Preliminary hazard analysis system operation

Common hazard analysis tasks include the preparation of a preliminary hazard analysis, systems and subsystem hazard analyses, and an operating hazard analysis. These tasks also aid in the hazard control and hazard reduction effort. 

The MORT tools and techniques can be helpful in preparing a safety analysis report (SAR), the upstream safety product most frequently required for new DOE programs, but the more common system safety products (system safety program plan, preliminary hazard analysis, system/subsystem hazard analysis, operating hazard analysis) are not a dominant part of the MORT program and are seldom even referenced in System Safety Development Center (SSDC) documents. 

Laundry lists of analyses frequently mix types of analyses (preliminary hazard analysis, system hazard analysis, and operating hazard analysis) with the methods or techniques for performing analyses (fault tree analysis, energy trace and barrier analysis, failure modes and effects analysis, common cause analysis, change analysis, and so on). Whether fault hazard analysis is a type or a method depends upon the reference in use. For all practical purposes, fault hazard analysis and system (or subsystem) hazard analysis seem to be the same thing, which is apparently called gross hazard analysis occasionally. 

The Demo 11 tests showed that the safe operation of this high-temperature hydrogen process could be achieved in the relatively short time allowed for construction of the equipment, systemization, and training of Army operators. However, a preliminary hazards analysis must seriously evaluate the use of hydrogen in a closed area. 

Again the process involves a preliminary hazard analysis to be done very early in the concept stage, followed by subsystem hazard analysis as subsystems are developed, systems hazard analysis that looks at interfaces between subsystems, and, finally, the operating hazard analysis, which tends to add the human element and evaluate procedures. 

The HazOp study differs from the FMEA and ETBA in that some suggest that the best time to conduct a HazOp is when the design is fairly firm (Goldwaite 1987). Conventional system safety wisdom dictates that the system safety effort be as far upstream as practical, with a facility preliminary hazard analysis developed as part of the initial design effort and completed by the 35% stage. Also, a HazOp study tends to include human factors and operator errors whereas a traditional FMEA or ETBA normally examines hardware failures only. 

Preliminary drawings or sketches may be adequate to prepare a preliminary hazard list. More detailed drawings are required for a preliminary hazard analysis, and even more detail is required for subsystem and system hazard analyses. Analytical trees, copies of maintenance and operating procedures (if available), and site maps may also be helpful. 

The purpose of the project evaluation tree is to provide a relatively simple, straightforward, and efficient method of performing an in-depth evaluation or analysis of a project or operation. It is best suited for performing operating hazard analysis and accident analysis. It can also be a valuable review and inspection tool. If adequate information is available, PET analysis may be helpful in performing preliminary hazard analysis, subsystem hazard analysis, and system hazard analysis. 

The SSHA evaluates hazardous conditions, on the subsystem level, which may affect the safe operation of the entire system. In the performance of the SSHA, it is prudent to examine previous analyses that may have been performed such as the preliminary hazard analysis (PHA) and the failure mode and effect analysis (FMEA). Ideally, the SSHA is conducted during the design phase and/or the production phase, as shown in Chapter 3, Figure 3.4. However, as discussed in the example above, an SSHA can also be done during the operation phase, as required, to assist in the identification of hazardous conditions and the analysis of specific subsystems and/or components. In the event of an actual accident or incident investigation, the completed SSHA can be used to assist in the development of a fault tree analysis by providing data on possible contributing fault factors located at the subsystem or component level. 

The ETBA is an analytical technique that can be of great assistance in preparation of the preliminary hazard list (PHL). It can also be quite useful in the development of a preliminary hazard analysis (PHA), subsystem hazard analysis (SSHA), or the more general system hazard analysis (SHA). The ETBA can also be used, depending on the specific system under consideration, in the development of the operating and support hazard analysis (O SHA), and, of course, during the MORT process from which the ETBA evolved. 

The second and more common hardware FMEA examines actual system assemblies, subassemblies, individual components, and other related system hardware. This analysis should also be performed at the earliest possible phase in the product or system life cycle. Just as subsystems can fail with potentially disastrous effects, so can the individual hardware and components that make up those subsystems. As with the functional FMEA, the hardware FMEA evaluates the reliability of the system design. It attempts to identify single-point failures, as well as all other potential failures, within a system that could possibly result in failure of that system. Because the FMEA can accurately identify critical failure items within a system, it can also be useful in the development of the preliminary hazard analysis and the operating and support hazard analysis (Stephenson 1991). It should be noted that FMEA use in the development of the O SHA might be somewhat limited, depending on the system, because the FMEA does not typically consider the ergonomic element. Other possible disadvantages of the FMEA include its purposefiil omission of multiple-failure analysis within a system, as well as its failure to evaluate any operational interface. Also, in order to properly quantify the results, a FMEA requires consideration and evaluation of any known component failure rates and/or other similar data. These data often prove difficult to locate, obtain, and verify (Stephenson 1991). 

The Preliminary Hazard Analysis (PHA) is an analysis of the generic hazard groups present in a system, their evaluation, and recommendations for control (TAI 1989). The PHA is usually the first attempt in the system safety process to identify and categorize hazards or potential hazards associated with the operation of a proposed system, process, or procedure. In many instances, however, the PHA may be preceded with the preparation of aPreliminary Hazard List (PHL). The identification of hazards on a PHL can occur through the use of a variety of methods such as but not limited to... 

In this paper we review the application of DP in harsh climate conditions more specifically we focuses on the Arctic conditions and the conditions in the South China Sea. Moreover, the paper deals with a preliminary hazard analysis of DP systems in such operational conditions. In this paper in section 2 the DP working conditions in Arctic... 

As a first step a Preliminary Hazard Analysis (PHA) was performed to investigate the co-operative system with the intention to identify the hazards of road traffic. (Read more about the PHA method in [5].) It became clear that the main risks arise from stored kinetic energy (vehicle collisions) and we may neglect rarely emerging hazards like chemical energy from fuel transports and the like. 

In June 1966, MIL-S-38130 was revised. Revision A to the specification once again expanded the scope of the SSP by adding a system modernization and retrofit phase to the defined life-cycle phases. This revision further refined the objectives of an SSP by introducing the concept of maximum safety consistent with operational requirements. On the engineering side, MIL-S-38130A also added another safety analysis the Gross Hazard Study (now known as the Preliminary Hazard Analysis). This comprehensive qualitative hazard analysis was an attempt to focus attention on hazards and safety requirements early in... 

There are many methods available in the published literature that can be used to perform various types of risk analysis in marine systems. These include fault-tree analysis (FTA), failure modes and effects analysis (FMEA), hazards and operability analysis (HAZOP), preliminary hazard analysis (PHA), interface safety analysis (ISA), probabilistic risk analysis (PRA), event-tree analysis (ETA), safety/review audits, and "what-if" analysis [38 2]. 

---