Piping layout model

The first five methods are apphcable only after rigorous circuit analysis and when piping layouts and isometric drawings or scale models are available for quantity takeoff (e.g., pipe size, length, and specification, flanges and valve count, etc.). 

Plant model costs vary depending upon the degree of detail included. Considerable decision making information can be obtained from a set-up of block layout only, and these costs would be extremely small. For a reasonably complete scale piping detail model the costs are reported as O.I to 0.6 percent of the cost of the plant. The large plants over 20 million cost in the lower 0.1 percent range while small plant models cost in the 0.6 to 1.0... 

Paton [15] reports total model costs of 0.4 to 1.0 percent of erected plant costs for a 1 million plant. These are actual costs and do not reflect profits. Material costs are less than 10 percent of total model costs, and usually less than 5 percent. For a. 30 million plant model costs run as low as 0.1 percent. These are for models which include plant layout, piping layout, and piping details. If simpler models are used the costs should be less. 

The ease of electronic transfer of information. Piping drawings can be generated directly from the layout model. Bills of quantities materials, valves, instruments, are generated automatically. 

Figure 1-16B. Detailed layout and piping model for a refinery unit. Courtesy of Socony Mobil Oil Co. Inc.

In the detailed design stage, everything must be specified. Each phase of the preliminary design must now be done in much more detail. The flow sheets develop into piping and instrument diagrams. The duty requirements for a piece of equipment become a specification sheet. The layout drawings may be replaced by a scale model, and a construction bid or detailed cost estimate is obtained to verify the previous cost estimate. 

Some companies use it only to obtain a rough three-dimensional view of the plant. Others include on it all pipes, valves, and electrical lines. In this case, a large number of orthographic drawings and layouts will be eliminated. In some cases the dimensions for some piping may be taken directly off the model, although usually a pipe sketch is also included (see Fig. 12-3) for each pipeline. This is sometimes... 

For fluid handling plants. Based on average of actual cases. For solid handling plants - best estimate. Piping work hours breakdown P ID drafting 0.07 Layouts 0.05 Model 0.10 Orthographies 0.33 Material take-offs 0.10 Stress analysis 0.05 Isometrics 0.30 ... 

Detailed design engineering of process equipment, piping systems, control systems and offsites, plant layout, drafting, cost engineering, scale models, and civil engineering ... 

In contrast to these generic tools, the second group of domain-specific software tools addresses certain tasks during the design process in the chemical engineering domain. They can roughly be classified as data retrieval, synthesis, and analysis tools. A typical example for data retrieval tools are physical property systems [1048, 1053[. Synthesis tools include flowsheet synthesis [951, 1039], plant layout and pipe routing [955], model development ]54, 558] or even solvent selection [7.37]. The most prominent examples of analysis tools are process simulators for steady-state ]518, 556, 1046] and dynamic simulation ]288, 518, 916]. 

A portion of the MTG model is shown in Fig. 7. The use of plastic models enables engineering contractors to eliminate the preparation of the complex orthographic piping drawings. It also facilitates the review and approval of the plant layout by the owners and minimizes errors caused by interference between piping, structural steel and concrete. 

Figure 6.1 shows the layout of the system being modelled. The compressible fluid is being carried from an upstream vessel at pressure pi to a downstream vessel at pressure p. The pressure just inside the entrance to the pipe is pi, where in general P2 p - The pressure just inside the outlet of the pipe is py. For many cases, py = P4, but this does not hold for the case of choked flow, where py > p. ... 

After process and plant design studies have been made (Chaps. 3 through 9), construct a model of the plant, including piping, instrumentation, equipment, and bviild-ing layouts. Then draw detailed instrumentation, piping, and equipment layout flow sheets, (See Fig. 3-9 as a possible method.)... 

Scale Models. Recent developments in the u of scale models have shown the advantages of this method over the detailed two-dimensional method. Figure 5-4 is a view of a study mode costing less than 1,000. It was made from blocks of wood and cardboard set on in. to the foot scaled paper. This low-cost model is used chiefly to develop plot and elevation plans and cannot be used for piping and utilities layout. Figure 5-5 is a more complete model costing 5,000 to 10,000. It is... 

The pipe designer has been given process and engineering flow sheets and equipment layout drawings with or without scale models. He has chosen pipe sizes and materials according to the methods discussed in... 

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