Frequent Crisis and Modern Trends Associated with HAZOP Study in Plants and Industrial Units

Hazard and operability (HAZOP) analysis has a well-deserved reputation for systematic and thorough evaluation of process hazards in industrial units. The method is now widely known and is in prevalent use in the chemical processing industries; so much so that in many industries performing a HAZOP has become a legal requirement for new or modified industrial units. A number of guides exist for conducting HAZOPs, the most recent being the IChemE guidelines on finest practice – second edition, published in the year 2008. In exercise however, following best practice is not that easy and many compromises have to be made in order to finish the task an added hurdle occurs when the HAZOP is led by a self-governing leader from an external company or third party as is increasingly the case. In this circumstance the person in charge also has to satisfy the customer or customer’s requirements which do not always match to the best custom. In addition there is a drift to lessen HAZOP study scope to safety health and environmental concerns only and to exclude operability and consistency issues. This has resulted from a observance mindset, possibly in an attempt to lessen liabilities. HAZOP is increasingly being seen as a conformity tool rather than as a tactic to ensure a secure, trustworthy and well designed plant. With the current financial environment we can expect these hitches to increase as project costs come under enhanced pressure and the extent of many projects is reduced. This paper discusses some of the more frequent crisis that occur during HAZOPs and some of the possible solutions in industrial units.

Risk Assessment of Releasing Flammable Material from Liquefied Petroleum Gas Tanks by Bowtie Method and Vulnerability Zoning by PHAST Software

Introduction: The release of storage tanks' contents can lead to consequences such as BLEVE, explosions, fires, etc. Therefore, identifying the causes of content release, determining the scenarios, consequences, and possibility of incidents are required to prevent possible accidents. Moreover, the vulnerability and safety ranges should be determined to minimize the losses. Methods: In this research, the Bowtie method was used to evaluate the risk caused by the pressurized reservoirs. After identifying the risks of process hazards and determining the main, middle, and base events, the fault tree was mapped. Then, the events probability was calculated. In the next step, the event tree was designed to determine different scenarios of events and identify the consequences of each incident. Later, the probability of consequences was calculated. The Bowtie diagram was designed in the next step. Finally, the vulnerability zone was determined for each of the consequences using the PHAST software. Results: Considering the Bowtie's analysis, a total of 27 events including 21 base events, six mid events were determined. Furthermore, 15 minimal counts along with their event probabilities and importance were identified. In this regard, nine outcomes and scenarios were determined along with their probabilities. The widest human vulnerability zone was related to cloud and steam explosions. Conclusion: Leakage from the reservoir and connections, overflow, and PRVs are among the important defects of liquefied petroleum gas reservoirs. Considering the high probability of consequences and in order to prevent from the severity and damages of accidents, systems such as cooling system and fire stop system are required in the unit.

Correlating Quantitative Risk Assessment and Exergy Analysis for Accounting Inefficiency in Process Hazards: A Case Study

The core of the work is the investigation of the possible correlation between the thermodynamics and the hazards of a process. The objective is understanding the role of inefficiency in hazards consequences. To investigate such correlation, a case study from oil and gas sector is developed, where exergy analysis is used to study the thermodynamics of the process and a simplified quantitative risk assessment (QRA) is performed to evaluate the consequences of identified hazards. The thermo-economic approach is then used to correlate the two analyses. Through the analysis, the authors want to identify those components where hazardous consequences may be affected by inefficiency, aiming to reduce the risk of fatalities in processes by operating on the process itself or suggesting possible alternative strategies. The purpose of the paper is also to propose for further investigation on the correlation between inefficiency and process hazards.