Physical processing chemical reactivity hazard

Passive controls, process controls, 97-98 Paterson, New Jersey incident, 160-161 Peroxide formers, screening methods, 46-48 Physical processing chemical reactivity hazard, 8-10,11 screening methods, 36, 41—42 worked examples, 128,129 Polymerizing compounds, screening methods, 55... 

Introduction Chemical reactivity is the tendency of substances to undergo chemical change. A chemical reactivity hazard is a situation with the potential for an uncontrolled chemical reaction that can result directly or indirectly in serious harm to people, property, or the environment. A chemical reaction can get out of control whenever the reaction environment is not able to safely absorb the energy and products released by the reaction. The possibility of such situations should be anticipated not only in the reaction step of chemical processes but also in storage, mixing, physical processing, purification, waste treatment, environmental control systems, and any other areas where reactive materials are handled or reactive interactions are possible. 

Up to this point, the chemical reactivity hazards of individual substances, either by themselves or in contact with common environmental materials, have been considered. This last question in the chemical reactivity hazards screening will address the potential for an unintended chemical reaction due to incompatible materials contacting each other. Compatibility, in this context, means the ability of materials to exist in contact without specified (usually hazardous) consequences under a defined scenario. A scenario, in this context, is a detailed physical description of the process whereby a potential inadvertent combination of materials may occur (ASTM E 2012-00). 

Physical or chemical processes involving chemical reactivity hazards require carefully determined, facility-specific operating limits, which may go well beyond temperature control. Limits may need to be specified for addition quantities, rates and sequences agitation pH conductivity concentration pressure and other variables that either keep an undesired chemical reaction from starting or control a desired chemical reaction. Determination of these limits is outside the scope of this publication references such as Barton and Rogers (1997), CCPS (1995a) and HSE (2000) can be consulted for further information. 

In a Downstream Decomposing facility not the subject of this example, intentional chemistry is performed as ammonium dichromate is heated to decomposition to make chromium dioxide, which is used in the production of magnetic tape products. In the Upstream Feeds facility under study, physical processing is performed as ammonium dichromate is fed through a screw conveyor. The Preliminary Screening Method is to be used as a first-cut determination whether chemical reactivity hazards will need to be managed in the physical processing facility. 

Materials information includes toxicity, permissible exposure limits, physical properties, reactivity, corrosivity, thermal and chemical and hazardous effects of inadvertent mixing of different materials.Process information consists of 1) process flow diagrams, 2) process chemistry descriptions, 3) maximum amounts of chemicals, 4) safe ranges for temperatures, pressures, flows oi 5) evaluation of the con.sequences of deviations. 

Step 1—List Chemicals and Hazards The inherent physical properties (e.g., toxicity, flarmnabihty, reactivity) of a hazardous material in transit should be used to develop a list of chemicals that will be carried forward in the prioritization process. This list of chemicals may be different than that developed for accidental releases and may need to consider the following security issues ... 

The production of the process industry often involves hazards. Their nature can be both physical and chemical. Physical hazards derive from operating conditions which may be extreme, such as very low or very high temperatures and pressures. Chemical hazards are those associated with the materials present in the process, which can be toxic, flammable, explosible, or release energy due to spontaneous reactions. Indeed, it is the necessity to put the substances into a reactive state in order to enable one to produce the desired products that may lead to hazards. 

Information about the process must include the information required by the OSH A rule to include data on the chemistry and chemical hazards, the process methodology, and the process equipment. This includes chemistry and chemical hazards information to include physical data, toxicity, permissible exposure limits (PELs), reactivity data, thermal and chemical stability, hazardous effects of mixing with other chemicals, and corrosivity data. 

Stabilization means the conversion of a waste from its original form to a physically and chemically more stable material that is less likely to cause problems during handling and disposal, and less likely to be mobile after disposal. Stabilization can include chemical reactions that generate products that are less volatile, soluble, and reactive. Solidification, which is discussed below, is one of the most common means of stabilization. Stabilization is required for land disposal of wastes. Fixation is a process that binds a hazardous waste in a less mobile and less toxic form it means much the same thing as stabilization. 

Information pertaining to the hazards of the chemicals used in the process. This should contain at least the following information toxicity, flammability, permissible exposure limits, physical data, reactivity data, corrosivity data, thermal and chemical stability data, and hazardous effects of inadvertent mixing of different materials that could occur. 

Table 2 lists some of the physical, toxicity, flammability, and reactivity properties of common chemicals (10,13,42,45—51). Also given are some of the quantities specified for reporting spills and for compliance with legislated requirements. The OSHA regulations require that material safety data sheets (MSDS) be developed for all process materials, so that the hazard data can be communicated to employees (52). Characteristics of toxicity, flammability, chemical instability, reactivity and reaction energy, operating conditions, and corrosive properties of construction materials must all be considered in analyzing hazard potentials of chemicals and chemical operations. 

One of the functions of Global Core Technologies R D is the analytical discipline Reactive Chemicals/ Thermal Analysis/Physical Properties (RC/TA/PP). Some of the capabilities of this discipline are testing and data interpretation for reactive chemicals hazard assessment. It is the responsibility of the owner of any chemical process to use this Dow resource to obtain the information which is necessary to design a safe and efficient operation. Information about the analytical RC Testing discipline including contact names can be obtained on the INTRAnet at Reactive Chemicals/Thermal Analysis/Physical Properties web site. 

Physical hazards include noise, vibration, extremes of temperature, compressed gases, combustible and flammable chemicals, pyrophorics, explosives, oxidizers, and reactive materials. Process employees are exposed to physical hazards on a daily basis because they woric outside on the unit among pipes containing compressed gases, fluids under high temperatures, and flammable and explosive chemicals. Examples of some these hazards on a process unit might include ... 

Process Safety Information The standard requires application of certain steps and methods. The first step is compiling written process safety information. Information on the hazards of a highly hazardous chemical must address toxicity, PELs, physical data, reactivity data, corrosivity data, and thermal and chemical stabUity data. 

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