A significant Non-destructive Testing method for Weld inspection is Vacuum box testing which is used to locate leaks in pressure boundary that cannot be directly pressurized. The main component of this method is bubble forming solution applied to a local area to be tested of the pressure boundary by flowing, spraying or brushing. It creates a differential pressure across that local area. It forms the bubble as leakage gas passes through the solution. This method provides detection of through-thickness leaks & used for testing of welds. Cracks, pores & lack of fusion are causes of leaks detectable by this method.
Following are the applications of Vacuum Box Testing; 1) Lap Welds, butt welds, and shell to annular welds. 2) Piping system & Pressure Vessels 3) Tank Bottoms and 4) Objects on which a pressure differential can be created across area to be examined.
Advantages: 1) It provides an immediate indication in terms of visual of the location of any leaks present. 2) It helps to detect leaks within a given area.
Limitations: 1) Size and orientation of any leaks will have to be analyzed with a secondary NDT method. 2) During testing, standard surface temperature of the test material must be between 50C to 500
IXAR is engaging in performing Vacuum Box Testing for Oil & Natural Gas sector as well as cross country pipelines since last one decade. IXAR is carrying out inspection within parameter of ASME Section V, Article 10, and Appendix-II and also ASTM E515.
