# HAZOP Analysis in Terms of Safety Operations Processes for Oil Production Units: A Case Study
## 3 Case Study: HAZOP Analysis of a Crude Oil Production Unit  
The analysis was conducted by the HAZOP team leader and supported by a secretary. Engineers from the operating company (production engineer, maintenance engineer, safety, health and environment engineer, and a facility engineer) also participated in the study. The complete examination of the facilities took five days to be carried out, with an average duration of 8 h of analysis per day.  
For analysis, the entire installation was divided into 13 areas or key points designated by nodes, which corresponds to 100%. Only the results of the first six nodes, approximately 50% of the installations, were presented and analysed in this paper. Table 1 describes the nodes briefly. The steps that comprise a HAZOP analysis are described below:  
1. Selection of nodes: the nodes were defined according to the functioning and operation of the equipment and accessories in their neighborhood. The six nodes examined during HAZOP sessions are briefly described in Table 2.
2. Choice of guide words and process limits: words that describe the unit's process parameters (pressure, temperature, flow, level and corrosion), associated with words that indicated deviations in the normal operation of the unit, called guide words (high, low, none, inverse/reverse, and other). The combinations of these words used throughout the analysis/study that assigned indicators of equipment functioning (nodes), showing whether they would be operating inside/outside the standard (deviations) of operation, allowing the identification of hazards--for example, high pressure, low temperature, or none flow.
3. Identification of the source of deviations or causes of hazards: with the system divided into smaller sections and each one with the parameters and keywords adequately identified, the risk analysis was carried out by testing the hypothesis of improper functioning of the equipment. Based on the probable trends of deviations observed, it was sought to predict the result, that is, the consequences. If the variation in the parameter represented a hazard, that problem was documented, and its impact was later estimated.
4. Risk frequency analysis: the frequency analysis was made based on estimates of the probability of occurrence of scenarios that were predicted to be dangerous. The frequencies were synthesised using models of frequency estimates. Synthesising the frequencies involves determining combinations of failures and circumstances that may cause the scenarios of interest, using the consulting firm's procedure manual (adapted from BS IEC 61882: 2001) [20].
5. Determination of consequences: the analysis of the consequences was based on the statistically estimated results of a target population regarding the risk of interest and the effects on safety/health related to this level of exposure (Criteria described in the CCPS manual, 2011). Consequence estimates were made according to a risk matrix (Table 2), measuring the level of impact of the consequences in association with safety, environment, and economy [23].
6. Setting barriers: to prevent the consequences of the identified risks from being implemented, measures were taken to mitigate or eliminate these risks; these measures were established to prevent the progress of a situation that could become potentially disastrous; for this reason, the measures are called barriers. These barriers were recorded on the HAZOP sheet.
* Recommendations: at the end of the assessment, recommendations were made on the potential hazards identified in the previous steps to reduce the level of risks analysed and discussed by the HAZOP team.