Layered safety audits

Based on these results, Du Pont refined its approach to safety into its present Safety Training Observation Program (STOP). Du Pont promotes STOP extensively both within and outside the company. STOP involves a process of layered safety audits in which each layer of management conducts a regular safety audit, typically every week. A manager enters an area and finds its superintendent then they conduct a safety audit of that area. On a different week, the superintendent chooses an area supervisor and they conduct a safety audit. Further, all management personnel conduct a formal audit each week in one of the work areas for which they are responsible while also conducting informal observations of both safety practices and safe work conditions at all times. 

Safety audit report written records, together with the audited entity feedbacks are responsible for safety audit for review, modification to form an audit report. Then the reports should be submitted to the audited entity and signed by management layer. 

The safety audit of the landfill B detected some failures due to the fact that the procedures and rules given by the Operating rules are not followed. As the most serious failure is considered the fact, that the majority of wells to maintain underground water level in the old landfill was filled further failures are insufficient over covering of the stored waste with inert material and a delay in increasing of the sealing layer in the wall of the landfiU. 

A similar process involving layers of control is found in the system operation control structure. In addition, there will be (or at least should be) interactions between the two structures. For example, the safety design constraints used during development should form the basis for operating procedures and for performance and process auditing. 

A Center for Chemical Process Safety (CCPS) publication gives the following definition An IPL is a device, system or action which is capable of preventing a scenario from proceeding to its undesired consequence independent of the initiating event or the action of any other layer of protection associated with the scenario. The effectiveness and independence of an IPL must be auditable [12]. Discussions on layer of protection analysis (LOPA) were covered in Chapter V, so they are not repeated here. However, a few characteristic features of protection layers are presented. Similar to fault tolerance and security, this is also important so that the control system is always safe. As per lEC 61511 standard the core idea for integrated safety and security is defense-in-depth with independent layers of protection to reduce process risk. The strategy behind this is that the BPCS, critical... 

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