Acoustic Emission Testing for Vessels & Tanks Monitoring

a.SAEU3H Acoustic Emission Detection System

c.Data Acquisition System Specs

SWAE acoustic emission system software is a combination of real-time acquisition and analysis and post-analysis software. It supports two types of AE product series, SAEU3H instrument and RAEM1 series (RAEM1 and RAEM1-6) respectively. SWAE can perform data acquisition, playback and analysis on the equipment. Its main functions are location map, correlation graphs, data table, and frequency domain waveform map, etc.

According to Section 9.2 of the standard “JB/T 10764-2023”, the time difference location analysis and classification methods of the tank bottom acoustic emission source were adopted. The length of 10% of the diameter was used to delineate a circular assessment area. Perform local analysis on all location sources with relatively concentrated events within the evaluation area and calculate the number of location events E per hour. According to Figure 1.5, three were 173 effective events during pressure maintenance and there were 3 relatively concentrated locating areas, defined as S1, S2, and S3.

S1: E1=7; S2: E2=10; S3: E3=4.

The reference event number per hour criterion was set as a=10, based on experiences results using the same testing equipment and settings under the same environment.

Considering the liquid level height during pressure maintenance and the comprehensive acoustic emission characteristic parameters, the classification result was Level I, which means “there are no signs of local corrosion, and the corrosion condition is minimal”. The repairing suggestion: do not consider repair. It is recommended to conduct acoustic emission testing again within 6 years or open the tank at an appropriate time to observe the dynamic changes of corrosion on the tank bottom plate.

Qingcheng Cloud Platform is our own developed cloud platform for all our IoT products. The QC Cloud Platform can achieve data display and analysis, configuration, alarms, data downloading and reports.

a. Cloud platform data display: real-time/historical (parameter/waveform) data, rating results, correlation graphs etc.

c. Automatic alarm notifications: Alarm messages are sent to the clients through SMS/emails.

d. Automatic report generation After filling in relevant information through the cloud platform, the system automatically generates a report. And download the report from the cloud platform with one clicking.

1)Case 1: AE Detection of Storage Tanks at Xingsan Joint Station

The storage tank had a volume of 5000 cubic meters, a diameter of 22.7 meters, and an effective height of 16.14 meters. It stored crude oil. The tank walls were coated with anti-corrosion paint and insulated with composite aluminum-magnesium silicate felt and sheet metal protective plates.

Acoustic emission sensor arrangement: Nine sensors were evenly distributed around the outer wall approximately 50 centimeters above the bottom plate, avoiding structural discontinuities such as pipes and manholes, with a horizontal spacing of approximately 7.8 meters.

Data acquisition and analysis: Conducted acoustic emission testing on the storage tank for 2 hours.

2)Case 2: Weld Propagation Detection in Main Absorption Tower

The storage tank had a volume of 5000 cubic meters, a diameter of 22.7 meters, and an effective height of 16.14 meters. It stored crude oil. The tank walls were coated with anti-corrosion paint and insulated with composite aluminum-magnesium silicate felt and sheet metal protective plates.

Acoustic emission sensor arrangement: Nine sensors were evenly distributed around the outer wall approximately 50 centimeters above the bottom plate, avoiding structural discontinuities such as pipes and manholes, with a horizontal spacing of approximately 7.8 meters.

From January 4th to 6th, 2023, experimental data collection and analysis were conducted on the C-101C tower throughout its entire production cycle, aiming to explore an effective, accurate, and feasible online monitoring method for alternating fatigue vessels. The on-site 12V lithium battery provided power for approximately 34 hours. Signal acquisition for the entire coking tower production cycle was completed from 15:00 on January 4th to 1:00 on January 6th, 2023.

Sensor Installation: Monitoring focused primarily on the first and second main welds of the tower body. Waveguide rods were used for auxiliary sensor installation. The waveguide rod length was determined by ensuring the temperature at the non-welded end of the waveguide rod dropped below 60℃. The minimum waveguide rod length was greater than the insulation layer thickness. Waveguide rods could be installed using welding or high-temperature adhesive bonding.

The storage tank was an external arch roof tank with a capacity of 10000 cubic meters, a diameter of 27.75 meters, an effective height of 14.8 meters, and a storage medium of crude oil. The safe liquid level was 12.5 meters, and the initial liquid level detected was 17.8 meters. The tank wall was coated with anti-corrosion paint and had insulation boards and metal sheet metal protective plates.

ensors (probes) receive these acoustic emission signals, analyze their frequency, amplitude, energy, arrival time, and other characteristics to determine the generation and propagation of defects (cracks, pitting, corrosion).

AE is suitable for metal storage tanks (carbon steel, stainless steel, aluminum alloy) and some composite material storage tanks.

Yes, AE is very suitable for in-service tanks online monitoring. Because AE is one of the non-destructive methods. By installing AE sensors on the external wall surface of the tanks and the AE monitoring system units, it can monitor the active corrosion or cracking of the tanks in real-time without stopping services, or without opening and cleaning the tanks.

Yes, AE can detect early-stage initial cracks. But the location accuracy is affected by the sensor spacing and the material.

Acoustic ultrasound (AE) can determine the state and severity of defect propagation, and can estimate life by combining it with other methods (such as ultrasound testing - UT), but direct quantification is complex.

It depends on the tank size. A row of sensors is placed on the tank wall near to the tank floor, and it shall be ensured that they are above the height of the sediment in the tank. Thick layers of sediment affect the sensitivity of AE.

If there are manholes, nozzles and welded structures between two adjacent sensors, the maximum spacing shall not exceed 13 m. We recommend the sensor spacing doesn’t exceed 11m. But it is highly suggested to do the attenuation test on site to confirm the attenuation distance and then to decide the final sensor spacing.