An Overview of Vapor Cloud Explosions and Their Relationship to Equipment and Piping Configurations

2002 ◽  
Author(s):  
Adrian J. Pierorazio
Keyword(s):  
Pressure Vessel ◽  
Process Equipment ◽  
Equipment Failure ◽  
Construction Costs ◽  
Free Expansion ◽  
Vapor Cloud

Pressure vessel and piping layout is usually focused on minimizing construction costs and ensuring safety from an equipment failure standpoint. When the equipment contains flammable gases, a leak or rupture may result in a vapor cloud explosion (VCE). The severity of the resulting explosion is a function of the material reactivity, the equipment density, and the presence of structures that restrict the free expansion of the combusting cloud. This paper provides an overview of existing vapor cloud explosion prediction methodologies, with an emphasis on the effects of process equipment and piping spacing on the severity of a VCE.

scholarly journals Modeling the Consequences of Methane Gas Expansion in a CNG Fuel Stations of Isfahan Province

2021 ◽  
Author(s):  
Mahdieh RASTIMEHR ◽  
Mahshid BAHRAMI ◽  
Adel MAZLOMI ◽  
Mohammad Hossein CHALAK ◽  
Reza POURBABAKI
Keyword(s):  
Natural Gas ◽  
Thermal Radiation ◽  
Design Process ◽  
Pressure Vessel ◽  
Safe Distance ◽  
Compressed Natural Gas ◽  
Isfahan Province ◽  
Vapor Cloud ◽  
Fire And Explosion ◽  
Gas Expansion

Introduction: Assessment of the consequences of hazards such as fire and explosion is one of the most urgent and important steps to improve the level of safety in the current stations and those that are in the design process. The purpose of this study was to review the model of CNG Compressed Natural Gas releases and the range of damages to individuals and equipment. Moreover, we examined the observance of safe distance of this station to its surroundings. Materials and Methods: In this study, modeling the effects of fire and explosion on the CNG fuel station in Isfahan province was performed using ALOHA software. In this model, six scenarios were designed to create a hole with a diameter of 0.03m and a gap of 0.2m and width of 0.2 m in a pressure vessel. Results: It was observed that the toxic atmosphere was within the distance of 55 meters at a concentration of 65000 ppm. In the case of a gap, the toxic vapor cloud range could increase to 66 meters. The flammable superpower range was 89meters for the hole but 107 meters for the gap. The thermal radiation from the jet fire to the distance of 25meters was 10 kw/sqm for the hole, but the thermal radiation was 10 kw/sqm for the gap to 35meters. Conclusion: The most dangerous scenario was the Jet Fire, which involved not only the CNG station, but also the municipal parking area. Furthermore,  the thermal radiation produced by the gap was greater than the hole with regard to the involved range.  

Use of API 579-1/ASME FFS-1 Limit-Load Criteria for Establishing Load Limits for Pressure Vessel Internals

2010 ◽  
Author(s):  
Brian R. Macejko
Keyword(s):  
Closed Form ◽  
Pressure Vessel ◽  
Limit Load ◽  
Process Equipment ◽  
Maximum Pressure ◽  
Plastic Collapse ◽  
Closed Form Solutions ◽  
Perfectly Plastic ◽  
Section Viii ◽  
Elastic Perfectly Plastic

The 2007 edition of ASME Boiler & Pressure Vessel Code Section VIII Division 2 and the 2007 edition of Fitness-For-Service API 579-1/ASME FFS-1 provide the option to use the limit-load method to assess protection against plastic collapse for components of pressurized process equipment. Per the methodology presented therein, the allowable load on a component is established by applying design factors to the elastic-perfectly plastic limit-load such that the onset of gross plastic deformation (plastic collapse) will not occur. Typically, the design limitations of pressure vessel internal components have been assessed through closed form solutions with conservative assumptions. It has been found that the maximum pressure delta across vessel internals established through closed form solutions can become limiting in determination of time between equipment shutdowns. This paper will outline a practical example of industry applied use of the limit-load method to qualify extended limits on mechanical loads applied to pressure vessel internals.

Review of Ultrasonic Phased Arrays for Pressure Vessel and Pipeline Weld Inspections

2005 ◽  
Vol 127 (3) ◽  
pp. 351-356 ◽  
Author(s):  
Michael Moles ◽  
Noël Dubé ◽  
Simon Labbé ◽  
Ed Ginzel
Keyword(s):  
Pressure Vessel ◽  
Phased Array ◽  
Beam Steering ◽  
Ultrasonic Inspection ◽  
Time Data ◽  
Construction Costs ◽  
Array Technology ◽  
Weld Profile ◽  
Asme Code ◽  
Pulse Echo

Major improvements in weld inspection are obtained using Phased Array technology with capability for beam steering, electronic scanning, focusing, and sweeping the ultrasonic beams. Electronic scanning is much faster than raster scanning, and can optimize angles and focusing to maximize defect detection. Pressure vessel (PV) inspections typically use “top, side, end” or “top, side, TOFD” views, though other imaging is possible. Special inspections can be performed, e.g., for specific defects, or increased coverage. Defects can be sized by pulse-echo as per code, by time-of-flight Diffraction or by back diffraction. New PV inspection codes, particularly ASME Code Case 2235, permit the use of advanced ultrasonic inspection techniques. Pipeline girth weld inspections use a unique inspection approach called “zone discrimination,” and have their own series of codes. While similar equipment is used in pipeline as in PV inspections, the pipeline philosophy is to tailor the inspection to the weld profile and predicted lack of fusion defects. Pipeline displays are specifically designed for near real-time data analysis. Both ASME CC 2235 and the pipeline codes permit the use of Fitness-For-Purpose, which reduces construction costs. Overall, phased array systems meet or exceed all PV and pipeline codes.

The Consequence Analysis of Pressure Vessel Failure

2011 ◽  
Vol 396-398 ◽  
pp. 66-70
Author(s):  
Zhi Xiang Xing ◽  
Xian Jin Wang
Keyword(s):  
Pressure Vessel ◽  
Toxic Substance ◽  
Gas Mixture ◽  
Chemical Burns ◽  
Software Simulation ◽  
Consequence Analysis ◽  
A Value ◽  
Surrounding Environment ◽  
Vapor Cloud ◽  
Process Plants

After a chemical vessel suffering a rupture, BLEVE, fireball, jet fire, and dispersion of toxic substance may be the most common failure ways. Which give rise to a great threat to people’s life, process plants and surrounding environment. This paper presents an overview of the mechanism and the consequences for these failures; finally, ALOHA software simulation resorted to evaluating the consequences for all kinds of hazard, a vertical tank with the size of diameter=10, tank length=20m, containing the propane liquid/gas mixture with a volume of 1571 cubic meters, the mass of the chemical is calculated by the software automatically with a value of 554 tons. All the possible failures have been simulated by the ALOHA software, including：1) leaking tank, chemical is not burning as in escapes into the atmosphere; 2) leaking tank, chemical is burning as a jet fire; and 3) BLEVE, tank explodes and chemical burns in a fireball. Furthermore, there are three types hazard available to analyze the situation that chemical is not burning as it escapes into the atmosphere, they are: a) toxic area of vapor cloud; b) flammable area of vapor cloud; and c) blast area of vapor cloud explosion. The result reveals that the farthest threat zone reaches 2.2km in the case of a fireball triggered by a BLEVE, and the result has been viewed and discussed in details.

Update of CCPS book “guidelines to evaluating vapor cloud explosion, pressure vessel burst, BLEVE and flash fire hazards”

2011 ◽  
Vol 30 (3) ◽  
pp. 296-300 ◽  
Author(s):  
Quentin A. Baker ◽  
Adrian J. Pierorazio ◽  
John L. Woodward ◽  
Ming Jun Tang
Keyword(s):  
Pressure Vessel ◽  
Fire Hazards ◽  
Explosion Pressure ◽  
Flash Fire ◽  
Vapor Cloud
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