What is vacuum box testing?
Vacuum box testing is a very popular leak-testing technique that is widely used to test various objects against defects, flaws, leaks, or other imperfections, being an efficient and effective method to test welded objects
Vacuum box testing can be used to test items that are capable of creating a pressure differential across the region to be examined. Vacuum boxes are used to test if there any leakage in welded parts of a tank or pipeline
To generate precise outcomes, these vacuum boxes are used to examine a tiny, particular part of a welded region.
How a Vacuum box testing working ?
Before the testing starts, a vacuum gauge and hose coupling are fitted in the box. Then a soapy solution is placed under test on the object’s welding line.
The vacuum box is then put over the test item and a vacuum inside the box is generated. Then the object is noted for either a vacuum fall or a surface bubble formation, in which case the weld is deemed defective.
There are two primary kinds of vacuum box technologies used for vacuum testing:
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High-pressure models are mainly used for inspection of above ground storage tanks that have been in service.
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Low-pressure models are used for weld integrity checks on new tank builds where gross defects are the main concern.
Vacuum box testing is carried out on all bottom plate lap welding and also corner welds and sometimes roof plate lap welds as well.
Vacuum Box Test Procedure:
Vacuum box testing on tank welds shall be performed in writing, authorized by all concerned in compliance with the code and contract requirements, vacuum testing procedure:
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List of reference codes and specifications
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Type of equipment proposed
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Range of pressure gauge and its calibration
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Details of bubble-forming solution
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Duration of test
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Overlap required during test
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Surface preparations and prior inspection requirements
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Temperature and light requirements on test surface
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Personnel qualification
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Evaluation criteria
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Repair and retests
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Inspection report format