Filling and Purging Requirements for High Pressure Containers (23)
Criticality: Medium
Progress: Not Addressed
Score: 24
DOT Relevance: §173.302
Description of Key Area
High pressure hydrogen storage technologies are being developed
to address the low storage density—both gravimetric and volumetric—of gaseous
hydrogen. Fast filling of high pressure gaseous hydrogen containers can result
in significant gas temperature increases due to heat of compression. Plastic
lined composite containers can have material temperature limits that can be
exceeded if proper procedures and controls are not employed. Additionally,
thermally-activated pressure relief devices could suffer thermal degradation
from repeated exposure to high gas temperatures. Purging of plastic-lined
containers Rapid depressurization of plastic lined containers can place
potentially harmful thermal stresses on sealing/mating areas between the
plastic liner and metal connecting hardware (bosses). Also, it also not
generally recommended to bring the internal pressure of a plastic-lined
container appreciably below atmospheric pressure as the vacuum pressure can
lead to the separation of the liner from the structural composite overwrap,
potentially damaging the liner.
Discussion of Criticality
It is anticipated that as these storage technologies develop,
their proponents will determine any unique conditions or procedures for
container filling. It is also anticipated that as early products are brought to
market, initial regulatory coverage will be via special permits which will
likely require filling to be performed by the manufacturer or their designated
agents, providing a level of control over the filling process through
manufacturers’ developed practices.
Discussion of Progress
Most high pressure storage technologies are currently being
developed for vehicular applications and are at the prototype stage. They are
not yet in use for hydrogen transport. Progress was assessed as “Not
Addressed”.
Recommendations
As development and deployment activities increase, initially the
special permit process could be used to incorporate any special handling
requirements during filling. With sufficiently wider deployment, requirements
could be considered for incorporation into regulatory structure.
|