Large Scale Experiments to Study Hydrogen Pipeline Fires

Abstract

To gain an understanding of the risks associated with a hydrogen pipeline failure, Air Products commissioned GL Industrial Services UK to perform two experiments where a buried 6″ diameter pipeline at an initial pressure of 60 bar was intentionally failed using an explosive charge to generate a full bore release of hydrogen gas from two open ends, simulating a pipeline rupture event in which a ground crater is formed naturally in the surrounding soil by the released gas. The first experiment was performed with the pipe buried 1m deep in a typical soil and the second experiment was performed with a 1m deep backfill of a mixture of sand and soil. The hydrogen released was ignited immediately following the pipeline failure. Following initiation of each experiment, the properties of the hydrogen gas release and resulting fire were measured. The two experiments were conducted under similar conditions, with the main differences being the nature of the soil used for the pipeline backfill and the wind speed (which was significantly higher in the first experiment). The initial pipeline pressure was very similar in the two experiments, with complete depressurisation of the gas pipeline and reservoir taking place over a period of approximately 80 seconds. Maximum flame lengths of up to approximately 100m were measured in each experiment. A number of previous experimental programmes have been carried out by GL in order to investigate the fire characteristics of natural gas releases from ruptured pipelines, conducted under nominally similar conditions. Recently, experiments of this type were also conducted to investigate releases of mixtures of hydrogen and natural gas. The paper will present a high level overview of the results including a discussion of the observed differences between the release and fire behaviour of the different gases.

A model for the initial stages following the rupture of a natural gas transmission pipeline

“…Independent evidence of the generality of the model is available from data obtained by DNVGL on experimental studies involving ruptures to buried pipelines containing hydrogen, Acton et al (2010b).…”

Modeling of underground hydrogen pipelines

“…The test assembly consisted of a 6 in. nominal bore test section buried 1 m below grade and connected to a 163 m 3 gas storage reservoir ]. The gas ignited immediately in both tests, probably due to the explosive charge used to rupture the pipe.…”

Comparative Study on Blast Wave Propagation of Natural Gas Vapor Cloud Explosions in Open Space Based on a Full-Scale Experiment and PHAST

“…2 More recently, two pipeline rupture experiments were performed using a similar test rig with a 150 mm diameter pipeline pressurized with natural gas. 3 …”

“…2 More recently, two pipeline rupture experiments were performed using a similar test rig with a 150 mm diameter pipeline pressurized with natural gas. 3 Previous studies of VCEs in open space have shown that more reactive fuels are more susceptible to flame acceleration through the gas pipeline. 4−6 On a theoretical aspect, VCEs are usually analyzed by means of simplified models, such as the TNT equivalent method and its later developments.…”

“…Several large-scale experimental studies for high-pressure natural gas pipelines have been conducted in support of the development of the internationally used pipeline risk assessment for natural gas pipelines, and two pipeline rupture experiments were performed at full scale . More recently, two pipeline rupture experiments were performed using a similar test rig with a 150 mm diameter pipeline pressurized with natural gas . Previous studies of VCEs in open space have shown that more reactive fuels are more susceptible to flame acceleration through the gas pipeline. − On a theoretical aspect, VCEs are usually analyzed by means of simplified models, such as the TNT equivalent method and its later developments. − Recently, several models have been proposed to predict the intensity of the blast wave induced by an explosion. − …”