Thermal History Resulting in the Failure of Lightweight Fully-Wrapped Composite Pressure Vessel for Hydrogen in a Fire Experimental Facility

We must improve our understanding of the thermal behaviour of composite gas storage in the event of fire in order to reduce the risk of bursting. In this research, results of pool fire tests were used to improve understanding of the failure mechanisms of epoxy carbon fibre composite pressure vessels with a polymeric liner (type IV vessel) designed for a working pressure of 70 MPa. The failure mode in a pool fire test depends on the storage design and on the initial pressure of the storage. For instance, for a 100 L type IV storage without any safety system, initial pressures of 70 MPa down to 52.5 MPa result in pressure vessels bursting, and initial pressures of 35 MPa down to 17.5 MPa lead pressure vessels to loss of liner tightness. The occurrence of one mechanism or the other is due to the predominance of either heat transfer through the wall, leading to a loss of tightness; or of the degradation of the materials, leading to bursting. Thermogravimetric analyses were carried out on the pressure vessel materials to determine the onset of degradation take during pool fire tests. The temperature measurements allowed for proper characterisation of the conditions leading to the loss of liner tightness. Temperature profiles were used to link the position of the composite degradation front to the loss of tensile strength leading to bursting.