Type approval of composite gas cylinders – Probabilistic analysis of standards' requirements concerning minimum burst pressure

Abstract Gas cylinders made from composite materials receive growing popularity in applications where light weight is of advantage. At the same time manufacturers are interested in cutting cost and weight through material reduction for better acceptance of a product, e.g. H 2 -vehicles. This requires a better understanding of safety relevant properties. The safety determination of current standards is mainly based on the minimum burst pressure of a few specimens. Various research projects were conducted aiming at reducing minimum burst pressure requirements without compromising safety. No satisfying results were found. While looking at reliability aspects it could be concluded, that the minimum burst pressure of unused specimens is not a satisfying criterion for safety during service life. This paper introduces first ideas for a method to determine one aspect of reliability of composite gas cylinders, employing probabilistic analysis of burst pressures of a sample of specimens. This can create potential for saving material cost while granting a higher safety level than the current method. Additionally, degradation over service time can be assessed.