Vacuum Box Testing (VBT)
A non-destructive test performed to try to find weld seam leaks is vacuum box testing. While a detergent solution is being applied to the test area, a vacuum box and compressor produce a high or low-pressure vacuum. As the detergent bubbles, leaks within the resulting pressure envelope become obvious. All inspections are performed in accordance
with either customer requirements or the restrictions of ASME Section V Article 10, Appendix II. It is one of the most popular techniques for tank leak identification throughout the In Service Storage tank inspection as well as newly erected storage tank inspection. Vacuum Corner boxes are used to identify leakage between tank shell to bottom plate Tee weld connections and flat corner boxes are used to detect tank leakage of bottom plates between weld joints. When Storage tank being manufactured or during periodic in-service inspections of storage tanks, It can be utilized to discover leaks in pipes, heat exchangers, condensers, containment linings, tank bottom plates, tank roofs, containment linings, and pipelines. Primary objective is, of course, to identify any leaks in the surface or joint being examined. According to ASME BPVC V article 10, the purpose of the vacuum box approach of bubble leak testing is to identify leaks in a pressure boundary that cannot be directly pressurized. All types of weld joints like lap joints in tank bottom plate, Fillet weld joints of shell to bottom plate, Butt weld joints of plain surfaces like hull area or body area can conduct vacuum box test in order to find out the leak. A vacuum gauge and hose connector are installed in the vacuum box before proceeding further into the testing. The welding line in the testing object is then treated with a soapy solution. After that, a vacuum is created inside the vacuum box by placing it over the testing object. Now that the object has been examined, any drop in vacuum pressure or the appearance of bubbles on the surface indicate that the weld has failed and the object is defective. The extremely popular leak testing method known as vacuum box testing is frequently used to check a variety of goods for faults, defects, leaks, or other issues.