Ferrite Testing a significant Non-destructive Testing method for Weld inspection is Vacuum box testing which is used to locate leaks in pressure boundaries that cannot be directly pressurized. The main component of this method is a bubble-forming solution applied to a local area to be tested on the pressure boundary by flowing, spraying or brushing. It creates differential pressure across that local area.
It forms the bubble as leakage gas passes through the solution. This method provides the detection of through-thickness leaks & used for testing welds. Cracks, pores & lack of fusion are causes of leaks detectable by this method.
The 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 the area to be examined.
Advantages: 1) It provides an immediate indication in terms of visuals 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, the 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 for the last decade. IXAR is carrying out an inspection within the parameters of ASME Section V, Article 10, and Appendix-II and also ASTM E515.