Numerical and Experimental Analysis of Fire Resistance for Steel Structures of Ships and Offshore Platforms

The requirements for the fire resistance of steel structures of oil and gas facilities for transportation and production of hydrocarbons are considered (structures of tankers and offshore platforms). It is found that the requirements for the values of fire resistance of structures under hydrocarbon rather than standard fire conditions are given only for offshore stationary platforms. Experimental studies on the loss of integrity (E) and thermal insulating capacity (I) of steel bulkheads and deck with mineral wool under standard and hydrocarbon fire regimes are presented. Simulation of structure heating was performed, which showed a good correlation with the experimental results (convective heat transfer coefficients for bulkheads of class H: 50 W/m2·K; for bulkheads of class A: 25 W/m2·K). The consumption of mineral slabs and endothermic mat for the H-0 bulkhead is predicted. It is calculated that under a standard fire regime, mineral wool with a density of 80–100 kg/m2 and a thickness of 40 to 85 mm should be used; under a hydrocarbon fire regime, mineral wool with a density above 100 kg/m2 and a thickness of 60–150 mm is required. It is shown that to protect the structures of decks and bulkheads in a hydrocarbon fire regime, it is necessary to use 30–40% more thermal insulation and apply the highest density of fire-retardant material compared to the standard fire regime. Parameters of thermal conductivity and heat capacity of the applied flame retardant in the temperature range from 0 to 1000 °C were clarified.

Evidence that modern fires may be unprecedented during the last 3400 years in permafrost zone of central Siberia, Russia

Recent climate change in Siberia is increasing the probability of dangerous forest fires. The development of effective measures to mitigate and prevent fires is impossible without an understanding of long-term fire dynamics. This paper presents the first multi-site palaeo-fire reconstruction based on macroscopic charcoal data from peat and lake sediment cores located in different landscapes across the permafrost area of Central Siberia. The obtained results show similar temporal patterns of charcoal accumulation rates in the cores under study, and near synchronous changes in fire regimes. The paleo-fire record revealed moderate biomass burning between 3.4 and 2.6 ka BP, followed by the period of lower burning occurring from 2.6 to 1.7 ka BP that coincided with regional climate cooling and moistening. Minimal fire activity was also observed during the Little Ice Age (0.7 – 0.25 ka BP). Fire frequencies increased during the interval from 1.7 to 0.7 ka BP and appears to be partly synchronous with climate warming during the Medieval Climate Anomaly. Regional reconstructions of long-term fire history show that recent fires are unprecedented during the late Holocene, with modern high biomass burning lying outside millennial and centennial variability of the last 3400 years.

Remote spatial analysis lacking ethnographic grounding mischaracterizes sustainability of Indigenous burning regime

Scientific research that purports to evaluate Indigenous fire regimes in the absence of ethnographically contextualized ecological data runs the risk of exacerbating the fire blame game and providing evidence to support distorted narratives advanced by anti-Indigenous advocates. Spatial analysis of fire scars in Indigenous territories can be an effective tool for characterizing cultural fire regimes in terms of distribution and frequency, especially when qualified by linkages to different local ecosystems. A recently published article drew on fire scar mapping from satellite imagery to assess anthropogenic fire distribution and frequency in the Pimentel Barbosa Indigenous Land, Central Brazil. The authors use their findings to characterize A'uwẽ (Xavante) use of fire as unmanaged and a model of unsustainable use of cerrado resources. In this article, we discuss Aguiar & Martins's recent paper in light of our long-term research on A'uwẽ hunting with fire in the Pimentel Barbosa Indigenous Land, arguing that A'uwẽ hunters do burn according to established cultural protocols, manage their use of fire for conservationist purposes, and do not cause environmental degradation by burning.

Factors contributory to fire occurrences in two populated areas in the American southwest

PurposeThis study aims to further understand the factors contributory to fire occurrences in two semi-arid regions in the American Southwest, Clark County in Nevada and Maricopa and Pinal Counties in Arizona.Design/methodology/approachStatistical and geographic information system analyses were employed to examine the spatial and temporal relationships of various natural and human-caused factors with fire incidences.FindingsAngström fire danger index, average amount of rainfall one month prior, extent of forests and grasslands, and proximities to secondary roads and population centers have significant relationships with fire events.Research limitations/implicationsThe importance of the factors contributory to fire occurrence is site-specific even in areas with similar climatic regimes and varies among different geographic regions; as such, researchers will need to conduct specific investigation of each study area.Practical implicationsThe findings of this study can be instrumental in facilitating fire managers to derive more informed strategies in fire prevention and management.Originality/valueWhile there are many studies on fire, most of them are conducted in wet regions with a lot of vegetative cover; not much work is done on arid areas. This paper considered and compared the spatial and temporal relationships of a wide range of natural and human-caused factors with fire events in two semi-arid areas. The intent was to assess the relative importance of these factors in areas even with similar climatic regimes. As our world is facing unprecedented changes in terms of climate and population growth, it is paramount to have an enhanced understanding of the impacts of these changes on fire regimes. The study areas are hot and dry, and they are located in the wildland–urban interfaces with rapid population growth and urbanization; as such, the research findings may contribute to existing literature.

Mitigating post-fire regeneration failure in boreal landscapes with reforestation and variable retention harvesting: At what cost?

Successive disturbances such as fire can affect post-disturbance regeneration density, with documented adverse effects on subsequent stand productivity. We conducted a simulation study to assess the potential of reactive (reforestation) and proactive (variable retention harvesting) post-fire regeneration failure mitigation strategies in a 1.37-Mha fire-prone boreal landscape dominated by black spruce and jack pine. We quantified their respective capacity to maintain landscape productivity and post-fire resilience, as well as their associated financial returns under current and projected (RCP 8.5) fire regimes. While post-fire reforestation with jack pine revealed to be the most effective strategy to maintain potential production, associated costs quickly became prohibitive when applied over extensive areas. Proactive strategies such as an extensive use of variable retention harvesting, combined with replanting of fire-adapted jack pine only in easily accessible areas, appeared as a more promising approach. Despite this, our results suggest an inevitable erosion of forest productivity due to post-fire regeneration failure events, highlighting the importance to integrate fire a priori in strategic forest management planning as well as its effects on long-term regeneration dynamics.

Wildfire activity enhanced during phases of maximum orbital eccentricity and precessional forcing in the Early Jurassic

Fire regimes are changing due to both anthropogenic climatic drivers and vegetation management challenges, making it difficult to determine how climate alone might influence wildfire activity. Earth has been subject to natural-background climate variability throughout its past due to variations in Earth’s orbital parameters (Milkankovitch cycles), which provides an opportunity to assess climate-only driven variations in wildfire. Here we present a 350,000 yr long record of fossil charcoal from mid-latitude (~35°N) Jurassic sedimentary rocks. These results are coupled to estimates of variations in the hydrological cycle using clay mineral, palynofacies and elemental analyses, and lithological and biogeochemical signatures. We show that fire activity strongly increased during extreme seasonal contrast (monsoonal climate), which has been linked to maximal precessional forcing (boreal summer in perihelion) (21,000 yr cycles), and we hypothesize that long eccentricity modulation further enhances precession-forced fire activity.

Indigenous impacts on north Australian savanna fire regimes over the Holocene

Fire is an essential component of tropical savannas, driving key ecological feedbacks and functions. Indigenous manipulation of fire has been practiced for tens of millennia in Australian savannas, and there is a renewed interest in understanding the effects of anthropogenic burning on savanna systems. However, separating the impacts of natural and human fire regimes on millennial timescales remains difficult. Here we show using palynological and isotope geochemical proxy records from a rare permanent water body in Northern Australia that vegetation, climate, and fire dynamics were intimately linked over the early to mid-Holocene. As the El Niño/Southern Oscillation (ENSO) intensified during the late Holocene, a decoupling occurred between fire intensity and frequency, landscape vegetation, and the source of vegetation burnt. We infer from this decoupling, that indigenous fire management began or intensified at around 3 cal kyr BP, possibly as a response to ENSO related climate variability. Indigenous fire management reduced fire intensity and targeted understory tropical grasses, enabling woody thickening to continue in a drying climate.