Hazard analysis structures

Process Hazard Analysis (PHA) A structured procedure whereby hazards associated with a process are identified and evaluated. 

The next sections of the checklist are based on the structure of the Technical Guidance for Hazards Analysis, and include ... 

Figure 3.1. Process Hazard Analysis Task Structure...

Lattimer, B.Y., Wright, M., and Cutonilli, J. 2000. Composite Fire Hazard Analysis Tool for Topside Structures (CTHAT) - Version 3." NSWCCD-TR-65-2000/32. U.S. Navy Surface Warfare Center Carderock Division, Washington, DC. 

Morphological Approach— A structured analysis of an incident directed by insights from historic case studies but not as rigorous as a formal hazard analysis. 

Hazard analysis of critical control points (HACCP) has been widely used in the food industry and is becoming more commonly used in the pharmaceutical industry (Jahnke, 1997). HACCP is a tool for evaluating steps in a manufacturing process. It provides a structured thought process for GMP. The seven steps involved are ... 

Hazard analysis in process development is more a philosophy than a precise program. The complex and changing nature of process development requires the scientist to be constantly on guard for the unexpected and the unknown. Such programs must be flexible as well as structured most of all, they must become an established, well-integrated part of all development activities. 

For distillation columns Add sufficient trays to account for disturbances and anticipated expansion of production. The expected turndown ratios affect the choice of internals in a distillation column with a large turndown ratio, suggesting the use of bubble caps a low turndown ratio may point to structured packings. At the same time, safety and hazard analysis indicates that we want a minimum of liquid holdup in the system. 

Hierarchical Approach is a simple but powerful methodology for the synthesis of process flowsheets. It consists of a top-down analysis organised as a clearly defined sequence of tasks grouped in levels. Each level solves a fundamental problem as, number of plants, input/output structure, reactor design and recycle structure, separation system, energy integration, environmental analysis, safety and hazard analysis, and plantwide control. At each level, systematic methods can be applied for the synthesis of subsystems, as chemical reaction, separations, or heat exchangers network. 

DOE 0 420.1 Facility Safety Requires fire hazard analysis and natural phenomena analysis for all facilities. For Hazard Category 2 or 3 nuclear facilities only, requires a criticality safety evaluation. Criticality Safety Analysis Fire Hazard Analysis Effects of natural phenomena hazards on facility systems, structures, or components (SSCs) included as part of safety analysis documented in the Safety Analysis Report (SAR), Basis for Interim Operation (BIO), or Auditable Safety Analysis (ASA). 

STAMP provides a direction to take in creating these new hazard analysis and prevention techniques. Because in a system accident model everything starts from constraints, the new approach focuses on identifying the constraints required to maintain safety identifying the flaws in the control structure that can lead to an accident (inadequate enforcement of the safety constraints) and then designing a control structure, physical system and operating conditions that enforces the constraints. 

Technical Authority (ITA) recommended in the report of the Columbia Accident Investigation Board. The risk analysis itself is described in the chapter on the new hazard analysis technique called STPA (chapter 8). But the first step in the safety or risk analysis is the same as for technical systems to identify the system hazards to be avoided, to generate a set of requirements for the new management structure, and to design the control structure. 

The control structure was later changed to have ITA under the control of the NASA center directors rather than the NASA chief engineer therefore, this control structure does not reflect the actual implementation of ITA at NASA, but it was the design at the time of the hazard analysis described in chapter 8. 

As designed, this safety control structure looks strong and potentially effective. Unfortunately, it has not always worked the way it was supposed to work and the individual components have not always satisfied their responsibilities. Chapter 8 describes the use of the new hazard analysis technique, STPA, as well as other basic STAMP concepts in analyzing the potential risks in this structure. 

Structured process for hazard analysis. The information from the first step (identifying the unsafe control actions) is required to perform the second step (identifying the causes of the unsafe control actions). 

Figure 8.1 shows the control structure for this simple system. In this figure, the components of the system are shown along with the control instructions each component can provide and some potential feedback and other information or control sources for each component. Control operations by the automated controller include turning the power off and turning it on. The human operator can open and close the door. Feedback to the automated controller includes an indication of whether the door is open or not. Other feedback may be required or useful as determined during the STPA (hazard analysis) process. 

The safeguards may be in the design of the system itself or in the design of the operational safety control structure. Because operational safety depends on the accuracy of the assumptions and models underlying the design and hazard analysis processes, the operational system should be monitored to ensure that ... 

To accomplish these goals, a feedback control loop is needed to regularly track and assess the effectiveness of the development safety control structure and its controls. Were hazards overlooked or incorrectly assessed as unlikely or not serious Were some potential failures or design errors not included in the hazard analysis Were identified hazards inappropriately accepted rather than being fixed Were the designed controls ineffective If so, why ... 

Before any planned changes are made, including organizational and safety control structure changes, their impact on safety must be evaluated. Whether this process is expensive depends on how the original hazard analysis was performed and particularly how it was documented. Part of the rationale behind the design of intent specifications was to make it possible to retrieve the information needed. 

The What-lf method (spelled here in the same way as it is printed in the OSHA PSM regulation, i.e., hyphenated but with the question mark omitted) is the least structured of the hazards analysis techniques. This method also takes the least amount of time. 

PhiUey, J., 2011. Structured What-if Approach to Process Hazards Analysis. 24th Annual TCC/ACIT EHS Seminar. 

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