438
Y. Kaibai et al.
element analysis and calculation, the maximum stress of this section of pipeline is
321.08 MPa, which is located at the lower end of the horizontal axial bellows short
section, i.e. near the lower part of the bellows, there is a bolt bending and deforming
position. Through the analysis, the phenomenon of gate valve lifting and displacement is due to the difference of single upper and lower surface area of 144° elbow
of DN3600 connecting pipeline between two ball tanks, which is about 62,000 cm
2 ,
and the edge is generated when it is close to the vacuum state. The upward thrust of
the elbow angle split line is about 620 KN, and the total upward thrust of the two
elbows is about 1240 KN. The pipe support between the two ball tanks is a sliding
support, which has no restriction on the pipe and the gate valve, so the gate valve is
lifted up and displaced horizontally.
38.5 Existing Problems
1. Due to the positioning method, rib plate structure, large skirt and other reasons, it
is difficult to locate. The pipeline part can realize the triangle surface positioning,
and the ball tank part can only realize the regional positioning.
2. There are noise signal sources such as personnel inspection and inspection in
some vacuum stages.
3. The stress release of the rib plate inside the tank body becomes the acoustic
emission signal source, causing interference.
4. The vacuum test belongs to the negative pressure test, which is different from
the usual pressure rise test.
38.6 Conclusion
In view of the acoustic emission testing of the large vacuum system under the vacuum
pumping test state, the following conclusions with engineering significance can be
drawn:
1. Acoustic emission testing can monitor the vacuum test process of spherical tank
and pipeline system in real time, and evaluate the results effectively and reliably.
2. The large vacuum system can effectively carry out acoustic emission monitoring
on the stress concentration part in the vacuum test state, and realize the instability
prediction and integrity evaluation of the whole structure through the measures
of noise elimination and routine nondestructive testing retest.
3. Acoustic emission testing can monitor the deformation and stress release of the
stiffened plate structure in real time.
4. Because of the complex structure and the stiffener inside, it is difficult to
realize the plane positioning in all monitoring areas of the vacuum ball tank.
Acoustic emission testing can provide an effective method for monitoring and
post inspection of the large vacuum system.
Y. Kaibai et al.
element analysis and calculation, the maximum stress of this section of pipeline is
321.08 MPa, which is located at the lower end of the horizontal axial bellows short
section, i.e. near the lower part of the bellows, there is a bolt bending and deforming
position. Through the analysis, the phenomenon of gate valve lifting and displacement is due to the difference of single upper and lower surface area of 144° elbow
of DN3600 connecting pipeline between two ball tanks, which is about 62,000 cm
2 ,
and the edge is generated when it is close to the vacuum state. The upward thrust of
the elbow angle split line is about 620 KN, and the total upward thrust of the two
elbows is about 1240 KN. The pipe support between the two ball tanks is a sliding
support, which has no restriction on the pipe and the gate valve, so the gate valve is
lifted up and displaced horizontally.
38.5 Existing Problems
1. Due to the positioning method, rib plate structure, large skirt and other reasons, it
is difficult to locate. The pipeline part can realize the triangle surface positioning,
and the ball tank part can only realize the regional positioning.
2. There are noise signal sources such as personnel inspection and inspection in
some vacuum stages.
3. The stress release of the rib plate inside the tank body becomes the acoustic
emission signal source, causing interference.
4. The vacuum test belongs to the negative pressure test, which is different from
the usual pressure rise test.
38.6 Conclusion
In view of the acoustic emission testing of the large vacuum system under the vacuum
pumping test state, the following conclusions with engineering significance can be
drawn:
1. Acoustic emission testing can monitor the vacuum test process of spherical tank
and pipeline system in real time, and evaluate the results effectively and reliably.
2. The large vacuum system can effectively carry out acoustic emission monitoring
on the stress concentration part in the vacuum test state, and realize the instability
prediction and integrity evaluation of the whole structure through the measures
of noise elimination and routine nondestructive testing retest.
3. Acoustic emission testing can monitor the deformation and stress release of the
stiffened plate structure in real time.
4. Because of the complex structure and the stiffener inside, it is difficult to
realize the plane positioning in all monitoring areas of the vacuum ball tank.
Acoustic emission testing can provide an effective method for monitoring and
post inspection of the large vacuum system.