ABSTRACT
On completion of welding the nozzle to shell, pad to nozzle, and pad to shell, it is recommended to carry out an air test of the pad. This will reveal any through holes in any of the welds mentioned. Even though this test is not mandatory, it is invariably carried out to detect defects in welding which otherwise could be detected only during the hydrostatic test. In such cases, the repair of the defect becomes too expensive in terms of money and time. The test becomes very significant in the case of thin-walled vessels where the number of passes of weld is fewer. The test is carried out upon completion of all welding and the dressing of the nozzle welding to form the contour as 148desired in the drawings and shall obviously be before the postweld heat treatment (PWHT).
