Release of LH2 during transfer

During an LH2 transfer from a tanker, the burst disc ruptured at 50 psi (ca. 3.5 bar). The operator had turned on the pressure valve and left it unattended, permitting pressure build-up past the allowed 30 psi.
Pressure limit for the operation was 30 psi (ca. 2 bar).

[Ordin, NASA (1974)]

The INITIATING CAUSE was the excess of maximal allowed pressure and consequent correct rupture of the burst disc.

The ROOT CAUSE was the not following of the prescribed procedure. The operator left pressure valve unattended, permitting pressure build-up past the allowed 30 psi.

burst disc

Hydrogen transfers are characterised by risks related to frequent connection-connections operations involving a flexible hoses and the series of manual operations required by the operators, who are often also the truck drivers. These operations need strong focus and continuous supervision. The operators need to follow well-designed procedures and be instructed on the consequences of not following them.