Inputs to the Design Process

The standard requires that organizational interfaces between different groups which input to the design process be identified and the necessary information documented. 

Operator inputs to the design process as well as extensive simulation and testing will assist in designing usable computer displays. Remember that the overall goal is to reduce the mental workload of the human in updating their process models and to reduce human error in interpreting feedback. 

Site related information represents a very important input to the design process and may be one of the sources of uncertainty in the final safety evaluation. The measures employed to account for such uncertainty levels should be considered in the SAR. 

As noted in Step 13 of the inherent safety review at the design development stage, the team reviews the process to develop a list of potential ergonomics/human factors issues. This list provides input to the design team so that these issues can be addressed as the design progresses. 

The target level assessment process for paper machine halls is the result of long historical development. The performances of installed paper machine hall ventilation systems are measured very often and the results are compared with input data used as the basis for design. As a result of these comparisons corrections are made to the design process as necessary. 

Since the mental model elicited by IMAS explicitly identifies the information needed to identify the causes of disturbances (and to distinguish among alternative causes), it can be used to specify the critical variables that need to be readily available to the process controller at the interface. This information can be used as an input to the design and upgrading of interfaces, particularly when new technology is being installed. 

However, current CFD cannot provide good predictions of HRR evolution (i.e., hre growth) in real complex enclosures/scenarios. Fire modeling is not yet able to predict the HRR, and research efforts need to be tailored toward this issue. However, hre environments for hre safety design can still be calculated using CFD, if the HRR is an input data to the design process. This is because, current CFD tools provide good predictions of the effects of a hre (e.g., temperature held, smoke movements, etc.) once the HRR is provided. 

Figure 12.1 shows the interactions between development and operations. At the end of the development process, the safety constraints, the results of the hazard analyses, as well as documentation of the safety-related design features and design rationale, should be passed on to those responsible for the maintenance and evolution of the system. This information forms the baseline for safe operations. For example, the identification of safety-critical items in the hazard analysis should be used as input to the maintenance process for prioritization of effort. 

Setting up a safety information system for a single project or product may be easier. The effort starts in the development process and then is passed on for use in operations. The information accumulated during the safety-driven design process provides the baseline for operations, as described in chapter 12. For example, the identification of critical items in the hazard analysis can be used as input to the maintenance process for prioritization. Another example is the use of the assumptions underlying the hazard analysis to guide the audit and performance assessment process. But first the information needs to be recorded and easily located and used by operations personnel. 

New technologies may have a broad effect on the p onnance and capabilities of new products. Thus, as an input to the requirements process, new technologies should be assessed for thdr value to improving the product s design or capabiUty. 

Primary documents are those documents that are integral to the design process and which constitute the input and output documents for each of the phases. A fault in these documents can lead directly to a fault in the system itself. Primary documentation typically inclndes documentation of the design basis for the purpose of the plant safety analysis, documentation of the safety systems requirements, logic diagrams and as-bnilt drawings. 

Given the complexity of the piston assembly system and particularly the important role of lubricant chemistry in controlling wear and lubricant rheology, empirical data from laboratory and engine tests will remain a key input to the design optimisation process in the medium term. 

Good design ideas for new plants are also good for existing plants, but there are three basic differences. (/) Because a plant already exists, the capital—operating cost curve differs. Usually, this makes it more difficult to reduce utiHty costs to as low a level as in a new plant. (2) The real economic justification for change is more likely to be obscured by the plant accounting system and other nontechnical inputs. (2) The real process needs are... 

A future goal for the integration of graphics and process design simulators is to be able to use an interactive graphics program to prepare the input to the process simulator. This capabiHty would allow tme on-line process modification, flow-sheet optimization, and process optimization, and is likely to be one of the key developments in this field in the 1990s (99). 

Flow-sheet models are used at all stages in the life cycle of a process plant during process development, for process design and retrofits, and for plant operations. Input to the model consists of information normally contained in the process flow sheet. Output from the model is a complete representation of the performance of the plant, including the composition, flow, and properties of all intermediate and product streams and the performance of the process units. 

Introduction An accurate quantitative analysis of the discharge of pollutants from a process must be determined prior to the design and/or selection of control equipment. If the unit is properly engineered by utilizing the emission data as input to the control device and the code requirements as maximum-effluent limitations, most pollutants can be successfully controlled. 

As design documents are often produced at various stages in the design process they should be reviewed against the input requirements to verify that no requirements have been overlooked and that the requirements have been satisfied. 

---