Storage Tank Leak Test:
An unintended crack, hole, or porosity in an enclosing wall or joint that must contain or exclude various fluids and gases and permits the escape of a closed medium is referred to as a leak. In Storage tank, connectors, gaskets, weld joints, material flaws,bottom plate etc. are frequently critical leak points. A leak test technique is typically quality inspection assurance step to ensure the integrity of the storage tank, and it should ideally be a non-destructive test with no adverse impact on the environment or users. There are several leak-testing methods available, ranging from extremely viable methods to systems that are more intricate.
Vacuum Box Testing :
Throughout the In Service Storage tank inspection , vacuum box testing is the widely used methods for tank leak detection. Flat Corner box are used to detect the tank leakage of bottom plates in between weld joints and corner box are used to detect leakage in between tank shell to bottom plate Tee weld joints. They can be used to find leaks in pipelines, heat exchangers, condensers, containment liners, tank bottom plate, tank roofs, containment linings, pressure vessels during manufacturing, or In Service periodic inspection of storage tank . Naturally, the main goal of vacuum box testing is to find any leaks in the surface or joint under inspection. The aim of the vacuum box approach of bubble leak testing, as stated in ASME BPVC V article 10, is to find leaks in a pressure boundary that cannot be directly pressurized. This is precisely what happens with tanks, which must be made with a vacuum box because of their vast capacity and inability to be over pressurized in order to verify the weld seams.
Vacuum Box Test stages in Storage tank:
The following situations involving the construction of a welded storage tank can be tested using a vacuum box.
- If approved, an internal shell-to-bottom weld should be used in the first pass rather than MT, PT, or Pen. Oil.
- In between the bottom plate welds joints
- If not air tested, the welds of roofs that are intended to be gas-tight.
- If not tested with penetrating oil, in any internal floating roof seams exposed to liquid or vapor.
- For leak protection, in flexible membrane liners’ seams.
- Unless tested with penetrating oil, in welded shell joints above the hydrostatic test water level.
within the shell-to-bottom weld joints.