Aboveground Storage Tank (AST) Bottom Plate Corrosion Detection/ Monitoring

System Composition:

Acoustic emission sensor, preamplifier, acoustic emission acquisition instrument, computer software.

Device Module	SAEU3H Multichannel AE detection system
Operation system	Windows
Channels	Multi-channels, cascadable to 100+ channels
Acoustic emission sensors	GI40/ G40 for tank bottom corrosion; GI150 for tank body cracks
Sampling rate	10M/s, 16-bit
Waveform collection	Support
Analog filters	High-pass filters: 20kHz, 100kHz, 400kHz; Low-pass filters: 100kHz, 400kHz, 1200kHz
Digital filters	1KHz-2.5MHz
Dimension	4-channel chassis: 320mm × 125mm × 50mm; (Length x Width x Height) 20-channel chassis: 308mm × 225mm × 133mm; (Length x Width x Height) 48-channel chassis: 308mm × 368mm × 133mm; (Length x Width x Height)
Advantages	USB3.0 high-speed data transmission, good expansion ability, stable performance, accurate defect location function. Suitable for regular detection.

SWAE Software

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.

Xingsan Joint Station Case: online detection of AE from storage tanks

Sensor Arrangement:

For example, nine sensors were evenly arranged around the outer wall about 50 cm above the bottom plate, avoiding discontinuous locations such as pipes and manholes as much as possible, with a horizontal spacing of about 7.8 meters.

Fig 1.1 Sensor Arrangement

Data Collection and Analysis:

Acoustic emission testing of the tank for 2 hours:

Fig 1.2 Tank #2 Channel - Hits Correlation Graph

Fig 1.3 Tank #2 Arrival time - Energy Correlation Graph

Fig 1.4 Tank #2 TDOA Location Map for 2h

Fig 1.5 Location Map when Pressure Maintaining

Test results

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.

Principle:

When corrosion defects or leakage occur on the bottom plate of the storage tank, acoustic emission waves are generated. The sensors receive the acoustic waves, which are then processed and analyzed by the acoustic emission acquisition unit. The result signals are transmitted to the cloud server through a 4G/WiFi network, and users log in to the cloud platform (private cloud/Qingcheng cloud) to remotely view the data and set rating criteria. The system automatically provides rating results based on the criteria. Once the alarm threshold is reached, an alarm is automatically pushed.

System Composition:

Acoustic emission sensors, acoustic emission acquisition instrument (signal acquisition and analysis and communication), cloud servers (cloud server IoT platform/LAN server/computer/mobile phone, etc.), customer terminals (mobile phone, PC, etc.).

Device Module	RAEM1-6 Multichannel AE system
Operation system	Linux
Channels	6 channels, can be cascaded to 100+ channels
Acoustic emission sensors	GI40/ G40 for tank bottom corrosion; GI150 for tank body cracks
Sampling rate	2M/s, 16-bit
Waveform collection	Support
Analog filters	High-pass filters: 30kHz, 125kHz; Low-pass filters: 80kHz, 175kHz
Digital filters	1KHz-1.0MHz
Communication	WiFi/ 4G
Dimension	Length x Width x Height: 22cm × 13cm × 8cm
Advantages	Based on the Linux operating system, it has stable performance, wireless communication capability, and is suitable for long-term remote unmanned monitoring. The devices can be cascaded to form a large-scale monitoring system.

Principle:

When corrosion defects or leakage occur on the bottom plate of the storage tank, acoustic waves (acoustic emission) are generated. The acoustic emission acquisition unit receives the signals, processes and analyzes them, and transmits them to the cloud server through a 4G/WiFi/LAN network. Users log in to the cloud platform (private cloud/Qingcheng cloud) to remotely view data and set rating criteria. The system automatically gives rating results based on the criteria. Once the alarm threshold is reached, an alarm is automatically pushed.

System Composition:

Acoustic emission acquisition unit (sensors, signal acquisition and analysis, communication), cloud server (cloud server IoT platform/LAN server/computer/mobile phone, etc.), client terminal (mobile phone, PC, etc.).

Device Module	RAEM1
Operation system	Linux
Channels	Single channel
Acoustic emission sensors	GI40/ G40 for tank bottom corrosion; GI150 for tank body cracks
Sampling rate	2M/s, 16-bit
Waveform collection	Support
Analog filters	High-pass filters: 30kHz, 125kHz; Low-pass filters: 80kHz, 175kHz
Digital filters	1KHz-1.0MHz
Communication	WiFi/ 4G/ RS-485
Advantages	RAEM1 has built-in sensors, signal acquisition, signal processing, data transmission, battery power supply, and wireless clock synchronization. Its strong magnetic bottom can be directly attached to the metal tank wall during installation. Generally applicable to metal storage tanks, it can be remotely monitored without human intervention or can do the traditional AE testing on-site.

Principle:

When corrosion defects or leakage occur on the bottom plate of the storage tank, acoustic waves (acoustic emission) are generated. The acoustic emission acquisition unit receives the signals, processes and analyzes them, and transmits them to the cloud server through the PoE router. Users log in to the cloud platform (private cloud/Qingcheng cloud) to remotely view data and set rating criteria. The system automatically gives rating results based on the criteria. Once the alarm threshold is reached, an alarm is automatically pushed.

System Composition:

Acoustic emission acquisition unit (sensors, signal acquisition and analysis), router, cloud server (cloud server IoT platform/LAN server/computer/mobile phone, etc.), client terminal (mobile phone, PC, etc.).

Device Module	BWM1
Channels	Single channel; multiple channels in series connection
Acoustic emission sensors	GI40/ G40 for tank bottom corrosion; GI150 for tank body cracks
Sampling rate	2M/s, 16-bit
Waveform collection	Support
Analog filters	High-pass filters: 30kHz, 125kHz; Low-pass filters: 80kHz, 175kHz
Digital filters	256-order FIR filter, any pass-through, high-pass, low-pass and band-pass settable from 0kHz-1000kHz
Communication	Ethernet
Dimension	507*50*43mm (waterproof plug included)
Advantages	The layout of this scheme is in chain series connection. The chain connection refers to the AE acquisition units are connected in series via PoE using Ethernet cables. Data transmission and power supply are both achieved through PoE, simplifying the wiring needs.