Criticality: High Progress: Addressed, Not Adequately Score: 20 DOT Relevance:
Description of Key Area
High pressure tubing and fittings will be required to fill and
vent cylinders and to connect cylinders.
Discussion of Criticality
As pressure increases, making the connection of the tubing and
fittings becomes more difficult. Connections are often made by plastically
yielding portions of the tubing so that the fittings will not leak or fail to
hold. As contained pressure increases, the tube walls thicken, making plastic deformation
difficult and possibly inducing stress concentrations. This may compromise the
integrity of the joint between the tubing and the fittings. If the joint fails,
hydrogen can leak and ignite.
Discussion of Progress
Industry is working on new methods of connecting tubing and
fittings.
Recommendations
Industry and DOT should monitor field experience with high
pressure tubing and fittings to ensure that safe, reliable components are being
developed. As experience progresses, standards should be developed for the
qualification of high pressure tubing and fittings.
