Browsing by Author "Davis, Scott"
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Item Designing Effective Emergency Response Plans: Lessons learned from investigating two major incidents(Mary Kay O'Connor Process Safety Center, 2018) Davis, Scott; GexCon USEmergency response plans are an essential, yet oftentimes overlooked, layer of protection for facilities where all other layers of protection failed to prevent an incident. While catastrophic accidents such as large releases of chemicals, fires or explosions are devastating for the process industry, experience investigating numerous incidents has shown that a lack of an effective emergency response plan can lead to an unnecessary and tragic escalation of the incident. More specifically, investigation of two recent incidents: (1) 2015 explosion on the FPSO Cidade São Mateus and (2) 2013 West Texas Explosion; will demonstrate how the lack of emergency planning resulted in devastating consequences that could have been avoided with the proper planning. More specifically, the FPSO explosion resulted in 9 fatalities, eight of which were responding to a leak of condensate, and the Danvers explosion that resulted 15 fatalities, most of whom were responding to the fire that preceding the devastating explosion. Lessons will show that deficiencies in the emergency response plan or implementation of the plan resulted in these fatal consequences that could have been avoided. In addition, while emergency response plans consider “maximum credible” scenarios, past events have shown that low probability high consequences should also be at least considered. Advanced tools will be discussed that can assist an owner/operator prepare an effective emergency response plan.Item Is my facility at risk? Understanding the risks associated with low burning velocity compounds(Mary Kay O'Connor Process Safety Center, 2017) Pagliaro, John; Davis, Scott; van Wingerden, Kees; GexCon USA key factor when performing risk assessments and facility siting studies is to assess the explosion and flash fire risk of combustible fluids. There are accurate and established methods to do so when dealing with flammable fluids that have laminar burning velocities (LBVs) around 40 cm/s (e.g., most hydrocarbons). There is currently a need to establish equivalently accurate methods for mildly flammable fluids that have LBVs less than 10 cm/s (e.g., R-32 and ammonia). The use of such fluids is growing, particularly in the heating, ventilation, air conditioning, and refrigeration (HVAC&R) industries as the result of on-going efforts to phase out working fluids with high global warming potential. Without an accurate method of assessing the explosion and flash fire risk of mildly flammable fluids, a very conservative approach is often applied. The approach is to assume the explosion properties of mildly flammable fuels are close to those of methane when evaluating the potential explosion consequences. This will, however, grossly over-predict the potential explosion consequences as flame speed and overpressures during explosions and flash fires are directly correlated to the LBV of the fuel. Furthermore, the likelihood of an explosion or flash fire may also be overpredicted when assuming flammability properties are equivalent to those of methane. Therefore, it is important to not only understand the explosion consequences but also the likelihood of having an explosion, which includes the probability of flammable mixtures forming and subsequently being ignited. Flammability properties and characteristics of mildly flammable fluids must be thoroughly understood to accurately evaluate the probability and consequence of the fire/explosion hazards associated with their use. This study examines post-ignition consequences at large scales through experimentation and with computational fluid dynamics. Fundamental flammability properties of mildly flammable fluids are also measured and presented along with previously reported data in the literature to evaluate potential measurement uncertainties. The flammability properties are then discussed in the context of the likelihood of having an explosion or flash fire, specifically in regard to the probability of forming a flammable mixture and the probability of a flammablemixture being ignited. The combined large-scale consequence testing, fundamental flammability and ignitibility experiments, and modeling results will allow for more accurate assessments of risk.Item Large Scale Detonation Testing – RPSEA Project Award(Mary Kay O'Connor Process Safety Center, 2015) Davis, Scott; Engel, Derek; Wingerden, Kees van; GexCon USAs the size of Ultra Deep Water (UDW) facilities increases in the Gulf of Mexico (GOM), designs must consider the potential adverse effects associated with vapor cloud explosions in large congested areas and understand the potential for more devastating deflagration-to- detonation transitions (DDTs) on these facilities. However, there is a lack of data at the large scale to validate the necessary design tools used to predict the risk of DDT. GexCon was awarded Subcontract 12121-6403-01 under the Research Partnership to Secure Energy for America (RPSEA), whereby the objective of this project is to improve inherently safer offshore facility designs. One of the main goals of this research project is to provide large scale DDT explosion data and validate the tools necessary to predict vapor cloud explosions in early design phase. The work will also be used to develop guidance documents and recommended practices to facility owners and designers in order to minimize the potential consequence of explosion incidents. This paper will present the current updates for the large scale testing being conducted in a newly developed test rig of 51,840 ft3 (1,459 m3 ) gross volume. These tests will involve evaluation of deflagrations and DDTs involving stoichiometric, lean and rich mixtures ethylene, propane and methane. Further phases of the testing will evaluate the effectiveness of other mitigation measures (e.g., water deluge, solid inhibitor) on the explosion consequences. These experiments will be used to validate and further develop industry-accepted CFD tools and more simplified methods in their prediction of DDTs at the large scale including events involving mitigation.Item Large Scale Detonation Testing: New Findings in the prediction of DDTs at large scales(Mary Kay O'Connor Process Safety Center, 2016) Davis, Scott; Merilo, Erik; Engel, Derek; Wingerden, Kees van; Gexcon US; SRI InternationalA large vapor cloud explosion (VCE) followed by a fire is one of the most dangerous and high-consequence events that can occur at petrochemical facilities. As the size and complexity of facilities increase, designs must consider the potential adverse effects associated with vapor cloud explosions in large congested areas and understand the potential for more devastating deflagration-to-detonation transitions (DDTs) on these facilities. While the likelihood of DDTs is lower than deflagrations, they have been identified in some of the most recent large-scale explosion incidents including: 2005 Buncefield explosion, 2009 San Juan explosion, and 2009 Jaipur event. The consequences of DDTs can be orders of magnitude larger than deflagration because they have the ability to self-propagate outside the region of high congestion/confinement. Hence, it is critical to understand how a facility’s geometry or equipment layout can affect explosion consequences and assist in their mitigation and/or prevention. Due to the inability to predict such devastating phenomena on the large scale, owners and designers cannot evaluate installations for risk of DDTs and provide “inherently safer” layout or mitigation measures to significantly reduce or eliminate such hazards. However, there is a lack of data at the large scale to validate the necessary design tools used to predict the risk of DDT. One of the main goals of this research project is to provide large scale DDT explosion data and validate the tools necessary to predict vapor cloud explosions in early design phase. This paper will present the results of large scale testing being conducted in a newly developed test rig of 50,000 ft3 (1,500 m3 ) gross volume under award Subcontract 12121-6403-01 provided by the Research Partnership to Secure Energy for America (RPSEA). These tests involve evaluation of deflagrations and DDTs involving stoichiometric, lean and rich mixtures, with propane and methane fuels. The effectiveness of mitigation techniques such as solid inhibitors or deluge is evaluated for preventing DDTs.Item Maximizing the Benefit of Early-Stage CFD Ventilation Analyses to Reduce Fire and Explosion Hazards(Mary Kay O'Connor Process Safety Center, 2016) Botwinick, Drew; Quilliou, Josue; Davis, Scott; Gexcon USOne of the most significant hazards faced by offshore platforms, FLNGs, and chemical facilities is the risk of explosions resulting from the ignition of flammable clouds due to an unintentional release (leak). Natural ventilation can act as a passive safety measure by helping to dilute and disperse released gases to levels below their flammable limits. Computational fluid dynamics (CFD) ventilation studies are often performed to validate that layouts meet industry criteria or as a step in more complex safety studies; however, often these studies occur during later phases of design after it is “too late” to make basic changes that can drastically alter the risk posed by toxic, fire, and explosion hazards. Many ventilation studies provide results as a single measure, such as “adequate ventilation” measured by the number of air changes per hour (ACH) for a given area. For example, certain hazardous area classifications require that the ventilation must be greater than 12 ACH at least 95% percent of the time (95th percentile ACH). However, the 95th percentile ACH only describes a limited range of the ventilation conditions at the facility and should not be used as the sole means of comparing alternative layouts or making design decisions. A carefully constructed ventilation study that accounts for the nature of facility hazards can provide relatively fast and inexpensive insight into potential safety-oriented optimizations during early stages of facility design. By providing this insight early in design, facilities can be rigorously designed for safety—minimizing the risk (and therefore cost) of late-stage design changes. This paper will present guidance on some of the requirements for and benefits of early-stage ventilation studies. The paper will use specific examples derived from recent work in prioritizing safety in early-stages of design to demonstrate the value of such studies and why the industry needs to move beyond focusing on just the 95th percentile ACH.Item Molecular genetics of bovine 70 kilodalton heat shock protein (HSP70) genes(1992) Grosz, Michael David; Skow, Loren; Davis, Scott; Peterson, David; Womack, JamesSequences homologous to a 2.3 kilobase (kb) human HSP70 cDNA were extracted from a bovine sperm DNA library. The cloned DNA was restriction mapped and sequences containing HSP70 coding regions, along with those sequences containing unique, flanking DNA, were subcloned into plasmid vectors. Unique, flanking DNA fragments were used as locus-specific probes to identify the chromosomal location of the bovine HSP70 genes. DNA fragments containing HSP70 coding regions were sequenced using the dideoxy DNA sequencing procedure. Twenty-one positive clones were obtained and isolated for analysis. Based on restriction map data, the 21 clones can be categorized into 12 identical clone classes. Consolidating overlapping classes yields 3 regions of DNA containing 4 bovine HSP70 genes. Locus-specific probes were hybridized to bovine-rodent somatic cell hybrid panels to identify the chromosomal locations of the 3 regions of DNA containing HSP70 sequences. One region contains 2 tandemly arrayed genes (HSP70-1 and HSP70-2), and exists on chromosome 23, syntenic with BoLA, the bovine major histocompatibility complex (MHC). Single HSP70 sequences, designated HSP70-3 and HSP70-4, were found in two other genomic regions. Analysis of restriction enzyme digested bovine DNA has revealed at least 4 HSP70 restriction fragment length polymorphisms (RFLPs). By hybridizing the locus-specific probes to restriction enzyme digested bovine DNA and other methods, individual RFLPs have been assigned to the HSP70 genes isolated from the library. By combining three RFLPs which exist within a stretch of 20 kb (syntenic with bovine major histocompatibility complex), a highly polymorphic haplotype can be determined for each animal. This haplotype can be used as a marker in future linkage analyses involving the structure and gene order of the bovine MHC, as well as other loci on chromosome 23. Data obtained from DNA sequencing indicates that the four HSP70 sequences are highly conserved at both the nucleotide and presumed amino acid level. The addition of these loci to the bovine gene map further defines three regions of syntenic conservation between bovine and human genomes.Item Quantitative trait loci and somatostatin(United States. Patent and Trademark Office, 2009-09-08) Cai, Li; Taylor, Jeremy; Smyth, Kerrie-Ann; Findeisen, Brian; Lehn, Cathi; Davis, Sara; Davis, Scott; The Texas A & M University SystemThe disclosure relates to the use of genetic traits in livestock for determining breeding characteristics of livestock progeny, and for optimizing the management and marketing of livestock for improving feedlot performance and meat quality. The disclosure specifically relates to genetic markers and single nucleotide polymorphisms (SNPs) in the bovine somatostatin locus, as well as haplotypes that include the somatostatin locus, which are associated with certain quantitative trait loci (QTLs), such as marbling, meat quality grade, and yield grade. In a preferred embodiment, the SNPs and haplotypes are predictive of the increased or decreased amount of tissue marbling in the animal.