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F. Qiu et al.
15.1 Introduction
Acoustic emission (AE) testing technology is a nondestructive testing method which
can quickly evaluate the structural integrity of pressure vessels [1]. It can be used for
on-line monitoring of storage tanks without stopping production, and finally make
a reasonable safety evaluation for storage tanks. The acoustic source identification
technology for tank floor corrosion can reflect the number of defect acoustic sources
and the actual defect acoustic emission activity [2, 3]. Therefore, in the acoustic
emission detection of tank corrosion state, the location source is an important index
to evaluate the detection results, and the results have high reference value.
However, the acoustic source recognition technology of tank bottom corrosion still
has some limitations. Tank bottom acoustic source localization is effect by complex
sonic, multiple signals and threshold setting. At the same time, due to the design of
the tank has tended to be larger, the acoustic wave from tank bottom defects maybe
attenuate seriously. The number of acoustic position events will be lost. Acoustic
activity cannot reflect the condition of defects reasonably. Safety assessment results
of the tank bottom corrosion will not be accuracy [4]. Therefore, a new acoustic source
identification method is need for these problem solution. Not only the reliability of
position can be improved, and the activity of defects can be reflected reasonably.
Both triangulation location and regional positioning applications can be combined
for small tank detection, but also the requirements of regional location for large tanks
can be met. Therefore, this paper proposes a method of tank bottom acoustic source
identification to solve the above problems.
15.2 Acoustic Source Location and Identification Method
of Tank Bottom Corrosion
In AE testing process, measure strategy of tank bottom location is setting several
sensors uniform on tank wall outside nearby bottom based on the size of tank.
Figure 15.1 is a triangle location map of tank bottom, setting six sensors around the
tank uniformly. Triangle location are made up every three sensors location, forming
a total of six groups.
Although the traditional location method can form multi triangle location group,
missed inspection and misjudgment maybe appear. Because tank bottom corrosion
signal is weak and large tank bottom has serious attenuation [5]. Therefore, it is
necessary to place the sensor inside the tank. The sensor inside and the sensor outside
the tank are in the same plane. For small storage tank, it can reduce the misjudgment
of acoustic source and prevent the “loss” of AE signal. For large storage tanks,
the detection coverage area can be increased in the area positioning. As shown in
Fig. 15.2, No. 7 sensor is placed at the center of tank bottom plate to form triangle
positioning with 6 sensors around the tank wall. S is an acoustic source setting at the
tank bottom, the location is shown in Fig. 15.3.
F. Qiu et al.
15.1 Introduction
Acoustic emission (AE) testing technology is a nondestructive testing method which
can quickly evaluate the structural integrity of pressure vessels [1]. It can be used for
on-line monitoring of storage tanks without stopping production, and finally make
a reasonable safety evaluation for storage tanks. The acoustic source identification
technology for tank floor corrosion can reflect the number of defect acoustic sources
and the actual defect acoustic emission activity [2, 3]. Therefore, in the acoustic
emission detection of tank corrosion state, the location source is an important index
to evaluate the detection results, and the results have high reference value.
However, the acoustic source recognition technology of tank bottom corrosion still
has some limitations. Tank bottom acoustic source localization is effect by complex
sonic, multiple signals and threshold setting. At the same time, due to the design of
the tank has tended to be larger, the acoustic wave from tank bottom defects maybe
attenuate seriously. The number of acoustic position events will be lost. Acoustic
activity cannot reflect the condition of defects reasonably. Safety assessment results
of the tank bottom corrosion will not be accuracy [4]. Therefore, a new acoustic source
identification method is need for these problem solution. Not only the reliability of
position can be improved, and the activity of defects can be reflected reasonably.
Both triangulation location and regional positioning applications can be combined
for small tank detection, but also the requirements of regional location for large tanks
can be met. Therefore, this paper proposes a method of tank bottom acoustic source
identification to solve the above problems.
15.2 Acoustic Source Location and Identification Method
of Tank Bottom Corrosion
In AE testing process, measure strategy of tank bottom location is setting several
sensors uniform on tank wall outside nearby bottom based on the size of tank.
Figure 15.1 is a triangle location map of tank bottom, setting six sensors around the
tank uniformly. Triangle location are made up every three sensors location, forming
a total of six groups.
Although the traditional location method can form multi triangle location group,
missed inspection and misjudgment maybe appear. Because tank bottom corrosion
signal is weak and large tank bottom has serious attenuation [5]. Therefore, it is
necessary to place the sensor inside the tank. The sensor inside and the sensor outside
the tank are in the same plane. For small storage tank, it can reduce the misjudgment
of acoustic source and prevent the “loss” of AE signal. For large storage tanks,
the detection coverage area can be increased in the area positioning. As shown in
Fig. 15.2, No. 7 sensor is placed at the center of tank bottom plate to form triangle
positioning with 6 sensors around the tank wall. S is an acoustic source setting at the
tank bottom, the location is shown in Fig. 15.3.