PSI - Issue 60

Rohan Nair et al. / Procedia Structural Integrity 60 (2024) 93–114 Rohan Nair / Structural Integrity Procedia 00 (2023) 000–000

99

7

CS5

CS3

Fig. 8: Test article with cir-seam reworks RW1 and RW2

During fabrication of the test article, process related reworks were encountered at 3 cir-seam joint locations, three on CS-5, one each on CS-3 and CS-4 and the same were subjected to RW1 repair welding. The locations of process related weld repairs are shown in Fig. 8. Prior to all pressure tests (proof pressure, pressure cycling and ultimate pressure), Test article was subjected to mass spectrometric helium leak detection (MSLD) leak tests [9] to rule out any leaks, deformations, cracks or major porosity in the weld and interface regions in fabricated condition. The maximum leak rates permissible for specified locations are shown in table-2.

Table. 2: Permissible leak rates for weld and interfaces. Location

Weld

Interfaces

Specification (mbarL/sec)

10 -6

10 -4

3. Experimental 3.1.

Acceptance and Qualification tests : To qualify the new source and processes, fixtures, toolings used for fabrication of water tank, the test article was subjected to a series of acceptance and qualification tests. The test setup was finalized such that all the long seam and cir-seam welds, adaptor welds and flange welds are qualified in the same test setup. Before finalizing the pressure testing range and schemes, the MEOP and number of pressure cycles experienced by the water tank had to be confirmed and this is to be simulated during qualification tests. The maximum expected operating pressure (MEOP) experienced by Water tank is 5.1 bar (gauge). The number of proof pressure cycles experienced by water tank was evaluated to be 8 and 12 cycles respectively. The analytical approach used for fixing the no. of pressure