38 Acoustic Emission Testing for the Large Vacuum System …
433
38.4 Test Process and Result Evaluation [1–3]
The acoustic emission test is carried out in combination with the vacuum test of
the ball tank system. The two ball tanks are tested separately. First, we close the
gate valve FM-02 between the two ball tanks and the gate valve FM-04 between the
V-06 vacuum ball tank and the wind tunnel, and carry out the vacuum test on the
V-06 vacuum ball tank. The specific vacuum test is carried out in stages according to
50,000, 10,000, 5000 Pa and 23.7 Pa, and enough inspection time is kept at all levels.
After the vacuum test of V-06 vacuum ball tank, the pressure of V-06 ball tank and
connecting pipes is maintained, and then the vacuum test of V-05 vacuum ball tank
is conducted according to the same stage. According to the measurement of sound
velocity, the result is 4900 m/s in Region I and III, and 4700 m/s in Region II and IV.
The attenuation curve and pulse table are shown respectively in Figs. 38.3 and 38.4.
During the acoustic emission monitoring of V-06 vacuum ball tank, according to
NB/T 47013.9-2012 “Nondestructive Testing of Pressure Equipment Part 9: Acoustic
Emission Testing”, no effective acoustic emission source is found that increases
continuously with the increase of negative pressure. The situation of acoustic emission activity source above level II is shown in Table 38.2. At the stage of pumping
to 50,000 Pa, two acoustic emission activity sources are found in region I and three
acoustic emission activity sources are found in region II, At 50,000 Pa in the pressure
maintaining stage, one acoustic emission active source is found in region I and region
II respectively. At the 50,000–10000 Pa stage, three acoustic emission active sources
are found in region I and four acoustic emission active sources are found in region II.
At the 10,000–5000 Pa stage, one acoustic emission active source is found in region
I and region II respectively. At the 5000–5000 Pa stage, one acoustic emission active
Fig. 38.3 The attenuation curve
433
38.4 Test Process and Result Evaluation [1–3]
The acoustic emission test is carried out in combination with the vacuum test of
the ball tank system. The two ball tanks are tested separately. First, we close the
gate valve FM-02 between the two ball tanks and the gate valve FM-04 between the
V-06 vacuum ball tank and the wind tunnel, and carry out the vacuum test on the
V-06 vacuum ball tank. The specific vacuum test is carried out in stages according to
50,000, 10,000, 5000 Pa and 23.7 Pa, and enough inspection time is kept at all levels.
After the vacuum test of V-06 vacuum ball tank, the pressure of V-06 ball tank and
connecting pipes is maintained, and then the vacuum test of V-05 vacuum ball tank
is conducted according to the same stage. According to the measurement of sound
velocity, the result is 4900 m/s in Region I and III, and 4700 m/s in Region II and IV.
The attenuation curve and pulse table are shown respectively in Figs. 38.3 and 38.4.
During the acoustic emission monitoring of V-06 vacuum ball tank, according to
NB/T 47013.9-2012 “Nondestructive Testing of Pressure Equipment Part 9: Acoustic
Emission Testing”, no effective acoustic emission source is found that increases
continuously with the increase of negative pressure. The situation of acoustic emission activity source above level II is shown in Table 38.2. At the stage of pumping
to 50,000 Pa, two acoustic emission activity sources are found in region I and three
acoustic emission activity sources are found in region II, At 50,000 Pa in the pressure
maintaining stage, one acoustic emission active source is found in region I and region
II respectively. At the 50,000–10000 Pa stage, three acoustic emission active sources
are found in region I and four acoustic emission active sources are found in region II.
At the 10,000–5000 Pa stage, one acoustic emission active source is found in region
I and region II respectively. At the 5000–5000 Pa stage, one acoustic emission active
Fig. 38.3 The attenuation curve