of cleanliness standards which is Sa 2. Three samples (carbon steel) are blast-cleaned to the standard of Sa 2.5 and three others to the standards of Sa 2. All samples are coated based on coating system No. lA in PTS. Corrosion test (ASTM B117-90) and adhesion test (scratch test) are conducted exclusively to measure the performance of coating system under different surface cleanliness standards. Four samples (two samples with Sa 2 and others with Sa 2.5 cleanliness standards) had undergone corrosion test. Remaining two samples, each with Sa 2 and Sa 2.5 cleanliness respectively, had undergone adhesion test. Calculation on corrosion rate using mass loss method and visual examination for evaluating the rust grade are done to determine the corrosion properties. Inspection using 3D non-contact measurement is conducted to confrrm the critical load experienced by the coating thus demrmining the adhesion properties. Findings for corrosion test shows a equal performance of coating between samples prepared under Sa 2 and Sa 2.5 cleanliness standards - corrosion rate of 0 millimeter per year and a rust grade of 10. Findings for adhesion test shows the critical load experienced by sample prepared under Sa 2 is 51N and higher than the sample prepared under Sa 2.5 which is 43N. However, acoustic emission shows a higher intensity profile from the sample prepared under Sa 2 standards compared to the sample prepared under Sa 2.5. Thus, for the success implementation of surface cleanliness of Sa 2, the performance of the chosen coating system are to result in similar or better performance in comparison to the application of Sa 2.5.