Abstract
M.Phil. (Engineering Management)
Corrosion is an undesirable electrochemical reaction that affects materials negatively. Electrons flow from a metal of high potential to a metal of low potential. Structures that are built with materials prone to corrosion can fail and lead to incidents, financial loss and reputational damage. Most of the major incidents and maintenance costs that occur in oil and gas industry are attributed to corrosion related failures. Globally; the direct cost of corrosion is estimated at $2.2 trillion per annum. Analysis of availability of tanks and pipelines in Company X shows that the available storage capacity is below 50% due to asset outages. Unavailability of assets are caused by breakdowns and extensive repairs attributed to corrosion related failures. The business disruption cost for 2016 only amounted to $1.1 million while the maintenance costs from 2013 to 2016 are estimated to $4.5mil.
Literature review reveals that corrosion is a problem in the oil and gas industry however it can be managed and controlled through design, installation of corrosion control techniques. Cathodic protection is effective in protecting buried and submerged structures while protective coating is effective for atmospheric corrosion. The case study used a mixed research approach, predominantly using quantitative data from the historical reports and qualitative research to gain clarity on the historical reports.
A gap analysis to determine the maturity of corrosion management is performed and the preliminary result showed that only one aspect of corrosion management is fully complied to. When the tanks are inspected, most of the measurements for wall thickness especially on the tank floor are below the design limits. Most of the tank breakdowns are caused by the failures on the higher tank shell courses. Some failures on the shell are picked up post inspection when the tank shell is being prepared for external protective coating. The corrosion rate picked on tank floors of the all the uncoated tanks and one coated tank in Mossel Bay is higher than the minimum expected rate on the carbon steel in the marine environment. Jet A1 tanks where the coating is applied with stringent quality controls had the lowest corrosion rate.
Inspectors prescribed repairs if wall losses are between 40 - 100% if the tank is to be operated for the next 10 years. Use of generic corrosion rate of 0.05mm per year gives inaccurate remaining life. The remaining life calculations using actual corrosion rates found that even the wall losses between 20 – 39% are not giving life beyond 10 years in Port Elizabeth in some tanks. The implication of the...