Hydraulic testing of gas bottles

The acid test of the development of gas bottle is the hydraulic test,burst test and the stretch.
Out of the many bottles which had passed radiography, five bottles were picked at random by the customer and these five bottles formed a lot which are sent for hydraulic test. One bottle picked from this lot randomly is sent for burst test after hydraulic test.
The hydraulic test pressure is in excess of 350 atm. and burst pressure is in excess of 700 atm. Since these pressure are very high, for the sake of safety, the gas bottle prepared for hydraulic test was kept in a pit and covered with sand bags.The hydraulic pressure has to be raised in an incremental manner as given in the specification.We used a computer controlled hydraulic testing machine.The Incremental pressure raise and the final hydraulic pressure was programmed. Once the hydraulic test was started the machine took over and stopped when the desired hydraulic pressure was achieved. The hydraulic test continued to establish the burst pressure of the selected bottle. At the end of the test the hydraulic test pressure and burst pressure was read out from the machine. The full testing sequence was recorded and a print out could be taken at the end of the test.
Initially, when we used commercially pure titanium wire for welding larger bottle of 8.5mm thickness we had some failures.But once we switched over to 3Al-2V filler wire we did not have a single failure.
Hundreds of bottles have been supplied to DRDL for their use. Even today BHPV is the preferred vendor for these bottles.