Process hazards pressure

Close proximity of hazardous process. High pressure vessels which may fail explosively. 

Complete and accurate written documentation of chemicals properties, process teclinology, and process equipment is essential to the PSM program and to a process hazards analysis (PrHA). This information serves many users including the PrHA team. The needed chemical information includes fire and explosion characteristics, reactivity hazards, safety and health hazards and the corrosion and erosion effects. Current material safety data sheet (MSDS ) information helps meet this requirement, but must be supplemented with process chemistry information regarding runaway reactions, and over-pressure hazards. 

Pressure rupture, 46, 47, 49, 57, 219 Pressure System Safety Regulations 2000, 423 Pressure systems, 17, 423 Process design, 135, 244, 397 Process hazards, 45, 243, 398 Protective clothing, 437... 

Control of the process. Prevention of hazardous deviations in process variables (pressure, temperature, flow), by provision of automatic control systems, interlocks, alarms, trips together with good operating practices and management. 

Examine all process parameters. Parameters (e.g., pressure, temperature, flow rate, level, pH) that are controlled or measured in a process are good indicators of possible process hazards. Process parameters should be examined for all modes of operation, independent of process chemicals, because some hazards exist that do not involve the chemicals. For example, if a process uses high-pressure steam, then both thermal energy and pressure-volume energy hazards exist even though steam is non-toxic, non-flammable, and non-reactive with most materials. 

The Reactive System Screening Tool (RSST), marketed by Fauske and Associates, is a relatively new type of apparatus for process hazard calorimetry [192, 196-198]. The equipment is designed to determine the potential for runaway reactions and to determine the (quasi) adiabatic rates of temperature and pressure rise during a runaway as a function of the process, vessel, and other parameters. 

During the development of a new facility or process, or when introducing a new process into an existing facility for the first time, an inherent safety review can be conducted to understand the chemical reactivity hazards and explore hazard reduction alternatives. The review need not be limited to chemical reactivity hazards. It can be used to address all other types of process hazards at the same time, including flammability/ combustibility dust or mist explosibility elevated or reduced pressures or temperatures phase differences and health hazards such as toxicity, corrosivity, and asphyxiation. 

Piping and Instrumentation Diagram Probability of Failure on Demand Process Hazard Analysis Pressure Indicator Protection Layer Preventive Maintenance Process Safety Incident Database Process Safety Management Pressure Safety Valve (Relief Valve)... 

Identifying the potential hazards (PHA, process hazard analysis, or HAZOP, hazard and operability analysis) during operation must be done from a wide-angle approach dangerous situations can occur due to many root-cause situations other than those specified by, for instance, ASME or PED. Based on the results of the risk assessment, the pressure equipment can be correctly designed and the most effective safety system selected. 

It has been found that the What-If style of process hazard analysis is a convenient method to use for a "simple" facility. For simple facilities, the detailed HAZOP approach has been found to be tedious and just as productive as a What-If method. The What-If approach stimulates generation of new ideas and discussion to cover issues associated with the items under review, as well as addressing generic issues. The specific HAZOP review is not necessary when the process is simple and well understood by the reviewing team. The team can readily review the major items of concern by asking What-If questions such as what happens when a pump fails, without relying on itemized and detailed variations of a process condition by the HAZOP method, such as high level, low pressure, etc. 

The regulation requires that new facilities conduct a process hazards analysis (PHA). The PSSR team should check that the PHA was, in fact, carried out, and that its recommendations were either resolved or implemented. During the pressure of construction, there is sometimes a tendency to postpone some of the PHA recommendations until there is sufficient time. The PSSR should check that the recommendations have, in fact, been closed out properly. 

The process hazards analysis for this vessel stated that either high temperature or high pressure is an indication of a potential runaway reaction that may result in an explosion. The safety requirements specification states that the SIF shall be SIL 2 and a nuisance or spurious trip should be better than one in every five years. The process will be operated for mission time of ten years after which a major overhaul and rebuild will take place. 

In general one supposes that the hazard potential of endothermic processes is small compared with that of exothermic ones. However, it must be checked whether one is dealing with a process capable of generating gas. If there is not suflftcient relief of the gas a hazardous pressure build-up may result [14]. 

The next two sections discuss protection against process hazards that are peculiar to chlorine processing. Section 9.1.10 covers emergency pressure relief both before and after the compressors. An important part of the discussion covers the design and operation of vent scrubbers to prevent the release of chlorine to the environment. Section 9.1.11 is dedicated to the explosion hazards presented by hydrogen and nitrogen trichloride. The sources of NCI3 are discussed, as well as its fate in the process. This includes the mechanisms of accumulation and safe decomposition. 

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