CHAPTER 1 INTRODUCTION
1.4. Risk and Safety Analysis Models
Table 1.2: Type of Product s Involved Contribute to Accident
Typologies
Products involved (some incidents involve more than one) Liquid
Fuels
PPG Gas
Cartridges
Other (Oils Wastes)
Unknown
Total No of Accidents Releases of
hazardous materials 199 12 5 21 3 237
Fires 20 3 5 6 27 60
Explosions 18 1 4 2 6 30
Others (near
accidents) 2 1 0 0 4 7
Total number of
accidents 202 13 5 21 32 270
Various hazards associated with petrol filling stations have occurred reported in various studies; such as fires and explosions due to open flames reported by [20], static electricity by [21], air pollution induced by aromatic organic compound concentrations by [22], and the traffic jams due to vehicle queues to access the petrol filling station [23]. It was found that these HCFs were not independent of each other and have a strong correlation.
Three widely used risk assessment models .i.e. as low as reasonably practicable (ALARP), risk matrix criterion and risk ranking criterion were used in this study.
Same data was analyzed but different results were obtained. It was due to the unavailability of guidance and instructions for the application of risk assessment models. The brief description of three risk assessment models is described below;
1.4.1. As Low as Reasonably Practicable (ALARP)
According to ALARP, all risks in a company must be managed at a level which is as low as reasonably practicable (ALARP) for that company. ALARP is implemented in oil and gas companies in Malaysia [25]. To each activity a particular consequence and probability number was assigned and it was based on the severity level. Table 1.3 shows the ALARP risk assessment matrix. The consequence levels have a rating from 0 to 5. The rating can affect people, assets, the environment and the reputation of an operating company.
Table 1.3: ALARP Risk Assessment Matrix
1.4.2. Risk Matrix Criterion
The risk matrix evaluation method is widely used in upstream oil and gas sectors in Pakistan to determine risks [26]. Risk associated with any activity depends upon 2 parameters, i.e., severity and likelihood. Risk is the multiplicative product of severity times likelihood.
Table 1.4 shows the risk matrix criterion to calculate the risk score associated with hazardous activities. During risk analysis, a severity and likelihood value is assigned to the hazardous event.
Table 1.4: Risk Matrix Criterion to Calculate Risk Associated with Hazardous Activities
The risk value can be calculated by using equation 1.1.
Risk Score = Likelihood (L) X Severity (S) (1.1)
A risk score value is calculated and put up respectively in Table 1.5. Based upon the risk score value, the hazard is categorized into one among the four main groups. The action required depends upon the category of hazard.
Table 1.5: Risk Evaluation Scale Evaluation Scale
Score Category Action Required
80 – 100 Critical
Isolate the hazard immediately. Take Corrective measures on high priority and eliminate the hazard as soon as possible.
50 – 79 Major
Isolate the hazard as soon as practicable.
Engineering control and administrative controls need to be taken. Regularly monitor the
cause(s) until rectification.
30 – 49 Moderate Must fix the cause(s) when time and resources permit. Administrative control is to be taken.
29 Minor
Need to monitor and consider. Administrative control is to be taken & use appropriate PPEs.
1.4.3. Risk Ranking Criterion
The risk ranking criterion is normally used to rank the hazards [27]. According to the risk ranking criterion, there are many processes in progress at any work place. It is not possible to tackle the entire hazard process effectively because it may be time consuming and this may cause delay to the work. Thus, a ranking system based on priority for the list of hazards to be controlled is performed to arrest the problem. All components should be assessed and the probability of the risk of hazard to occur is formulated. Table 1.6, Table 1.7 and Table 1.8 describe further steps to determine the risk score by using the risk ranking criterion.
Table 1.6: Probability of Hazard
Rating Likelihood Frequency Description
1 Highly unlikely About 1 in 1000
activity times Unlikely to happen 2 Unlikely About 1 in 100
activity times
Probably will happen but rarely
3 Likely About 1 in 10
activity times
Could happen occasionally
4 Very likely Frequent Could happen
frequently
Table 1.7: Consequences from the Hazard
Rating Severity Description
5 Not harmful (Negligible)
Hazard will not result in serious injury or illness, remote possibility of damage beyond minor first aid case.
10 Slightly harmful (Marginal)
Hazard can cause illness, injury or equipment damage but result would not be expected to be serious.
15 Harmful (Critical) Hazard can result in serious illness, severe injury, property and equipment damage.
20 Extremely harmful (Catastrophic)
Imminent danger exists, hazard capable of causing death and illness on a wide scale.
The ranking of risk can be calculated using the equation 1.2,
Risk Ranking = Probability of hazard x Consequences (1.2) Table 1.8: Priority of Action from the Risk of Ranking Risk
Ranking Action
Timescale and Urgency Low
(5,10)
Relevant action and control measures are required and records need to be kept.
Consideration need to be given for an effective solution or improvement. Monitoring is required to ensure that controls are maintained.
Within 1 week
Medium (15,20,30)
Efforts should be made to minimize the risk.
Control measures should be implemented.
Where moderate risk is associated with extremely harmful consequences, further assessment may be necessary to establish more precisely the likelihood of harm as a basic for determining the need for improved control measures.
Within 1 day
High (40,45,60,80)
Work should not commence until the control measures have been taken to minimize risk. For work in progress, take action within the same day. Work should be stopped immediately until proposed control measures has been taken satisfactorily to eliminate or minimize risk.
Immediately
The gaps were identified during data analysis in the three risk analysis approaches. A statistical approach was used and a new risk and safety analysis model was developed. The study proposes a detailed methodology for the development of a new risk and safety analysis model during the operation and maintenance of petrol filling stations.
Risk analysis models are work system design methods and are helpful to address the associated risks in a project. During the study it was felt that many resources are available within an organization to minimize accidents/injuries but due to under utilization of the resources accidents/incidents occurs. After calculating the risks, the application of available resources can be done more appropriately. In case of unavailability, requirements can be highlighted and applied strategically to get better results. The application of an inappropriate risk analysis model to calculate risk will not give suitable results because of the difference in the base data used to establish these criteria. Therefore, there is a need for a new risk and safety analysis model that can be applied to determine risks on PFS related activities. An intrinsically safe working environment is equally needed at petrol filling station.
During the study no guidelines were found with reference to the use of a particular risk analysis model for specific industrial use. It was also noticed that companies were using risk analysis methods without any consultation with the experts. It may be the root cause of occurrences of non-compliances that can lead to any catastrophic event. This can be considered as the main cause for occurrences of fatalities, accident and incidents in industries. Therefore, there is a need for the development of industry specific risk analysis models.