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Congestion
Obstacles in the path of the flame that generate turbulence.
Consequence
The undesirable result of a loss event, usually measured in health and safety effects, environmental impacts, loss of property, and business interruption costs.
Consequence Analysis
The analysis of the expected effects of incident outcome cases, independent of frequency or probability.
Consequence Based Approach
The methodology used for building siting evaluation that is based on consideration of the impact of explosion, fire and toxic material release which does not consider the frequency of events.
Conservation Vent Valve
A device designed to maintain pressure within preset limits in a liquid-containing vessel for the purpose of emissions reduction. It also provides protection against excessive pressure or vacuum.
Contain and control measures
Primary containment system, basic process control system, operating procedures and training, and other measures to Keep process materials and energies confined within the primary containment system and to Keep the process within safe design and operating limits, thus avoiding abnormal situations and loss-of-containment events that could lead to loss, damage and injury impacts.
Containment
A system condition in which under no condition reactants or products are exchanged between the chemical system and its environment.
Containment Strategy
A generalized approach for limiting or eliminating exposure of personnel, products, or the environment to hazardous concentrations of substances.
Continuous Improvement
Doing better as a result of regular, consistent efforts rather than episodic or step-wise changes, producing tangible positive improvements either in performance, efficiency, or both. Continuous improvement efforts usually involve a formal evaluation of the status of an activity or management system, along with a comparison to an achievement goal. These evaluation and comparison activities occur much more frequently than formal audits.
Continuous Reactors
Reactors that are characterized by a continuous flow of reactants into and a continuous flow of products from the reaction system (e.g., Plug Flow Reactor (PFR) and the Continuous Stirred Tank Reactor (CSTR)).
Continuous Release
Emissions that are long in duration compared with the travel time (time for could to reach location of interest) or averaging or sampling time.
Contractor Management
CCPS RBPS Element 11: This Element ensures that contractor workers are vetted for their specialized services and can perform their work safely using facility standards.
Contractor management
A system of controls to ensure that contracted services support (1) safe facility operations and (2) the company's process safety and personal safety performance goals. It includes the selection, acquisition, use, and monitoring of contracted services.
Contributing Cause
Factors that facilitate the occurrence of an incident such as physical conditions and management practices. (Also known as contributory factors.)
Controlled Document
Documents covered under a revision control process to ensure that up-to-date documents are available and out-of-date documents are removed from circulation.
Controls
Engineered mechanisms and administrative policies/
Core value
A value that has been promoted to an ethical imperative, accompanied with a strong individual and group intolerance for poor performance or violations of standards for activities that impact the core value.
Corrective Maintenance
Maintenance performed to repair a detected fault.
Corrosive
A material that can attack and chemically destroy exposed body tissues, and can also damage or even destroy metal.
Corrosivity
A complex series of reactions between water and metal surfaces and materials in which the water is stored or transported.
Cost-Benefit Analysis (CBA)
Part of the management decision-making process in which the costs and benefits of each risk reduction option are compared and the most appropriate alternative is selected.
Countermeasure
An action taken or a physical capability provided whose principal purpose is to reduce or eliminate one or more vulnerabilities.
Covered Process
A process subject to regulatory requirements established under the OSHA PSM Standard or the EPA RMP Rule.
Critical
Relates to major environment or safety process risks.
Critical Alarm
An alarm having no automatic safety backup system and requiring immediate action to be taken by an operator to return the plant to a safe status (e.g., atmospheric combustible or toxic gas detection).
Critical Equipment
Equipment, instrumentation, controls, or systems whose malfunction or failure would likely result in a catastrophic release of highly hazardous chemicals, or whose proper operation is required to mitigate the consequences of such release. (Examples are most safety systems, such as area LEL monitors, fire protection systems such as deluge or underground systems, and key operational equipment usually handling high pressures or large volumes.)
Critical Infrastructure
Systems and assets, whether physical or virtual, so vital that the loss, interruption, incapacity, or destruction of which (1) would have a negative or debilitating effect on the security, economic security, public health, or safety of a nation, region, or any local government, or (2) cause national or regional catastrophic effects.
Critical Mass
Minimum mass that is required to enable the occurrence of an explosion.
Critical Operating Parameter
Process condition (e.g., flow rate, temperature) that can lead to an equipment failure if limits are exceeded.
Critical Temperature
Maximum cooling temperature at which all heat is generated by the mass of material can still be transferred to the coolant (either gas or liquid).
Cross-contamination
Mixing chemicals unintentionally, typically through the use of the same process equipment or support systems for concurrent or successive tolls.
Damage Limiting Construction
Construction of equipment (building) with weak sections to limit the damage to the equipment (building). The weak sections fail early and prevent damage to the rest of the equipment (building).
Damage/failure mechanism
The mechanical, chemical, physical, or other process that results in equipment deterioration.
De Minimis Risk
A level of risk that would be perceived by most to be broadly acceptable, and not requiring further reduction.
Deadheading
A blockage on the discharge side of an operating pump which results in the flow reducing to zero and an increase in the discharge pressure. The energy input from the deadheaded pump increases the temperature and pressure of the fluid in the pump.
Decision tree
A logic tree used in reliability-centered maintenance (RCM) to help determine the correct type of maintenance (e.g., predictive, preventive) to perform to reduce the likelihood of equipment failures.
Decommissioning
Completely de-inventorying all materials from a process unit and permanently removing the unit from service. Decommissioning normally involves permanently disconnecting the unit from other processes and utilities, and is often followed by removal of the process piping, equipment, and support structures.
Decomposition
Breakdown of a material or substance (by heat, chemical reaction, electrolysis, decay, or other processes) into parts or element or simpler compounds. Importance: Decomposition products often present different hazards than the original material.
Decomposition Energy
The maximum amount of energy which can be released upon decomposition. The product of decomposition energy and total mass is an important parameter for determining the effects of a sudden energy release, for example, in an explosion. The decomposition energy can occasionally be obtained from the literature or calculated theoretically. (Barton and Rogers 1997)
Decomposition Temperature
Temperature at which spontaneous decomposition occurs. In practice it is impossible to indicate the exact value of this temperature, because according to the Arrhenius law the reaction rate will only be zero at absolute zero temperature (0 K). Therefore, in measuring the decomposition temperature the sample quantity and the sensitivity of the measuring device is very important.
Deductive Approach
Reasoning from the general to the specific. By postulating that a system/process has failed in a certain way, an attempt is made to determine what modes of system/component/operator/organization behavior contributed to the failure.
Defensive Measures
Measures directed to reduce the consequences of a runaway to an acceptable level. The chemical reaction of a substance in which the reaction front advances into the unreacted substance at less than sonic velocity. Where a blast wave is produced that has the potential to cause damage, the term explosive deflagration may be used.
Deflagration
A combustion that propagates by heat and mass transfer through the un-reacted medium at a velocity less than the speed of sound.
Deflagration Flame Arrester
A flame arrester used to prevent the transmission of a deflagration.
Deflagration Index, (KSt Value)
The measure of the explosibility of a dust cloud, in units of bar-m/s.
Deflagration Isolation
A method employing equipment and procedures that interrupts the propagation of a deflagration flame front past a point (usually in a pipe).
Deflagration Pressure Containment:
The technique of specifying the design pressure of a vessel and its appurtenances so that they are capable of withstanding the maximum pressures resulting from an internal deflagration.
Deflagration Suppression
The technique of detecting and arresting combustion in a confined space while the combustion is still in its incipient stage, thus preventing the development of pressures that could result in an explosion.
Deflagration to Detonation Transition (DDT)
The transition phenomenon resulting from the acceleration of a deflagration flame to detonation via flame-generated turbulent flow and compressive heating effects. At the instant of transition a volume of pre-compressed, turbulent gas ahead of the flame front detonates at unusually high velocity and overpressure.
Deflagration Venting
The reduction of pressure generated in a vessel by a deflagration by allowing the emergency flow of the vessel contents from the vessel by means of an opening in the vessel, thus avoiding the failure of the vessel by overpressure. The vent opening is usually closed by a pressure-relieving cover (e.g., rupture disk, explosion disk or hatch).