Acoustic Emission to Tank Storage bottom Inspection

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1 HYBRID PETROLEUM INSTITUTE S. DE R.L. DE C.V. Acoustic Emission to Tank Storage bottom Inspection

2 About method Acoustic Emission is the process of detection of the sound produced by discontinuities in the bottom plate when the storage tank is leaking or corrosion. Sensors position The sensors are usually mounted 1 m and 2 m above the body Number of sensors recommended according to tank diameter: Less than 25 meters 6 sensors From 25 to 30 meters 9 sensors From 30 to 50 meters 12 sensors From 50 to 62.5 meters 16 sensors From 62.5 to 75 meters 18 sensors From 75 to 87.5 meters 21 sensors From 87.5 to 100 meters 24 sensors The sensor cables are activated at the AE computer Guard Sensor Primary Sensor Sensitivity of the method: detects noise discontinuities are even below 2 db. Temperature range which can be used: only depends on the temperature that sensor endure. Type of tanks where it is possible Acoustic Emission: Single wall, double wall, fixed dome, floating roof. You can inspect all types of storage tanks, with their considerations: Double wall storage tanks: Fixed dome tanks: one internal sensor (intrinsically safe) shall be suspended by the top of the tank in order to discriminate the emissions coming from the bottom of the tank floor. Floating roof tanks: it is recommend using a second row of sensors se recomienda usar una segunda fila de sensores. The way to place the sensors in the second row must be identical to the major and mounted three meters above the main row of sensors.

3 Acoustic Emission to Tank Storage bottom Inspection Normativity ASTM: E 569 Acoustic Emission Monitoring of Structures During Controlled Stimulation E 650 Guide for Mounting Piezoelectric Acoustic Emission Sensors E 750 Practice for Characterizing Acoustic Emission Instrumentation API: RP 575 Guidelines and Methods for Inspection of Existing Atmospheric and Low- Pressure Storage Tank. ST 307 An Engineering Assessment of Acoustic Methods of Leak detection in Aboveground Storage tanks. ST 322 An Engineering Evaluation of Acoustic Methods of Leak Detection in Aboveground storage Tank. ST 325 An evaluation of a Methodology for the detection of Leaks in Aboveground Storage Tank. What detects? Grietas Existentes. Plastic deformation of the material. Corrosion process, when active. Damage caused by corrosion. Leak. Conditions of repose of the stored fluids: Storage tanks to be examined must be at least 50% capacity and preferably at 90%. Product Heavy (raw) Ligth (light naphtha or gasoline) Resting time 24 hour 12 hours Blocking conditions: The tank should be isolated: The inlet and outlet nozzle of product must be sealed to prevent noise The equipment that are in the periphery such as pumps, mixers and heaters should be turned off and there should be no sources of noise that could interfere such as: Vibration of adjacent pipes Leaking valves Relief valves operation Noisy activities adjacent tanks Individual components in the floating dome Individual components of the tank as pipes and ladders Hammering Level indicators or level bubble Leaking nitrogen damping systems Product inlet or dripping into the tank Current water that flow in tank roofs and strings or data plates loose on the wall of the tank

4 Reports: Graphics 2D, 3D/ graphics type plot plant of hits, events, clusters, energy, risk matrices

5 EVALUATION MATRIX FLOOR TANK MONITORING RECOMMENDATIONS Evaluación Diagnóstico Recomendaciones Implement operational controls immediately Evaluate maintenance options immediately AAI 5 Leak and / or damage significant Consider an internal inspection Open immediately and repair Re-inspect in 6 months or AAI 4 Highest corrosion, re-inspect in 6 months Evaluate maintenance options AAI 3 Corrosion, re-inspect maximum 1 year Re-inspect 1 year AAI 2 Minor corrosion, re-inspection in 2 years Re-inspect in 2 years AAI 1 No corrosion, re-inspection in 4-5 years Re-inspect in 4 years The thickness determination is indirect, since what is measured is the corrosion activity, allowing us to infer the remaining thickness. Because of this, the tank bottoms that have high probability of leakage are sent to reinspection 6 months or 1 year, while those who have little risk of leak is sent to reinspection to 2, 3 or 4 years. Using the equation: Risk = (Probability of corrosion or deterioration) x (consequense of leakage)

6 AE Testing Re-inspect periodically Detection and localization of damages by AE Classification of damages by AE Determine if the structure is currently undergoing an active damage and, if present, locate the source of damage and assess the severity. Assess the severity of damage using measures of activity and intensity. Monitoring? No Continue in service Characterization of defect type, size and orientation Sí Fracture mechanics, analysis of the critical size Use complementary PND's for the characterization of the source of AE. To determine the criticality of the defect shall use the actual load conditions with which the tank operates Yes Critical size? Repairs and maintenance No Fitness for Service (FFS) "Assessment of Structural Integrity Tank Bottom by Acoustic Emission" No FFS ok? Yes