352
H. Xu et al.
Table 29.1 Data processing method with leakage probability and events activity
Leakage probability
Events activity
I
II
III
IV
V
I
A
B
B
C
D
II
B
C
C
C
D
III
C
D
D
E
E
IV
D
E
E
E
E
Fig. 29.4 Different location graph are all rated as grade C
In PetroChina, we use leakage probability and events activity to evaluate the
corrosion severity of the tank floor, as shown in the Table 29.1.
29.2.2.2 The Grade Criteria is Different
Data evaluation results show that the location graph is different for the same AE
grade, such as these four different pictures in Fig. 29.4 are all rated as grade A.
In two different pictures of events activity are all evaluated as grade C.
So the rating of the AE results cannot just been evaluated by the event location
graph.
29.2.2.3 The Number of Grades of AE Results is Different
The number of grades of AE results is different. In ASTM [4], the data evaluation
results are divided into 3 grades. Paper [1] shows data evaluation results into 4 grades
[1]. And many companies have divided the AE results into 5 grades [2, 8, 9].