Acoustic Emission technology has for a number of years been used to monitor the active corrosion condition of Above Ground Storage Tanks floors.
This technique provides a non-intrusive method of determining the active corrosion condition of tank floors without the need to open, clean and inspect. Costs involved in cleaning and inspecting a tank floor can be very high, and if the floor after inspection proves to be in a good condition, then the time and cost could have been better used elsewhere.
How it Works:
The tank under test must be isolated for 6 to 24 hours depending on tank size and contents, with all valves closed, with all heaters and agitators switched off. The Acoustic Emission sensors are mounted in array around the tank shell, usually in one or two rows with the bottom row carrying out the monitoring function and the upper row filtering out noise sources from shell and roof. The acoustic activity in the tank is then monitored and stored. Acoustic activity is produced by the fracture of corrosion products under head of product and sources (higher energy) that can be potential leak sites/indications.
• To avoid taking the tanks with good conditions out of service which will save the cost of down time and maintenance activities.
• To prioritize and plan effectively for which tanks to be taken out of service based on the inspection results and tank conditions.
• Only tanks with poor conditions will be taken out of service.
• Inspection cost can be neglected if compared with taking the tank out of service, cleaning, scaffolding….etc.
• Inspection takes very short time.