White Papers

Quantify Explosion Venting Dynamics in Vessels, Enclosures, and Energy Storage Systems

Explosions can occur in vessels or enclosures containing flammable gases and/or dusts. Explosion venting, often referred to as deflagration venting (because we cannot practically vent detonations), is used to protect from catastrophic vessel/enclosure failure. Simplified equations are often used to determine the deflagration relief requirements. Simplified equations can be found in standards such as NFPA-68. While easy to use, simplified equations tend to overestimate the relief requirements and have several practical limitations. Simplified equations provided in NFPA-68 [1] require the use of an explosion severity index, usually obtained from actual testing in a 20 liter sphere or a 1 m3 vessel. Published severity index data for flammable gases or dusts are also used. Typically, simplified equations for deflagration venting apply to ideal geometries and for short vent lines. They are not readily applicable to complex geometries, systems with elevated initial temperatures or pressures, hybrid systems containing flammable gases and dusts, systems with diluents and/or chemical oxidizers, systems with reduced venting set pressures, geometries with long L/D ratios or geometries with long vent piping where flame acceleration becomes significant. We have developed detailed deflagration and explosion dynamics methods and computer codes that address many of the shortcomings of simplified sizing methods. These dynamic methods rely on a detailed representation of all possible independent combustion reaction(s) using direct Gibbs free energy minimization [2, 3, 4] coupled with a detailed burning rate model developed from measured explosion data using a 20 liter sphere or a 1 m3 vessel. We describe these methods in what follows and provide examples of how they are applied and how the burning rate models are developed from measured data. Read more

Quickly Develop Chemical Interaction Matrices with SuperChems™

The development of accurate chemical interaction matrices can provide valuable information for the management of potential chemical reactivity hazards. SuperChems™, a component of Process Safety Office®, provides intuitive and easy to use utilities for the rapid development of chemical interaction matrices. These utilities were developed based on known heuristics and rules for the interaction of certain chemical groupings. SuperChems™ also provides additional utilities for the calculation of energy release and stoichiometry of one or more chemical reactions using detailed multiphase chemical equilibrium algorithms and reacting flow dynamics. In addition to thermo-physical and transport properties databanks, SuperChems™ provides hazards databanks where chemical groupings and other reactivity and toxicity data are available for approximately three thousand chemicals. Of particular interest is version 8.5 of the hazards databanks, released in March of 2018. Read more

Reactive Chemical Storage

It is a common practice to insulate storage tanks containing reactive chemicals to protect against fire exposure. While this mitigation technique is appropriate for vessels handling non-reactive chemicals, reactive chemicals storage represents a special challenge and must be examined on a case-by-case basis. Read more

Reactivity Screening Made Easy

During the past decade, large efforts were made by the US chemical and petrochemical industries to implement and maintain effective process safety management (PSM) and responsible care programs. Despite these large investments, incidents continue to occur at an alarming frequency. Many executives of leading companies are trying to understand why. A recent survey conducted by the US Chemical and Safety Hazard Investigation Board (CSB) concluded that reactive chemicals present a significant safety problem for the chemical process industries. Key root causes identified by the CSB survey included technical and management systems failures. This underscores the importance of the need to understand and manage chemical reaction hazards more effectively. We also believe that the “quality” of implementation, change management, and auditing of corporate PSM programs is the culprit. We focus in this short paper on incidents caused by runaway reactions and provide guidance on how to improve the “Quality” of managing chemical reactions hazards through a combination of screening and experimental tools. Read more

SADT Determination of Styrene System Using ARC

The United States Department of Transportation (US DOT) and United Nations (UN) have developed a transport systemization based on a classification of certain types of dangerous goods and descriptions of tests and procedures. Dangerous goods are chemical substances, or articles containing chemical substances, which pose a threat to public safety or the environment during transportation if not properly identified or packaged. If they are accidently released, outcomes such as fires or explosions can occur. The purpose of the various tests is to provide adequate protection against the risk to life and property inherent in the transportation of hazardous materials in commerce. Read more

The Role of Chemical Reactivity Data in Process Safety Management

Chemical reactivity is addressed throughout the requirements of OSHA’s PSM Standard. It is specifically required in the process safety information element. In addition, it is necessary input to process hazard analysis, operating procedure development, emergency relief system design, and mechanical integrity. As the understanding of the impact of chemical reactivity hazards on the operation of a chemical process continues to develop, it is important to have a method for developing this data. Equally important is a method for extracting meaningful reactivity information from the data and incorporating it into process safety. This paper will present a process for evaluating chemical reactivity hazards using an Accelerating Rate Calorimeter (ARC®). It will then explain how to extract information from this data to help define process safety elements such as safe upper and lower limits, emergency relief system design, etc. Read more