Delft Aerospace Rocket Engineering have been investigating the safe storage of liquid oxygen that could feature in the next rocket project. The team has been looking into 3 different tank designs in order to achieve this, a welded aluminium design, aluminium with sealed bolt on bulkheads and a composite design with an inner liner.
Prototypes of each tank will be built and tested to 90 Bar (9MPa) to verify the design and methods on construction.
You can read the full update from DARE here.
I will be following this closely as I recently drew up a bolted sealed bulkhead design for test stand tanks, but was put off by the sealing at cryogenic temperatures as talked about and tried in a Roberts Rocket Project Update. The cost of the FEP spring o-ring seal or Astra Seal as they are also called is also a factor in the design. Robert claimed USD$235 (in 2014) each for a 2-246 seal size. At this cost, I could get a custom made welded aluminium tank fabricated that would meet my needs.