IPE-TM-510 Hydraulics
Typical Pump Spillback Hydraulics P9.8
IPE-TM-510-12
1. Table of Contents
1. Table of Contents 1
2. Purpose 1
3. Determine Pump Minimum Flow Protection Requirements 1
4. Normal Flow for All Process Cases Exceeds Pump Minimum Flow 2
5. Column Total Overhead Pump with Minimum Flow Protection via Reflux 6
APPENDIX A 12
APPENIDX B 13
- Other related Procedures for reference:
- IPE-TM-510-13, “Typical Pump Spillback Circuits in NHP”
- IPE-TM-510-14, “Nontypical Pump Spillback Circuits in P9.8 Hydraulics”
- IPE-TM-510-15, “Nontypical Pump Spillback Circuits in NHP”
2. Purpose
This procedure demonstrates the proper method of setting up the most common hydraulic circuits in P9.8 for pump minimum flow protection. In the hydraulic tabulations, for all flow scenarios in all process cases, the pump head and system frictional losses between the upstream vessel and spillback/splitter node must be based on a flow no lower than the minimum continuous flow of the pump.
- A number of important factors must be considered by the Instrument Engineer when specifying a control valve. These factors include (but are not limited to): valve body size, commercially available rated valve coefficient (Cv), characteristic (linear or equal percentage), and metallurgy of control valve internals. For the Instrument Engineer to confidently specify a control valve, the hydraulic tabulations must reflect the true rangability of the control valve.
3. Determine Pump Minimum Flow Protection Requirements
Tool (see Appendix A and B for graphical decision trees) shall be used to determine whether a pump requires minimum flow protection. If the Design Engineer concludes that pump minimum flow protection is required, the tool will indicate the section number and procedure number that shall be used as a guide to ensure that the hydraulic circuits are set up properly. All the simulation and flow scenario factors are calculated in Tool T-510-04, “Factors and Spillback Requirements for P98 Hydraulics”. The only required input to the tool is the pump minimum flow, normal process flows and specific gravity.
4. Normal Flow for All Process Cases Exceeds Pump Minimum Flow
This example involves a pump with a single discharge flow path and multiple process cases. At the normal flow scenario for each process case, the flow exceeds the minimum continuous flow of the pump and the spillback flow control valve is closed. At the alternate flow scenario of the lowest process flow case, the flow is less than the minimum continuous flow of the pump. An automated spillback is required where the spillback flow controller adjusts the opening of the spillback flow control valve until the flow through the pump equals or exceeds the minimum continuous flow. For the alternate flow scenario of the lowest process flow case, the flow through the pump and spillback control valve is equal to the minimum flow of the pump. If the forward flow control valve ever closes (due to a localized instrument air failure, for example), the spillback flow control valve must be capable of passing the minimum continuous flow of the pump.
The Design Engineer shall adhere to the following (see Example 4 hydraulic tabulations):
- A flow meter on the pump discharge and a spillback splitter shall be added to the circuit which contains the pump.
- A spillback circuit shall be created. This circuit runs after the circuit which contains the pump. This circuit shall start at the spillback node, proceed through a control valve, and end at a nozzle on the vessel which provides suction to the pump. In column bottoms services, the spillback circuit can discharge into the reboiler inlet piping. In general, the spillback flow should not return to the suction piping immediately upstream of the pump.
- The simulation, design flow scenario and alternate flow scenario factors for the pipes are calculated by Tool T-510-04 and shall be applied accordingly. For the net forward circuit, enter the normal, design and alternate flow scenario factors for the circuit consistent with line 5. For the spillback circuit, the normal and alternate flow scenario should be set to 100%.
- The Instrument Engineer shall include the alternate flow scenario of the lowest process flow case on the sheet in the 616 Project Specification that corresponds to the forward flow control valve.
- In the 616 Project Specification, the Instrument Engineer shall base the sizing of the spillback flow control valve on the alternate flow scenario of the lowest process flow case.
From Tool :
Example 4 Hydraulics of Pump with Single Discharge Flow Path and Minimum Flow Protection via Control Valve
ANY CLIENT Note - the information in this document is Page
XXXXXX PROJECT confidential and the property of Inflection Point Engineering, and Date
ANY CITY, STATE must not be disclosed to others or reproduced in Proj
COUNTRY any manner or used for any purpose whatsoever By
SINGLE DISCHARGE – S/B WITH CV – CASE 1 without its written permission. EFID
Circuit 1: FRESH FEED Case Design Case Alternate
Press 100.0% 110.0% 60.0%
Drop --------------- --------------- ---------------
Line 100 Per Nozl Press Inlet Press Inlet Press Inlet
Size Eq 100ft Elev Drop Press Drop Press Drop Press
Equipment Identification in ft psi ft psi psig psi psig psi psig
FEED SURGE DRUM 10 29.0 29.0 29.0
Liquid Level 0 -0.15 29.0 -0.15 29.0 -0.15 29.0
Line 1 (Alter%= 87.2) 8 3.7 0.09 0.32 29.1 0.39 29.1 0.25 29.1
Static Head 7 -2.19 28.8 -2.19 28.8 -2.19 28.9
CHARGE PUMP *Gov* 2 -486.4 31.0 -466.5 30.9 -509.1 31.1
Pump head, feet 1641.7 1574.6 1718.5
Pump capacity, gpm 439 483 383
Flowing Specific Gravity 0.684
Operating Temperature, degF 201
Viscosity, cp 0.27
Line 3 (Alter%= 87.2) 6 3.3 0.35 1.14 517.4 1.38 497.4 0.88 540.2
CHARGE PUMP SPILLBACK FE(1701) 6 1.49 516.3 1.80 496.0 0.24 539.3
Line 4 (Alter%= 87.2) 6 .47 0.35 0.17 514.8 0.20 494.2 0.13 539.1
CHARGE PUMP SPILLBACK SPLIT POINT 514.6 494.0 539.0
Line 5 6 .47 0.35 0.17 514.6 0.20 494.0 0.03 539.0
FRESH FEED ORIFICE FE(1702) 6 1.49 514.4 1.80 493.8 0.24 538.9
Line 20 6 1.7 0.35 0.58 512.9 0.70 492.0 0.09 538.7
FRESH FEED CV(1602) 49.52 512.4 10.02 491.3 95.70 538.6
Line 21 6 2.4 0.35 0.84 462.9 1.02 481.3 0.13 442.9
FRESH FEED ADDITION POINT 462.0 480.3 442.8
Circuit 2: CHARGE PUMP MINIMUM FLOW SPILLBACK Case Design Case Alternate
Press 100.0% .0% 100.0%
Drop --------------- --------------- ---------------
Line 100 Per Nozl Press Inlet Press Inlet Press Inlet
Size Eq 100ft Elev Drop Press Drop Press Drop Press
Equipment Identification in ft psi ft psi psig psi psig psi psig
CHARGE PUMP SPILLBACK SPLIT POINT 514.6 539.0
Line 8 (Flow %= 87.2) 6 2.4 0.27 0.65 514.6 0.65 539.0
CHARGE PUMP SPILLBACK CV(1601) 481.90 514.0 506.25 538.3
Line 9 (Flow %= 87.2) 6 2.4 0.27 0.65 32.1 0.65 32.1
Static Head 10 2.23 31.4 2.23 31.4
Liquid Level 0 0.15 29.2 0.15 29.2
FEED SURGE DRUM 10 29.0 29.0
Example 4 (continued)
ANY CLIENT Note - the information in this document is Page
XXXXXX PROJECT confidential and the property of Inflection Point Engineering, and Date
ANY CITY, STATE must not be disclosed to others or reproduced in Proj
COUNTRY any manner or used for any purpose whatsoever By
SINGLE DISCHARGE – S/B WITH CV – CASE 2 without its written permission. EFID
Circuit 1: FRESH FEED Case Design Case Alternate
Press 100.0% 110.0% 60.0%
Drop --------------- --------------- ---------------
Line 100 Per Nozl Press Inlet Press Inlet Press Inlet
Size Eq 100ft Elev Drop Press Drop Press Drop Press
Equipment Identification in ft psi ft psi psig psi psig psi psig
FEED SURGE DRUM 10 29.0 29.0 29.0
Liquid Level 0 -0.15 29.0 -0.15 29.0 -0.15 29.0
Line 1 (Alter%= 87.2) 8 3.7 0.09 0.32 29.2 0.38 29.2 0.24 29.2
Static Head 7 -2.23 28.8 -2.23 28.8 -2.23 28.9
CHARGE PUMP 2 -500.0 31.1 -480.7 31.0 -521.1 31.1
Pump head, feet 1653.8 1589.3 1723.6
Pump capacity, gpm 430 473 375
Flowing Specific Gravity 0.698
Operating Temperature, degF 212
Viscosity, cp 0.27
Line 3 (Alter%= 87.2) 6 3.3 0.34 1.12 531.1 1.35 511.7 0.86 552.2
CHARGE PUMP SPILLBACK FE(1701) 6 1.46 530.0 1.77 510.4 0.23 551.3
Line 4 (Alter%= 87.2) 6 .47 0.34 0.16 528.5 0.20 508.2 0.13 551.1
CHARGE PUMP SPILLBACK SPLIT POINT 528.4 508.0 551.0
Line 5 6 .47 0.34 0.16 528.4 0.20 508.0 0.03 551.0
FRESH FEED ORIFICE FE(1702) 6 1.46 528.2 1.77 507.8 0.23 551.0
Line 20 6 1.7 0.34 0.56 526.7 0.68 506.0 0.09 550.8
FRESH FEED CV(1602) 69.56 526.2 28.33 505.3 125.90 550.7
Line 21 6 2.4 0.34 0.82 456.6 0.99 477.0 0.13 424.8
FRESH FEED ADDITION POINT 455.8 476.0 424.7
Circuit 2: CHARGE PUMP MINIMUM FLOW SPILLBACK Case Design Case Alternate
Press 100.0% .0% 100.0%
Drop --------------- --------------- ---------------
Line 100 Per Nozl Press Inlet Press Inlet Press Inlet
Size Eq 100ft Elev Drop Press Drop Press Drop Press
Equipment Identification in ft psi ft psi psig psi psig psi psig
CHARGE PUMP SPILLBACK SPLIT POINT 528.4 551.0
Line 8 (Flow %= 87.2) 6 2.4 0.27 0.64 528.4 0.64 551.0
CHARGE PUMP SPILLBACK CV(1601) 495.57 527.8 518.30 550.4
Line 9 (Flow %= 87.2) 6 2.4 0.27 0.64 32.1 0.64 32.1
Static Head 10 2.23 31.4 2.23 31.4
Liquid Level 0 0.15 29.2 0.15 29.2
FEED SURGE DRUM 10 29.0 29.0
5. Column Total Overhead Pump with Minimum Flow Protection via Reflux
This example involves a column total overhead pump with multiple process cases. At the normal (100%) flow scenario for each process case, the process flow exceeds the minimum continuous flow of the pump. An automated spillback is not required in column total overhead liquid service when – for all process cases – the sum of the normal (100%) reflux flow and turndown flow of net overhead liquid exceeds the minimum continuous flow of the pump.
The Design Engineer shall adhere to the following (see Example 5 hydraulic tabulations):
- The simulation, design flow scenario and alternate flow scenario factors for the pipes are calculated by Tool T-510-04 and shall be applied accordingly. Make sure that all lines in the reflux circuit between the splitter and the return to the fractionator have the same alternate flow scenario factor as line 5.
- Both the reflux and net overhead circuits shall include the pump. This ensures that sufficient differential pressure will be available to both the reflux and net overhead flow control valves.
From Tool :
Example 5 Hydraulics of Column Total Overhead Pumps with Minimum Flow Protection via Reflux
ANY CLIENT Note - the information in this document is Page
XXXXXX PROJECT confidential and the property of Inflection Point Engineering, and Date
ANY CITY, STATE must not be disclosed to others or reproduced in Proj
COUNTRY any manner or used for any purpose whatsoever By
COLUMN OVERHEAD – NO S/B WITH CV CASE CASE 1 without its written permission. EFID
Circuit 31: TOLUENE COLUMN NET OVERHEAD Case Design Case Alternate
Press 100.0% 110.0% 60.0%
Drop --------------- --------------- ---------------
Line 100 Per Nozl Press Inlet Press Inlet Press Inlet
Size Eq 100ft Elev Drop Press Drop Press Drop Press
Equipment Identification in ft psi ft psi psig psi psig psi psig
TOLUENE COLUMN RECEIVER 22 40.0 36.9 49.6
Liquid Level 2 -0.48 40.0 -0.48 36.9 -0.48 49.6
Line 1 (Alter%= 66.3) 12 5.3 0.09 0.47 40.5 0.56 37.3 0.21 50.1
Static Head 19 -6.05 40.0 -6.05 36.8 -6.05 49.9
TOLUENE COLUMN OVERHEAD PUMPS 3 -107.9 46.1 -104.5 42.8 -116.7 55.9
Pump head, feet 344.5 333.85 372.92
Pump capacity, gpm 1261 1387 836
Flowing Specific Gravity 0.723
Operating Temperature, degF 328
Viscosity, cp 0.20
Line 2 (Alter%= 66.3) 8 3.4 0.70 2.39 153.9 2.89 147.3 1.05 172.7
REFLUX + NET OVERHEAD SPLITTER 3 151.5 144.4 171.6
Line 6 3 .63 0.36 0.23 151.5 0.27 144.4 0.08 171.6
Static Head 37 11.62 151.3 11.62 144.2 11.62 171.5
TOLUENE PRODUCT COOLER 40 4.00 139.7 4.84 132.6 1.44 159.9
Line 321 3 2.2 0.33 0.73 135.7 0.88 127.7 0.26 158.5
Static Head 35 -12.76 135.0 -12.76 126.8 -12.76 158.2
TOLUENE PRODUCT TRIM COOLER 5 4.00 147.7 4.84 139.6 1.44 171.0
Line 322 3 2.2 0.33 0.73 143.7 0.89 134.8 0.26 169.5
Static Head 5 -1.84 143.0 -1.84 133.9 -1.84 169.3
TOLUENE COLUMN NET OVHD FE(1733) 3 1.75 144.8 2.12 135.7 0.63 171.1
Line 323 3 1.1 0.33 0.37 143.1 0.45 133.6 0.13 170.5
TOLUENE COLUMN NET OHD CV(1673) 120.81 142.7 110.84 133.2 149.68 170.4
Line 324 3 5.7 0.33 1.91 21.9 2.31 22.3 0.69 20.7
TOLUENE COLUMN OVERHEAD B.L. 20.0 20.0 20.0
Example 5 (Continued)
ANY CLIENT Note - the information in this document is Page
XXXXXX PROJECT confidential and the property of Inflection Point Engineering, and Date
ANY CITY, STATE must not be disclosed to others or reproduced in Proj
COUNTRY any manner or used for any purpose whatsoever By
COLUMN OVERHEAD – NO S/B WITH CV CASE CASE 1 without its written permission. EFID
Circuit 32: TOLUENE COLUMN REFLUX Case Design Case Alternate
Press 100.0% 110.0% 60.0%
Drop --------------- --------------- ---------------
Line 100 Per Nozl Press Inlet Press Inlet Press Inlet
Size Eq 100ft Elev Drop Press Drop Press Drop Press
Equipment Identification in ft psi ft psi psig psi psig psi psig
TOLUENE COLUMN RECEIVER 22 40.0 36.9 49.6
Liquid Level 2 -0.48 40.0 -0.48 36.9 -0.48 49.6
Line 1 (Alter%= 66.3) 12 5.3 0.09 0.47 40.5 0.56 37.3 0.21 50.1
Static Head 19 -6.05 40.0 -6.05 36.8 -6.05 49.9
TOLUENE COLUMN OVERHEAD PUMPS 3 -107.9 46.1 -104.5 42.8 -116.7 55.9
Pump head, feet 344.5 333.85 372.92
Pump capacity, gpm 1261 1387 836
Flowing Specific Gravity 0.723
Operating Temperature, degF 328
Viscosity, cp 0.20
Line 2 (Alter%= 66.3) 8 3.4 0.70 2.39 153.9 2.89 147.3 1.05 172.7
REFLUX + NET OVERHEAD SPLITTER 3 151.5 144.4 171.6
Line 5 (Alter%= 69.3) 8 2.4 0.32 0.77 151.5 0.93 144.4 0.37 171.6
Static Head 3 -0.94 150.8 -0.94 143.5 -0.94 171.3
TOLUENE COLUMN REFLUX FE(1732) 8 1.08 151.7 1.31 144.5 0.39 172.2
Line 315 (Alter%= 69.3) 8 2.4 0.32 0.77 150.6 0.93 143.2 0.37 171.8
TOLUENE COLUMN REFLUX CV(1672) 32.73 149.9 24.79 142.2 55.03 171.4
Line 316 (Alter%= 69.3) 8 4.3 0.32 1.40 117.1 1.70 117.4 0.67 116.4
Static Head 194 60.74 115.7 60.74 115.7 60.74 115.7
TOLUENE COLUMN 194 55.0 55.0 55.0
Example 5 (Continued)
ANY CLIENT Note - the information in this document is Page
XXXXXX PROJECT confidential and the property of Inflection Point Engineering, and Date
ANY CITY, STATE must not be disclosed to others or reproduced in Proj
COUNTRY any manner or used for any purpose whatsoever By
COLUMN OVERHEAD – NO S/B WITH CV CASE CASE 2 without its written permission. EFID
Circuit 31: TOLUENE COLUMN NET OVERHEAD Case Design Case Alternate
Press 100.0% 110.0% 60.0%
Drop --------------- --------------- ---------------
Line 100 Per Nozl Press Inlet Press Inlet Press Inlet
Size Eq 100ft Elev Drop Press Drop Press Drop Press
Equipment Identification in ft psi ft psi psig psi psig psi psig
TOLUENE COLUMN RECEIVER 22 40.0 36.9 49.6
Liquid Level 2 -0.48 40.0 -0.48 36.9 -0.48 49.6
Line 1 (Alter%= 66.3) 12 5.3 0.11 0.60 40.5 0.72 37.3 0.26 50.1
Static Head 19 -6.05 39.9 -6.05 36.6 -6.05 49.8
TOLUENE COLUMN OVERHEAD PUMPS *Gov* 3 -103.4 45.9 -99.13 42.7 -114.8 55.9
Pump head, feet 330.1 316.64 366.62
Pump capacity, gpm 1429 1572 948
Flowing Specific Gravity 0.723
Operating Temperature, degF 328
Viscosity, cp 0.20
Line 2 (Alter%= 66.3) 8 3.4 0.90 3.06 149.3 3.70 141.8 1.34 170.6
REFLUX + NET OVERHEAD SPLITTER 3 146.2 138.1 169.3
Line 6 3 .63 0.36 0.23 146.2 0.27 138.1 0.08 169.3
Static Head 37 11.62 146.0 11.62 137.8 11.62 169.2
TOLUENE PRODUCT COOLER 40 4.00 134.4 4.84 126.2 1.44 157.6
Line 321 3 2.2 0.33 0.73 130.4 0.88 121.4 0.26 156.2
Static Head 35 -12.76 129.7 -12.76 120.5 -12.76 155.9
TOLUENE PRODUCT TRIM COOLER 5 4.00 142.4 4.84 133.2 1.44 168.7
Line 322 3 2.2 0.33 0.73 138.4 0.89 128.4 0.26 167.2
Static Head 5 -1.84 137.7 -1.84 127.5 -1.84 167.0
TOLUENE COLUMN NET OVHD FE(1733) 3 1.75 139.5 2.12 129.4 0.63 168.8
Line 323 3 1.1 0.33 0.37 137.8 0.45 127.2 0.13 168.2
TOLUENE COLUMN NET OHD CV(1673) 115.51 137.4 104.48 126.8 147.35 168.0
Line 324 3 5.7 0.33 1.91 21.9 2.31 22.3 0.69 20.7
TOLUENE COLUMN OVERHEAD B.L. 20.0 20.0 20.0
Example 5 (Continued)
ANY CLIENT Note - the information in this document is Page
XXXXXX PROJECT confidential and the property of Inflection Point Engineering, and Date
ANY CITY, STATE must not be disclosed to others or reproduced in Proj
COUNTRY any manner or used for any purpose whatsoever By
COLUMN OVERHEAD – NO S/B WITH CV CASE CASE 2 without its written permission. EFID
Circuit 32: TOLUENE COLUMN REFLUX Case Design Case Alternate
Press 100.0% 110.0% 60.0%
Drop --------------- --------------- ---------------
Line 100 Per Nozl Press Inlet Press Inlet Press Inlet
Size Eq 100ft Elev Drop Press Drop Press Drop Press
Equipment Identification in ft psi ft psi psig psi psig psi psig
TOLUENE COLUMN RECEIVER 22 40.0 36.9 49.6
Liquid Level 2 -0.48 40.0 -0.48 36.9 -0.48 49.6
Line 1 (Alter%= 66.3) 12 5.3 0.11 0.60 40.5 0.72 37.3 0.26 50.1
Static Head 19 -6.05 39.9 -6.05 36.6 -6.05 49.8
TOLUENE COLUMN OVERHEAD PUMPS *Gov* 3 -103.4 45.9 -99.13 42.7 -114.8 55.9
Pump head, feet 330.1 316.64 366.62
Pump capacity, gpm 1429 1572 948
Flowing Specific Gravity 0.723
Operating Temperature, degF 328
Viscosity, cp 0.20
Line 2 (Alter%= 66.3) 8 3.4 0.90 3.06 149.3 3.70 141.8 1.34 170.6
REFLUX + NET OVERHEAD SPLITTER 3 146.2 138.1 169.3
Line 5 (Alter%= 69.3) 8 2.4 0.40 0.95 146.2 1.15 138.1 0.46 169.3
Static Head 3 -0.94 145.3 -0.94 136.9 -0.94 168.8
TOLUENE COLUMN REFLUX FE(1732) 8 1.35 146.2 1.63 137.9 0.48 169.8
Line 315 (Alter%= 69.3) 8 2.4 0.40 0.95 144.9 1.15 136.3 0.46 169.3
TOLUENE COLUMN REFLUX CV(1672) 26.45 143.9 17.25 135.1 52.27 168.8
Line 316 (Alter%= 69.3) 8 4.3 0.40 1.74 117.5 2.11 117.8 0.84 116.6
Static Head 194 60.73 115.7 60.73 115.7 60.73 115.7
TOLUENE COLUMN 194 55.0 55.0 55.0
APPENDIX A
DECISION TREE A - Automated Pump Spillbacks
APPENIDX B
DECISION TREE B - Automated Spillbacks Associated with Column Total Overhead Pumps
© 2026 Inflection Point Engineering, LLC. All rights reserved. The content of this page — including calculation methods, reference data, written analysis, interactive tools, and source code — is the intellectual property of Inflection Point Engineering, LLC and is protected under applicable copyright, trademark, and trade secret laws. Unauthorized reproduction, redistribution, modification, or derivative use in whole or in part is prohibited without prior written consent.
Disclaimer. This material is provided for informational and educational purposes only and does not constitute professional engineering advice. Calculations, reference data, and methodologies are based on published standards and accepted engineering practice but are not a substitute for engineering judgment, site-specific analysis, or review by a licensed Professional Engineer. Inflection Point Engineering, LLC makes no warranties, express or implied, regarding the accuracy, completeness, or fitness for a particular purpose of any content presented here, and shall not be liable for any direct, indirect, incidental, or consequential damages arising from its use. Users assume all risk associated with applying this content to real-world design, operations, or decisions.
© 2026 Inflection Point Engineering, LLC. All rights reserved.