Our chemical selection and management service continues to save clients millions of dollars in preventing over injection, improving corrosion control and maximising flow assurance.
OUR CLIENT’s CHALLENGES
Recently, a chemical supplier has been unable to maintain normal Corrosion Inhibitor (CI) supply to one of our clients. The global CI shortage has been a known issue for circa 12 months.
Figure 1: Timeline of events during the CI shortage
HOW WERE THE CHALLENGES ADDRESSED?
A temporary corrosion inhibitor injection strategy was put in place to minimise internal corrosion risk throughout the process trains whilst issues with the chemical stock persisted. The strategy focused on limiting internal corrosion in systems where the most severe unmitigated corrosion was expected to occur. However, there would be an inherent increase in the overall risk to the system until the CI supply issues were resolved and the original inhibitor targets were reinstated. It was vital to carefully monitor the effectiveness of the inhibitor to ensure that it provided adequate protection during this temporary period.
To manage the increased risk caused by the corrosion inhibitor supply issues and look for opportunities for potential dose rate optimisation, a critical review of CI dose rate requirements was carried out along with inhibitor lab testing from December to January.
WHAT WERE THE OUTCOMES?
Below are two graphs representing corrosion inhibitor performance for the month of December and the varying performance over the past 6 months.
From the graphs, we can deduce that there are significant dips in the trend resulting from underdosing where the set target was not satisfied. On occasions, these dips could have also been due to power issues causing the skids to be switched off, generator maintenance activities or the CI pumps not being calibrated on days the injection rates were taken.
Figure 2: Corrosion inhibitor performance for December (left) and the last 6 months (right)
OPTIMISING THE USE OF CORROSION INHIBITORS
There are several approaches that can be used to optimise the use of chemicals for corrosion inhibition:
Selection of appropriate inhibitors: It is important to choose corrosion inhibitors that are effective in the specific corrosive environment found. This may involve testing different types of inhibitors, such as organic compounds, inorganic compounds or inhibitor blends to determine their effectiveness.
Adjustment of inhibitor concentration: The concentration of the corrosion inhibitor can have a significant impact on its effectiveness. It may be necessary to adjust the concentration of the inhibitor to find the optimal level for corrosion control.
pH and temperature control: The pH and temperature of the process stream can also influence the effectiveness of corrosion inhibitors. It may be necessary to carefully monitor, and if possible, adjust the pH and temperature of the process stream to optimise corrosion control.
Continuous monitoring and evaluation: It is important to continuously monitor and evaluate the performance of the corrosion inhibitors to ensure that they are providing adequate protection and to make any necessary adjustments.
Secure alternative sources of supply: It is critical that any known or suspected supply chain vulnerabilities are actively managed between engineering and procurement teams to ensure that multiple sources of supply are maintained. Contractual arrangements with alternative suppliers should be in place, and in instances where a single supplier is the only possible option, this must be mitigated through a formal risk assessment.
Use of corrosion modelling software: Corrosion modelling software can be used to predict the corrosion rates and the effectiveness of corrosion inhibitors under different conditions. This can help to optimise the use of corrosion inhibitors and to develop more effective corrosion control strategies.
With our client, a CI testing protocol has been adopted, and is currently being implemented. Such a strategy will provide the operator with multiple CI options, and alternative strategies, that will play the same if not a better role in the chemical management process.
CORROSION CONSULTANCY SERVICES
AIE provides service capabilities and expertise to operators. From initial desktop reviews right through to development of action plans and long-term monitoring programs with KPIs, AIE takes a holistic approach to the topic of corrosion inhibition.
VeracityCCM software can accommodate all CI relevant data and perform data correlations to facilitate conclusions and recommendations. Learn more about veracity here.
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