PSI - Issue 60

Varsha Florist et al. / Procedia Structural Integrity 60 (2024) 614–630 6 Varsha Florist, Santhoshkumar R, A. Vamsi, Sajju V, Sarath Mohan, Sanjeev Kumar, Dhanoop A, Venukuttan C, M.K. Sundaresan, SVS Narayana Murty / Structural Integrity Procedia 00 (2024) 000 – 000

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This modification, in turn reduces the number of weld joints to be inspected through non-destructive examination Chitaranjan Pany (2021), Subhananda Rao (2005). The schematic of the weld joints for both versions of the pressure vessels is presented in Fig. 4. This material can be easily formed in solution treated condition and direct aging can be adopted to relieve stress generated during fabrication and achieve desired mechanical properties by precipitation hardening. The 15-5 PH flow formed cylindrical shells for the pressure vessel were realized by adopting backward flow forming technique. The flow forming route adopted for the realization of the cylindrical shell is presented as Fig. 5. A preform of 30mm thickness in solution treated condition was flow formed initially to 18 mm thick shell in the 1st pass and further to 10 mm thick in the 2nd pass. This 10 mm shell was subjected to solution treatment at a temperature of 1038ºC, as per AMS 5659. The shell is further flow formed to a thickness of 4.2mm during 3rd pass, keeping the ends and bracket welding locations locally at 10mm. Finally, both ends of the shell are machined to 4.5mm thickness to enable circumferential weld with fore and aft end domes.

Fig. 5. Flow forming sequence of the cylindrical shell of 15-5 PH tank

In order to arrive at the weld parameters and assessing weld efficiency and structural margins, a sub-scale tank as shown in Figure-6 was realized using a flow formed sub-scale shell of nominal diameter of 200 mm with the same thickness same as that of the full-scale version. The mechanical properties and weld efficiency were assessed and the sub-scale tank was successfully burst tested. The tank has failed (burst) at a pressure of 565 bar, matching to the