Process safety analysis parameters

Process safety refers to the application of engineering, science, and human factors to the design and operation of chemical processes and systems. The primary purpose of process safety is to prevent injuries, fatalities, fires, explosions, and unexpected releases of hazardous materials. Process safety focuses on the individual chemical processes and operational procedures associated with these systems. A process safety analysis is used to establish safe operating parameters, instrument interlocks, alarms, process design, and start-up, shutdown, and emergency procedures. Process safety programs cannot completely eliminate risk they can only control or reduce those risks. 

Computerized data management systems have the capability to automatically construct data reports for process safety data analysis once the report parameters are defined. 

The mass flow rate to be discharged following malfunctions depends on the process parameters, the nature of the malfunction and the pertinent boundary conditions. It is useful to determine these by a systematic safety analysis, for example a HAZOP study (vid. Sect. 9.1.2.3). In such an analysis special attention should be paid to identifying sequences leading to overpressure. Basically the following causes of overpressure can be distinguished (cf. [8]) ... 

The basis for the safety analysis of a plant is its P I diagram and a detailed description of the process. The plant is contemplated pipe by pipe. In each pipe the guidewords are applied to process parameters such as mass flow, pressure, temperature and concentration. Possible causes and consequences of deviations analyzed by thought experiments are identified. This enables one to decide on the necessity and type of possibly required countermeasures. The process of analysis may be supported by estimates of the frequency of occurrence of deviations and the extent of the accompanying consequences. 

Constraint 2 Safety considerations Polymerizations are exothermic processes that can cause runaways, so the maximum amounts of the monomer that can be present in the reactor should be limited for safety reasons. Therefore, to design safe processes an analysis of the risk parameters must be made in order to obtain the limits in reaction conditions for safe operation namely, the limits in monomer concentration and temperature that ensure that the pressure buildup in the reactor will not exceed the maximum pressure that the reactor can withstand. The risk parameters are the onset temperature, the adiabatic temperature increase, and the maximum temperature and pressure that may be reached during a polymerization... 

A. 1704. The safety limits for important process variables or parameters shall be stated and justified by the analyses provided in the SAR. Safety limits normally involve operational parameters such as fuel and fuel cladding temperatures, reactor coolant temperature, reactor pressure, reactor power, coolant flow rates and, for pool reactors, the water level above the core. These safety limits are derived primarily from Chapters A.5 (Reactor) and A. 16 (Safety Analysis). 

FMEA was originally developed by the US department of defence for military purposes today it is one of the first choices for performing a system safety analysis. It shall be mentioned that, apart from this System FMEA, there are also variants for process improvement called Process FMEA. According to the system structure, all components are analysed with respect to possible failures, and - similar to the HAZOP study - causes, consequences, and detection as well as risk mitigation measures are analysed and improvements proposed. Unlike the HAZOP, however, FMEA uses neither parameters nor guidewords but relies on the expertise and creativity of the analysis team to discover all potential failure modes of the system components. 

The control systans maintain process variables within the limits assnmed in the safety analysis for the plant. For the assumptions made in the safety analysis to remain vahd, certain parameters must be held within limits for the initial conditions of an anticipated operational occurrence or a design basis accident. The probability that the parameters of concern remain within these specified limits depends on the rehabihty of the control systans that maintain the parameters, and on the reliability of the instrnmentalion systems that monitor these parameters and annunciate any deviations to the operator for corrective actions. 

For the determination of reaction parameters, as well as for the assessment of thermal safety, several thermokinetic methods have been developed such as differential scanning calorimetry (DSC), differential thermal analysis (DTA), accelerating rate calorimetry (ARC) and reaction calorimetry. Here, the discussion will be restricted to reaction calorimeters which resemble the later production-scale reactors of the corresponding industrial processes (batch or semi-batch reactors). We shall not discuss thermal analysis devices such as DSC or other micro-calorimetric devices which differ significantly from the production-scale reactor. 

The only way to avoid this is by strict analysis of the supply chain from the customer order to final product delivery. Definition of the optimized (theoretical) process and sequential work towards a high service level approach allow the identification of gaps, and of opportunities which might not always be the cheapest (ship versus train versus plane) but could be the most effective way to reduce capital costs and shorten planning scope - an important aspect, especially in volatile customer markets with long production processes on the (chemical) supplier side. As in the case of CIP, this needs clear parameters, KPIs, commitment from all players, and regular tracking. The most important parameters are the lead time for all products, optimal lot sizes, replenishment points, and safety inventories. 

Electronic records requiring particular regulatory control should be identified based on critical process control points and associated critical parameters that directly impact product quality or product safety. A defined process should be used to conduct this analysis, and it should be one that builds on or is complementary to any assessment conducted as part of product registration. Consistency is key. There may be additional records identified by predicate rules but care must be taken not to extend beyond these records. A risk assessment should be conducted to determine appropriate electroific record management controls such as audit trail and archiving. Electronic records will need to be archived for retention periods specified in predicate rules. Other data related to process performance rather than product quality or product safety requires only basic data maintenance and may be retained for much shorter periods before being purged. 

Probably the most important characteristic of military and commercial explosives and solid rocket propellants is performance as related to end use and safety. Performance can be described by a variety of conventional properties such as thermal stability, shock sensitivity, friction sensitivity, explosive power, burning, or detonation rate, and so on. Thermal analysis methods, according to Maycock (51), show great promise for providing information on both these conventional properties and other parameters of explosive and propellant systems. The thermal properties have been determined mainly by TG and DTA techniques and isothermal or adiabatic constant-volume decomposition. Physical processes in pseudostable ma-... 

---