This paper compares hazard and risk factors related to transporting hydrogen in natural gas pipelines. Properties of hydrogen-compressed natural gas (HCNG) blends and typical materials for the construction of transmission and distribution systems are evaluated to address the key properties that might impact hazard and risk factors. ASME (American Society of Mechanical Engineers) standards B31.8 and ASME B31.12 are reviewed for key differences applicable to HCNG blends. A methodology to identify compliance gaps and mitigate deficiencies if HCNG blends are transported in natural gas transportation systems is proposed.
The paper presents the results of investigation and engineering analysis by Exponent of the failure of a 220 MVA generator step-up transformer in Southern California. The incident was caused by a dielectric breakdown from the high side phase C bushing to the side wall of the transformer. The ensuing fire continued for 27 hours, fueled by approximately 11,000 gallons of dielectric HYTRANS 61 oil. The paper will discuss the investigation, conducted per the IEEE C57.125 “Guide for Failure Investigation, Documentation, and Analysis for Power Transformers and Shunt Reactors.” [1], and the engineering review and analysis to identify the likely failure scenario(s).
While movement of people in crowds and fire drills has been studied by numerous investigators, little data exist for real fire evacuations. This is largely due to the difficulty in establishing an accurate position-time history for the evacuees. The evacuation of the World Trade Center North and South Towers on September 11, 2001 was unique in that major, catastrophic events occurred at distinct times during the evacuation. In this paper, 14 evacuation case studies are presented in which the evacuee reported their position at these known points in time to the media. From this position-time history, the descent rate of these evacuees could be determined. These descent rates are not necessarily representative of the evacuation population in general, but they do provide some distinct data points which are of value to the fire protection and building evacuation community in assessing evacuation from high-rise buildings.
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