Thermal Radiation Hazards from Gas Pipeline Rupture Fireballs

Increasing world-wide demand for gas is resulting in an increased network of gas piping which poses potential hazards to the natural and man-made environment in proximity to the pipelines. In this work we report experimental measurements of the thermal radiation levels generated by fireballs from two fullscale, below-ground, natural-gas pipeline ruptures. The tests were carried out at the DNV GL’s Spadeadam Test Site simulating the rupture of a 1219 mm diameter pipe carrying high pressure natural gas (at 13.4 MPa -nominal gauge pressure). The duration of the fireball and the maximum heat fluxes (as high as 70 kW/m2 at 200 m downwind) were well predicted by current simple mathematical models when a reasonable radiative fraction of the total energy release was assumed. The empirical radiant fraction equation adopted by OGP was shown to overpredict the incident heat flux in these tests. In the second test the grass surrounding the test location was ignited and other vegetation showed significant thermal damage. To interpret such data correctly and to evaluate the hazards, to natural and man-made environments, more information is needed on the effects of short exposure times (of the order of a few seconds) to high transient heat fluxes.