Refer to Chapter 7 for detailed information regarding creating and using cost databases.
The energy cost for the pumps was specified in the Cost Settings as a fixed cost rate. Now, the material and installation cost for the pumps, pipes, and fittings must be included. This will be done by creating two new cost databases. The first database will be for the pipe and fitting costs, and it will be associated with the engineering database that contains the pipe material data. The second cost database will be for the pump costs, and it will be associated with the engineering database that contains the pump component information.
Create a new cost database for the pipe costs
Create a new cost database for the pipe costs by opening the Cost Database window from the Database menu. Create a new cost databaseby clicking on the New button. When you click on the New button, you are prompted to choose the engineering database with which the cost database will be associated
The piping material data used in the model comes from the default AFT internal database, so the pipe cost database will be connected to this database, as well. Select AFT DEFAULT INTERNAL DATABASE from the database list shown in the Select Database window, then click the Select button.
Important: Make this choice carefully, because once you have made the association you cannot change it.
Once the database is created, you must enter a meaningful description and select the cost units. Enter the following data on the General tab:
1. Cost Type = Monetary 2. Monetary Unit = U.S. Dollars
3. Description = Plant Cooling System – Sch20 Steel Piping Costs 4. Notes = This database is for the Plant Cooling CST Example File Save the cost database to a file by clicking the Save button. When prompted, choose to add the new database to the list of available and connected databases. The information on the General tab should appear as shown in Figure 9.3
Note: The database file pathnames may be different than those shown in Figure 9.3.
For this example, you will enter Pipe Material costs, Junction costs for the pumps, and Fittings and Losses costs for the pipes.
Enter the pipe material costs
After the pipe cost database has been created, select the Pipe Materials tab in the Cost Database window. This is where you will enter the material and installation costs for the piping.
The selected database file information is displayed
The cost type and monetary units are specified
A description of the cost database must be given
Descriptive notes can be added to provide additional information about the database
Figure 9.3 The Cost Database window is used to enter cost database data.
The Pipe Materials tab shows all the pipes in the engineering database (AFT DEFAULT INTERNAL DATABASE). Costs can be entered at several levels. You can enter costs at the material level, the nominal size level, and finally at the type (i.e., schedule) level. Costs entered at the material level apply to all nominal sizes and types in that material type.
Costs entered at the nominal size level apply to all schedules within that nominal size. Costs entered at the type (schedule) level apply only to that type. For this example, all of the pipe material costs will be entered at the type (schedule) level.
To enter a new cost, navigate to the material, nominal size and type combination for which you want to enter a cost. Click the New Cost button to create a new cost item in the table below. The new cost item will appear as a new column.
Each pipe size in this example has two non-recurring costs associated with it. The costs to be entered are the material and installation costs.
Figure 9.4 shows the costs entered for 8-inch Schedule 20 Steel. Enter the non-recurring pipe costs for the pipe in this example, as shown below.
All pipes are Schedule 20 Steel – Size
(inches)
Material Cost (dollars/foot)
Installation Cost (dollars/foot) 8 10.50 24.00
14 22.50 51.50
18 27.40 70.00
20 35.40 85.50
24 40.00 96.50
28 58.00 110.00 30 60.00 129.00
Figure 9.4 Non-recurring pipe costs, such as material and installation costs, are entered on the Pipe Materials tab.
Create cost scale tables
The pipes in the model have 90 deg. elbows specified as fittings and losses. The cost of these 90 deg. elbow items can be included in the cost calculation. The costs for these items will be accounted for in scale tables. Scale tables can be used to vary a cost with a parameter such as diameter (i.e., size). Once created, this scale table can be applied to the fitting/loss items.
The first table you will create is the scale table for the 90-deg. elbow installation costs. Select the Tables tab, and click the New Table button.
Enter the following data for the scale table on the New Scale Table window:
1. Name = 90 Elbows Installation (Sch20, 8-34) 2. Table Type = Diameter
3. Table Format = Cost
The window should appear as shown in Figure 9.5. After entering the data, click the OK button.
After the table has been created, enter the cost data for the table. Do this by selecting the table name in the Table list, then entering the cost values in the table provided. Enter the following installation cost data into the scale table:
You do not need to enter data in the scale tables for every diameter in the model. If a diameter falls between two data points in the table, the CST module will use the points on either side to linearly interpolate for a
value. If the cost function is non-linear, you may need to add additional data points to achieve a more accurate cost value.
Create another scale table for the material costs using the following data:
1. Name = 90 Elbows Material (Sch20, 8-34)
After the scale tables have been created, and the cost data entered, the Tables tab should appear as shown in Figure 9.5.
Add the costs for pipe fittings
With the cost scale tables for the fittings defined, the costs for the pipe fittings can be added. Select the Pipe Fittings and Losses tab. A list of all of the available fittings and losses is displayed in the Pipe Fittings and Losses list.
The fittings in the model are 90-deg. smooth flanged elbows, with an r/D ratio of 1. Navigate through the list until you find the proper selection for these fittings.
Figure 9.5 The Tables tab on the Cost Database window is used to create cost scale tables.
Add the material cost by clicking the New Cost button, and entering the following data:
1. Description = Elbow Material Costs 2. Cost Type = Material (NR)
3. Material = Steel
4. Material Size = All Sizes 5. Material Type = All Types 6. Use Size Table = Table of Costs 7. Multiplier = 1
8. Size Scaling Table = 90 Elbows Material (Sch20, 8-34) Now add the installation cost by clicking the New Cost button, and entering the following data:
1. Description = Elbow Installation Costs 2. Cost Type = Installation (NR)
3. Material = Steel
4. Material Size = All Sizes 5. Material Type = All Types 6. Use Size Table = Table of Costs 7. Multiplier = 1
8. Size Scaling Table = 90 Elbows Installation (Sch20, 8-34) The actual cost values used for the fittings are the values that were entered in the scale tables on the Tables tab. The scale table to use for each cost is specified when the cost is defined. After the cost data is entered, the Pipe Fittings & Losses tab should appear as shown in Figure 9.6.
Figure 9.6 The Pipe Fittings & Losses tab on the Cost Database window is used to specify costs for pipe fitting/loss items.
Create a new cost database for the pumps
To enter cost for a pump, or any other junction type, the junction must first be added to an engineering database. Cost data is then entered in a cost database associated with that engineering database. The pumps used in this example have been added to an engineering database. Create a new cost database associated with the Plant Cooling engineering database with the following general information:
1. Cost Type = Monetary 2. Monetary Unit = U.S. Dollars
3. Description = Plant Cooling Circ Pump Costs
Save the cost database to a file by clicking the Save button. When prompted, choose to add the new database to the list of available and connected databases
Enter the pump costs
After the pump cost database has been created, select the Junctions tab in the Cost Database window. This is where you will enter the material and installation costs for the pumps.
All of the junctions that are available in the selected engineering database will be listed. Select the Cooling Tower Circ Pump from the list of pumps.
Add the material cost by clicking the New Cost button, and entering the following data:
Material Cost = $28,500
Add the installation cost by clicking the New Cost button, and entering the following data:
Installation Cost = $12,500
Figure 9.7 shows the pump costs entered in the cost database.
Figure 9.7 The Junctions tab on the Cost Database window is used to specify costs for junctions.
Connecting the cost databases
The cost databases should have been added to the list of available database, and been connected to the example model. If they were not, you can use the Database Manager to connect the cost databases now (see Figure 9.8). Refer to Chapter 7 for information on how to connect databases using the Database Manager.
Figure 9.8 Database Manager with connected engineering and cost databases.