Preliminary design phase

The preliminary design phase is also where sufficient design work is done to assure operability of the project without additional scope. The first step is to evaluate what work must be done to assure that the required scope is comprehensive for the project what work must be done, to what detail, to achieve the required accuracy of the estimate (Fig. 3). If a conceptual estimate has been made, a quick study of it shows which are its largest accoimts and then focus can be on the improvement of their accuracy. A second review that is painfully forgotten is the evaluation of the project for overall completeness of the scope. Questions to ask at this point are  

Warehouse Roadway Site drainage Security Phone system Fire protection  

IS THE SOLUTION FEASIBLE IS THE SOLUTION COMPLETE IS THE ESTIMATE SUITABLE  

Here is but a partial list of the questions to be asked so that unestimated scope does not enlarge the project beyond its estimated accuracy and interfere with its profitability. At some point in preliminary design, a project logic meeting is in order where the sole focus is uncovering potential flaws in the project s logic. A blend of those most knowledgeable about the project and seasoned evaluators less immediately involved with the project can best perform this effort. 

If the project has sizable architectural considerations, it is important they be properly estimated. Those dollars per square foot numbers that are so useful early in the project need to be firmed up. For the biotech and dosage pharmaceutical projects of today, it is as important that the building costs be as accurate as the equipment costs. Sometimes an account-by-account evaluation for estimating accuracy is in order to see if sufficient work has been done to assure the validity of the overall estimates accuracy. 

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For example a process flow scheme for crude oil stabilisation might contain details of equipment, lines, valves, controls and mass and heat balance information where appropriate. This would be the typical level of detail used in the project definition and preliminary design phase described in Section 12.0. 

Most of the principles of inherent safety are useful in the preliminary design phase even most process details are still missing. This is represented in Table 4 which shows in which project phase each inherent safety feature should be considered. In fact the opportunities for installing inherent safety features decrease as the design progresses (Kletz, 1991). It can be seen from Table 4 that most features can be considered in the conceptual and flow sheet stage. 

The second approach is simulation. Production scheduling and performance measures of the ship (such as fuel consumption) are vital for bid creation whereas during the concept design phase the focus is set on production scheduling, ship performance is the key topic in the preliminary design phase. The basic design focuses on defining the parameters for the product to meet the requirements. 

The preliminary design phase consists of the development of a high-level design of the code based on the requirements. 

System design review (SDR) the hardware SDR immediately follows the preliminary design phase and will encompass a top-level review of the system hardware characteristics such that preliminary design may proceed with confidence. Key hardware characteristics will be reviewed at this stage to ensure that there are no major mismatches between the system requirements and what the hardware is capable of supporting. 

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