# Data Entry - Pipes

Data entry for pipes is the same for all materials of construction. If you click on a pipe in the flowsheet the Input Editor displays the basic pipe information shown below. Figure 1: General Pipe Input. Unique Name: Allows you to enter a descriptive name for this pipe. You can use this to describe the pipe or your company may use a naming convention. It is not necessary to add any data to this field. If you do enter data here you can use this later to sort via the Lists. Status: For pipes there are three possible Status options. 1) On, 2) Off or Closed and 3) Ignore Pressure Loss. On: This is the normal position and tells the application that this pipe is open and to calculate the pressure loss in the line. Off or Closed: This means that the pipe is closed to flow. This means you can close pipes if you wish to isolate part of a network. Ignore Pressure Loss: This means that FluidFlow sees the pipe as open but does not make a pressure/friction loss calculation for this pipe, i.e., friction loss will be zero. Note, although a pipe status may be set to Ignore Pressure Loss, the software will still calculate any changes in flowing velocity, associated velocity pressure and resultant static pressure values. Length: This sets the length of the pipe. It is recommended that pipe lengths of "0" are avoided. In scenarios where you have fittings connected immediately together, the software requires that a short section of pipework is used. You can set this pipe to have a diameter which matches the diameter of the fittings and a short length such as 0.2 ft (0.2 M) etc. Note, the pressure loss across the short pipe for the most part, is negligible compared to the losses across the remainder of the system. If you wish, you can also set the Status of this pipe to "Ignore Pressure Loss" from the Input tab of the Data Palette. It is also recommended that any pipe lengths defined in a model are sufficient to overcome the elevation values defined for the connected upstream and downstream nodes. Length Unit: This refers to the unit you wish to use for entering the pipe length described above. Input units are never changed by the program, but you can get the program to change all output/result units. Geometry: For pipes, this entry describes the cross-sectional area profile of the pipe. Possible values are: Cylindrical; Rectangular/Square; Annular. If you select Rectangular/Square you can make pressure loss calculations on ductwork. Selecting Annular allows you to make pressure loss calculations on pipes with an annular (the region between two concentric circular cross sections). You should be aware that if this selection is changed the additional/changed rows appear in the Input Editor. For a Rectangular/Square selection the following rows appear: Figure 2: Additional rows/input data required for rectangular ducting. Rectangular Width: This row is used to enter the width of the duct. Rectangular Height: This row is used to enter the duct height. Width/Height Unit: This refers to the unit of length used for the above two entries. Max Op Pressure: If there is a maximum pressure rating of the ductwork you should enter this here. Leaving the value at 0 means that FluidFlow will not make an overpressure check. Pressure Unit: This refers to the unit of pressure used to specify the maximum operating pressure of the duct. For annular pipes the following rows appear: Figure 3: Additional rows/input data required for annular pipes. Annulus Inner Diameter: This is the outside diameter of the inner pipe. Annulus Outside Diameter: The inside diameter of the outer pipe. Diameter Unit: This refers to the unit of length used for the above two entries. Max Op Pressure: If there is a maximum pressure rating of the annular pipe you should enter this here. Leaving the value at 0 means that FluidFlow will not make an overpressure check. Pressure Unit: This refers to the unit of pressure used to specify the maximum operating pressure of the annular pipe. Use Database Size: The options for this entry are: Yes; No. Selecting Yes allows you to use pipe size information from the FluidFlow database of pipes. Selecting No allows you to enter pipe diameter data directly. Figure 1 shows the additional rows that define the database selection entries if Yes is selected. Nominal Size and Classification: These rows in the Input Editor work together. You cannot add a value directly into this row by typing an entry. Instead when you focus on this row a button appears at the right edge. This means the selection of pipe size and classification is made via the Set Pipe Dimension dialog. Remember that the pipe hierarchy is Material -> Size -> Classification, an example would be Steel -> 6" -> Schedule 40 If you select No to the Use Database Size entry then the following rows/input need to be completed. Figure 4: Additional rows/input data required for Use Database Size = No. Inside Diameter: This is the inside diameter of the pipe. Diameter Units: The units of length for the Inside Diameter and Pipe Wall Thickness entries. Wall Thickness: The wall thickness of the pipe. This property is used in heat loss calculations. Friction Model: The options for this entry are: 1) Moody 2) Hazen Williams, 3) Fixed Friction Factor & 4) Shell-MIT. Moody: Unless you have a specific engineering reason, you should leave this setting at Moody. This means that FluidFlow calculates friction factor according to the Moody Charts (in fact FluidFlow uses the Colebrook-White equation for estimating friction factor). Hazen Williams: These calculations are specific for water and are included to allow for fire system calculations according to NFPA (National Fire Protection Association) guidelines. If you are making a fire water calculation you can also use the Moody relationship as the NFPA guidelines do not preclude this option. If you decide to use Hazen Williams pressure loss relationships then additional input data is required. Figure 5: Additional row/input data required for Friction Model set to Hazen Williams. Hazen Williams Coeff: This is the value of C used in the Hazen Williams formula for pressure loss. Typical C factors used in design, which take into account some increase in pipe roughness as the pipe ages are: Cement Pipes - 140; Cast Iron Pipes - 100; Concrete Pipes - 100; Copper Pipes - 150; Steel Pipes - 120; Polyethylene Pipes - 150; Polyvinyl Chloride Pipes - 150; Fibre Reinforced plastic - 150. Careful consideration should be given to the selection of the correct Hazen Williams coefficient. For instance, a typical C factor for new unlined steel pipe is close to 140. However, it quickly deteriorates to 130 and after a few years of use, to 120. Conservative design can be built into systems by intentionally designing a lower Hazen Williams coefficient than that suggested for each of the pipe materials noted above. The Table below provides typical values for the H-W "C" Coefficient as documented in various design standards which can be used in the Hazen Williams equation.
Pipe or Tube | NFPA 13 (2007 Edition) | EN 12845 (2004 - 2009 Edition) | BS 9251
Unlined Cast Iron | 100 | 100 | ---
Unlined Ductile Iron | 100 | 110 | ---
Black Steel (Dry Systems including Preaction) | 100 | --- | ---
Black Steel (Wet Systems including Deluge) | 120 | 120 | 120
Galvanized (All) | 120 | 120 | ---
Plastic (All) | 150 | --- | 150
Cement-Lined Cast Iron | 140 | 130 | ---
Cement-Lined Ductile Iron | 140 | --- | ---
Copper Tube | 150 | 140 | 140
Stainless Steel Tube | 150 | 140 | ---
Asbestos Cement | 140 | --- | ---
Concrete | 140 | --- | ---
The above is for reference purposes. It is recommended that the designer reviews relevant publications in order to select the appropriate C factor for your design application. The publication titled "Handbook of Hydraulics (7th Edition), McGraw-Hill" also documents "C" Coefficient values for various pipe conditions as follows:
Type of Pipe | C Coefficient
Extremely Smooth and Straight | 140
Very Smooth | 130
New Riveted Steel | 110
Old Riveted Steel | 100
Old Cast Iron | 95
Old Pipes in Poor Condition | 60-80
Fixed Friction Factor: If this option is selected, then a row appears asking for the value you wish to use for friction factor. FluidFlow uses the Darcy friction factor and this is the value you should enter. Darcy friction factor is 4 times the Fanning Friction Factor. Note, fixing the friction factor is generally not a recommended modelling technique. Fixing friction factors should only be used in systems where experimental friction factors have been measured or have been back-calculated from plant measurements. It is also not appropriate to fix the friction factor when modelling settling slurry systems as the friction factor is the output of the modelling method used. Shell-MIT: When this option is selected, the software calculates the pipe friction loss according to the Shell-MIT equations. The solution approach uses a modified Reynolds Number. Using this modified Reynolds Number, the friction factor is calculated depending on whether the flow is laminar or turbulent. The Shell-MIT method is used in the calculation of pressure loss in heavy crude oil and heated liquid pipelines and as such, should be used only for such specific cases. It is not recommended that users select this pipe friction loss method for fluids other than that described herein. Use Database Roughness: The options for this entry are: Yes; No. Selecting yes allows you to use pipe roughness information from the FluidFlow database of roughness factors. Selecting No allows you to enter a pipe's absolute roughness directly. Figure 1 shows the additional rows that define the roughness selection entries if Yes is selected. Roughness Description: You cannot add a value directly into this row by typing an entry. Instead when you focus on this row a button appears at the right edge. This allows you to select a value from the roughness database via the Select Pipe Roughness dialog. Roughness values are stored for each pipe material and are attached to a description that has, perhaps more meaning than an absolute value. For example "Gas Pipes after several years use" is easier to understand than using the equivalent value of 0.14mm. If you select No to Use Database Roughness then Figure 6 shows the additional data entries that are required. Figure 6: Additional Row/input data required for Use Database Roughness set to No. Roughness: This is the absolute value in length units representing the average imperfections in the pipe surface. Typical values can be found in many literature sources. FluidFlow uses this roughness value in the calculation of pipe friction factor according to the Haaland equation. In flow calculations relative roughness (absolute roughness divided by the pipe inside diameter is the important criteria). Roughness Units: The unit of length used to define the pipe absolute roughness. Use Database Scaling: The possible values for this entry are: Yes; No. Selecting yes allows you to use pipe scaling information from the FluidFlow database of scaling factors. Selecting No allows you to enter a scaling value directly. Figure 1 shows the additional row that defines the scaling factor directly. Scaling: This is the reduction in pipe diameter, expressed as a percentage, that may occur over a time period. For example water pipes used without water treatment may scale by 10-12% after a period of 15 years use. Since pipe diameter is the single most significant factor in determining pressure loss it is often important to carry out pipe aging studies using this field. Scaling Description: You cannot add a value directly into this row by typing an entry. Instead when you focus on this row a button appears at the right edge. This allows you to select a value from the pipe scaling database via a dialog. Scaling values are stored for each pipe material and are attached to a description that has, perhaps more meaning than an absolute value. For example "Heavy Scaling" is easier to understand than using the equivalent value of a 15% reduction in inside pipe diameter. Sizing Model: The options for this entry are: 1) Economic Velocity 2) By Velocity and 3) By Pressure Gradient. FluidFlow allows you to automatically size a pipe or duct based on any of these three approaches. Note, when sizing ductwork using any of these three models, the software will calculate the required duct diameter. If you wish to develop a ductwork system with a rectangular geometry, you will need to determine the height and width of the duct required and enter these values into the Input tab of the Data Palette for each section of ductwork. There are various literature sources which provide tables of equivalent dimensions for circular ductwork, such as the ASHRAE Guides & CIBSE Guide C. Economic Velocity: By selecting this option, we are allowing the software to determine the exact pipe size corresponding to the calculated economic velocity (shown in the Result). The economic velocity is a function of the fluid physical properties, the pipe materials, various capital and installation costs and the operating hours/year. This value is calculated automatically by FluidFlow from the Generaux equation and the calculation uses the values and constants stored in the pipe sizing database. Economic velocity is changing (generally decreasing) with time, particularly as energy costs have increased rapidly in recent times. Flite Software keeps these values up to date, which is one of the many reasons you should keep your software current. Economic velocity is meant to be a guide for pipe sizing; it is NOT a strict criteria for sizing pipes. For example, you would not use this value to size pipes where two phase flow is present, or where plant operation is intermittent, or where materials can degrade at high velocities, or for Non-Newtonian flows. Note: The exact economic size is the exact pipe size corresponding to the economic velocity. Of course pipes are purchased in standard sizes and the exact economic size is meant to be available so that you can check pipe size at a glance. The caveats explained in the Economic Velocity description should be considered before blindly following this value. By Velocity: If you select "By Velocity" then Figure 7 shows the additional data entries that are required. Figure 7: Sizing Model - By Velocity. Design Velocity: This row is used to enter the design pipe/duct velocity. FluidFlow will automatically determine the exact pipe size corresponding to this velocity (shown in the Results as Exact Velocity Size). Velocity Unit: This refers to the unit of velocity used for the above entry. By Pressure Gradient: If you select "By Pressure Gradient" then Figure 8 shows the additional data entries that are required. Note: when selecting this option, the flow in the system must be a design condition, i.e., we cannot, in reality, size a pipeline using this option if only the inlet and outlet pressures are known. Figure 8: Sizing Model - By Pressure Gradient. Design Pressure Gradient: This describes the design rate-of-change in pressure across the length of pipe/duct. FluidFlow will automatically determine the exact pipe size corresponding to this gradient (shown in the Results as Exact Pressure Gradient Size). Pressure Gradient Unit: This refers to the unit of pressure gradient used for the above entry. Heat Loss Model: For pipes there are 5 possible options: 1) Ignore Heat Loss/Gain 2) Fixed Temperature Change 3) Fixed Transfer Rate 4) Do Heat Transfer Calculation and 5) Buried Pipe Calculation. Heat Loss Model - Option 1: Ignore Heat Loss/Gain is the default setting. This means that flow along the pipe is assumed to be adiabatic. Heat Loss Model - Option 2: Selecting Fixed Temperature Change allows you to specify a temperature change for the fluid as it flows down the pipe. Selecting Fixed Temperature Change adds additional rows to the Input Editor as shown in Figure 9. Note, when using the Fixed Temperature Change function, the software automatically determines the amount of heat energy transfer across the pipe. This result is then displayed in the Results table for the pipe. The Inside Film Coefficient, Pipe Wall Coefficient, Insulation Coefficient, Outside Film Coefficient or Overall HT Coefficient are not available to view in the Results Table when using this selection. Figure 9: Additional input data required for Heat Loss Model set to Fixed Temperature Change. Heat Transfer Direction: This value can either be: Out of Network; or Into Network. Out of Network means that heat is lost from the fluid. This has the effect of a temperature drop in the fluid as it flows along the pipe. Into Network means that the temperature of the fluid is increased as the fluid flows along the pipe. Temperature Change: Use this row to specify the temperature change that occurs as the fluid flows down the pipe. The heat transfer direction setting determines if temperature is increased or decreased. FluidFlow adjusts fluid physical properties along the pipe as the temperature changes and also calculates the total amount of heat that needs to be transferred for the specified temperature change to occur. You should be aware that NO check is made to determine if this temperature change is possible, i.e., can this temperature change actually occur? You can think of this mathematically as FluidFlow makes the calculation Heat Transferred = Mass Flow * Specific Heat * Temperature Change, but does not make the calculation Heat Transferred = Heat Transfer Coefficient * Heat Transfer Area * Log Mean Temperature Driving Force. If you specify a temperature that means a change of phase state you will NOT obtain accurate results unless you have the two-phase module activated, instead you will get a warning and the friction loss calculation will be made according to the upstream phase state. Temperature Unit: The unit of temperature used to specify the temperature change. Heat Loss Model - Option 3: Fixed Transfer Rate allows you to specify a fixed amount of heat to be either taken out of or added to the fluid as it flows along the pipe. Selecting Fixed Transfer Rate can be conceptualized as the converse of selecting Fixed temperature Change. As before additional rows appear in the Input Editor as shown in Figure 10. Note, when using the Fixed Transfer Rate function, the software automatically determines the temperature change across the pipe element. This result is then displayed in the Results table for the pipe. The Inside Film Coefficient, Pipe Wall Coefficient, Insulation Coefficient, Outside Film Coefficient or Overall HT Coefficient are not available to view in the Results Table when using this selection. Figure 10: Additional input data required for Heat Loss Model set to Fixed Transfer Rate. Heat Transferred: Allows you to specify the quantity of heat transferred to (or from) a pipe. This row works in relation with the Heat Transfer Direction Setting to determine the direction of heat flow. FluidFlow adjusts fluid physical properties along the pipe as the heat transfer occurs and also calculates the total temperature change that will occur. You should be aware that NO check is made to determine if this heat transfer is possible. You can think of this mathematically as FluidFlow makes the calculation Heat Transferred = Mass Flow * Specific Heat * Temperature Change, but does not make the calculation Heat Transferred = Heat Transfer Coefficient * Heat Transfer Area * Log Mean Temperature Driving Force. If you specify a heat transferred quantity that means a change of phase state occurs, you will NOT obtain accurate results unless you have the two-phase module activated, instead you will get a warning and the friction loss calculation will be made according to the upstream phase state. Heat Transfer Unit: The unit of heat transferred quantity that is used to specify the heat transferred to or from the fluid as it flows along the pipe. Heat Loss Model - Option 4: Do Heat Loss Calculation, means that FluidFlow will make a full heat loss calculation. You can also specify insulation properties if this selection is made. Selecting Do Heat Loss Calculation adds additional rows to the Input Editor as shown in Figure 9. Note, when using the Do Heat Loss Calculation model in conjunction with the Calculate U Value function, the software automatically calculates the Inside Film Coefficient, Pipe Wall Coefficient, Insulation Coefficient, Outside Film Coefficient & Overall HT Coefficient on the basis of the design inputs for the rows shown in Figure 11. The calculated results for these parameters are displayed in the Results Table for the pipe. When we use the Do Heat Loss Calculation model in conjunction with the Input U Value function, the software automatically determines the temperature change and energy transfer across the pipe element. These results are then displayed in the Results table for the pipe. The Inside Film Coefficient, Pipe Wall Coefficient, Insulation Coefficient or Outside Film Coefficient are not available to view in the Results Table when using this selection. Figure 11: Additional input data required for Heat Loss Model Set to Do Heat Loss Calculation. Heat Transfer Coeff (U Value): There are two possible values: Calculate U Value; Input U Value. If Calculate U Value is selected, the user will need to define the values for each row as shown in Figure 9. Refer to Figure 10 below for further information on selecting the option Input U Value. Use Insulation: There are two possible values: Yes; No. If Yes is selected then the additional rows needed to fully specify the insulation material and thickness appear as shown in Figure 9. Insulation Type: You cannot add a value directly into this row by typing an entry. Instead when you focus on this row a button appears at the right edge. This allows you to select an insulation material from the pipe insulation database via the Select Pipe Insulation dialog. Insulation materials are stored together with their thermophysical properties as a function of temperature. Insulation Thickness: This is the thickness of insulation that will be used to cover the pipe. Insulation Thickness Unit: The unit of length that is used to specify the insulation thickness. Local Ambient Temperature: This value represents the local temperature of the outside air. Heat Loss calculations take into account conduction, convection and radiation losses. The heat loss calculation assumes that the pipes are exposed to air. Note, you cannot use this calculation to estimate heat loss for buried pipe scenarios without losing accuracy. Temperature Unit: The unit of temperature for the local ambient air. Surface Emissivity: The value of emissivity for the insulation material (or cladding) if this is used. Typical values for Aluminium cladding are 0.8 for polished aluminium to 0.4 for oxidized aluminium. Iron 0.6. Stainless 0.35. Local Wind Speed: This is the local wind speed of the ambient air. The value is used in the calculation of the convection coefficient. Speed Unit: The unit of speed used for the local wind speed. Selecting Input U Value for the Heat Transfer Coeff (U Value) field adds additional rows to the Input Editor as shown in Figure 12: Figure 12: Additional input data required when Heat Transfer Coeff (U Value) is set to Input U Value. Use Insulation: There are two possible values: Yes; No. If Yes is selected then we must define the insulation thickness. Insulation Thickness: This is the thickness of insulation that will be used to cover the pipe. This allows the software to determine the overall outer diameter of the pipe and insulation combined. Insulation Thickness Unit: The unit of length that is used to specify the insulation thickness. Local Ambient Temperature: This value represents the local temperature of the outside air. Heat Loss calculations take into account conduction, convection and radiation losses. The heat loss calculation assumes that the pipes are exposed to air. Note, you cannot use this calculation to estimate heat loss for buried pipe scenarios without losing accuracy. Temperature Unit: The unit of temperature for the local ambient air. Overall Ht Transfer Coeff: The overall heat transfer coefficient for a pipe is obtained from the individual resistances. Typically resistances can be inside film, pipe wall, pipe insulation, anti-corrosion coatings, anti-buoyancy concrete, surrounding earth, outside film, etc. Typical overall heat transfer coefficients can be found in many literature sources, and depend on pipe size, buried material, soil moisture (or subsea currents), etc. Heat Loss Model - Option 5: Buried Pipe Calculation allows you to perform heat transfer calculations which take into account local ground conditions. Selecting Buried Pipe Calculation adds additional rows to the Input Editor as shown in Figure 13. When we use the Buried Pipe Calculation function, the software automatically determines the temperature change and energy transfer across the pipe element. These results are then displayed in the Results table for the pipe. TheInside Film Coefficient, Pipe Wall Coefficient, Insulation Coefficient or Outside Film Coefficient are not available to view in the Results Table when using this selection. You can however view the Overall HT Coefficient for the element in the Results table. Figure 13: Additional input data required for Heat Loss Model Set to Buried Pipe Calculation. Use Pipe Coating: No is the default setting. Figure 14 outlines the additional data entries that are required if we select Yes. Figure 14: Additional input data required when the option Use Pipe Coating is set to Yes. Pipe Coating Type: You cannot add a value directly into this row by typing an entry. Instead when you focus on this row a button appears at the right edge. This allows you to select a value from the pipe insulation database. Pipe Coating Thickness: This is the thickness of coating that will be used to cover the pipe. Use Pipe Insulation: No is the default setting. Figure 15 outlines the additional data entries that are required if we select Yes. Figure 15: Additional input data required when the option Use Pipe Insulation is set to Yes. Pipe Insulation Type: You cannot add a value directly into this row by typing an entry. Instead when you focus on this row a button appears at the right edge. This allows you to select an insulation material from the pipe insulation database via the Select Pipe Insulation dialog. Insulation material are stored together with their thermophysical properties as a function of temperature. Pipe Insulation Thickness: This is the thickness of insulation that will be used to cover the pipe. Use Pipe Backfill: No is the default setting. Figure 16 outlines the additional data entries that are required if we select Yes. Figure 16: Additional input data required when the option Use Pipe Backfill is set to Yes. Pipe Backfill Type: You cannot add a value directly into this row by typing an entry. Instead when you focus on this row a button appears at the right edge. This allows you to select a value from the database. Pipe Backfill Thickness: This is the thickness of backfill that will be used around the pipe. Buried Depth to Pipe Center: This is the distance from the ground surface to the pipe centerline. Thickness/Depth Units: The unit of length that is used when specifying the thickness/depth. Soil Type: You cannot add a value directly into this row by typing an entry. Instead when you focus on this row a button appears at the right edge. This allows you to select a soil type from the database. Figure 17 shows the default settings for this row. Figure 17: Soil Type. Average Soil Temperature: This is the average annual temperature condition of the soil local to the pipe. Temperature Unit: The unit of temperature for the local soil condition. User-Defined Fields: Draw Thickness: This value represents the thickness that the pipe is drawn in the flowsheet. It has no effect on any calculation. You can use this feature to emphasize your flowsheet. This can be particularly useful when used together with the pipe color. Draw Color: This row in the Input Editor allows you to change the color that the pipe is drawn in the flowsheet. You can select the color from the standard windows color picker dialog. User-Defined Fields: Allows you to add "fields" to the element, for use in, for example, scripting or reporting. Clicking on the input will display the User-Defined Fields dialog to add/edit/delete fields. Properties On Flowsheet: This value can either be: Show or Hide. The Properties on Flowsheet row is available for all components. This means that you can decide what properties you wish to show on the flowsheet and for which components. If Show is selected then additional rows appear in the Input Editor, which allow you to set text font, color, size, text position and the properties you wish to display. The additional rows are shown in Figure 18: Figure 18: Additional input data required for showing properties on the flowsheet. Alignment: This row controls the alignment of the component properties on-screen. Possible values are: Top, Bottom, Left, or Right. Alignment of the displayed text is relative to the center of the component. Font: Text font properties can be set from the standard windows font dialog. Properties: Shows/hides Input and Result fields for display of properties on flowsheet. This allows for visibility of any input or calculated/result data to be controlled for each component. Individual property setting is made via the Select Element Properties dialog.