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Steam Modules

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CALCULATOR MODULE : ASME B31.1 Power Piping Line Pipe Schedule   ±

Calculate ASME B31.1 power piping schedule for metal and plastic piping.

Calculate the piping minimum wall thickness and hoop stress wall thickness schedule from the nominal wall thickness, fabrication tolerance and corrosion allowance.

`tm = tn - fa `
`tm = (1 - fx) tn `
`t = tm - c `

where :

tn = nominal wall thickness
tm = minimum wall thickness
t = hoop stress wall thickness
c = corrosion thickness allowance
fa = negative fabrication thickness allowance
fx = negative fabrication fraction

The minimum wall thickness equals the nominal wall thickness minus the fabrication allowance. The pressure containment wall thickness equals the nominal wall thickness minus the fabrication tolerance, and minus the corrosion allowance. Fabrication tolerance can be defined by either a fabrication allowance, or a fabrication fraction. The pipe diameter can be defined by either the outside diameter or the inside diameter. Use the Result Table option to display a table of pipe dimensions versus wall thickness, wall tolerance, or piping diameter for metal pipes, or pipe dimension versus wall thickness for plastic pipes.

Calculate metal piping maximum and minimum diameter schedule. Use the Result Table option to display a table of pipe dimensions versus wall thickness, wall tolerance, or piping diameter.

Calculate piping unit mass and joint mass schedule for metal and plastic piping. Use the Result Table option to display a table of pipe dimensions and mass versus wall thickness.

Calculate piping tensile stress, yield stress and allowable schedule for metal piping. Use the Result Table option to display a table of stress versus material type.

Plastic pipe wall thickness can be defined by wall thickness or diameter ratio (DR or IDR). Select standard diameter ratios from the plastic pipe schedule (SDR or SIDR), or use user defined diameter ratios (DR or IDR).

Reference : ANSI/ASME B31.1 : Power Piping (2014)

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CALCULATOR MODULE : ASME B31.1 Power Piping Allowable Stress   ±

Calculate ASME B31.1 power piping basic allowable stress (S), allowable stress (SE), design stress (SEW), tensile stress (SUT), and yield stress (SYT) from the design temperature (US units).

The allowable stress (SE) is calculated from tables A-1 to A-10. The calculated stress values are constant for temperatures below the data range. For temperatures above the data range, the stress values can be calculated as either a constant value from the highest data point, constant slope from the highest data point, or set to zero. Stress values for temperatures above the data range should be ued carefully (engineering judgement is required).

The yield stress and tensile stress are assumed to be proportional to the allowable stress (approximate only). Actual yield stress and tensile stress temperature data should be used if it is available. The weld factor is only relevant for temperatures in the creep range. The weld factor W = 1 for temperatures below the creep onset temperature, or for seamless pipe.

Use the data plot option to plot the allowable stress versus temperature for the selected material. Use the Data Table option to display the data table in the popup window. Use the Result Table option to display a table of allowable stress versus material type. The calculations use US standard units. Change input and output units on the setup page. Refer to the help pages for notes on the data tables (click the resources button on the data bar). Use the workbook ASME B31.1 data tables to look up allowable stress data.

Reference : ANSI/ASME B31.1 : Power Piping (2014)

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CALCULATOR MODULE : ASME B31.1 Power Piping Wall Thickness   ±

Calculate ASME B31.1 power piping wall thickness from the design temperature.

Wall thickness can be calculated from either the outside diameter (constant OD), or the inside diameter (constant ID).

The allowable stress (SE) is calculated from tables A-1 to A-9. For temperatures above the data range, select either constant value, constant slope, or zero value (engineering judgement is required). The weld factor W is relevant for temperatures in the creep range. For temperatures below the creep onset temperature W = 1. The ASME Y factor can either be calculated, or user defined. For thick wall pipe (D/tm < 6) Y is calculated from the diameter. For thin wall pipe Y is calculated from the temperature. For combined internal and external pressure use the pressure difference in the calculations.

Use the data plot option to plot the allowable stress versus temperature for the selected material. Use the Data Table option to display the data table in the popup window. Use the Result Table option to display a table of wall thickness and allowable pressure versus material type (for the calculate wall thickness option the allowable pressure equals the design pressure. for the specified wall thickness option the wall thickness is constant). The calculations use SI standard units. Change input and output units on the setup page. Refer to the help pages for notes on the data tables (click the resources button on the data bar). Use the workbook ASME B31.1 data tables to look up allowable stress data.

Reference : ANSI/ASME B31.1 : Power Piping (2014)

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CALCULATOR MODULE : ASME B31.1 Power Piping Hoop Stress   ±

Calculate ASME B31.1 power piping hoop stress for metal and plastic piping.

Hoop stress can be calculated for either the minimum wall thickness (nominal wall thickness minus fabrication allowance), or the pressure design wall thickness (minimum wall thickness minus the corrosion allowance). The minimum wall thickness can be used for new pipe, or pipe in good condition. The pressure design wall thickness should be used for corroded pipe. The pipe diameter can be defined from either the outside diameter, or the inside diameter. For combined internal and external pressure use the pressure difference in the calculations. Use the workbook ASME B31.1 data tables to look up allowable stress data.

Reference : ANSI/ASME B31.1 : Power Piping (2014)

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CALCULATOR MODULE : ASME B31.1 Power Piping Hydrotest Pressure   ±

Calculate ASME B31.1 power piping hydrotest pressure and pneumatic leak test pressure for steel pipe and plastic piping.

The test pressure should be ≥ 1.5 times the design pressure for hydrotest, and ≥ 1.2 times the design pressure for pneumatic tests. The hoop stress during testing should be ≤ 90% of the yield stress. Hoop stress can be calculated for either the minimum wall thickness (nominal wall thickness minus fabrication allowance), or the pressure design wall thickness (minimum wall thickness minus the corrosion allowance).

For piping systems with combined internal and external pressure the test pressure should be calculated from the internal pressure. The hoop stress is calculated from the pressure difference during testing. Use the workbook ASME B31.1 data tables to look up allowable stress data.

Reference : ANSI/ASME B31.1 : Power Piping (2014)

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CALCULATOR MODULE : ASME B31.1 Power Piping Plastic Components   ±
CALCULATOR MODULE : ASME B31.1 Power Piping Elastic Modulus   ±

Calculate ASME B31.1 power piping elastic modulus versus temperature from table C-2. For temperatures above or below the data range, the elastic modulus is calculated with constant slope from the end data points.

Use the data plot option to plot the elastic modulus versus temperature for the selected material. Use the Data Table option to display the data table in the popup window. The calculations use SI standard units. Change input and output units on the setup page. Use the workbook ASME B31.1 data tables to look up elastic modulus data.

Reference : ANSI/ASME B31.1 : Power Piping (2014)

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CALCULATOR MODULE : ASME B31.1 Power Piping Thermal Expansion   ±

Calculate ASME B31.1 power piping thermal expansion from temperature (ASME B31.1 Table C-2).

Table C-2 provides thermal expansion strain data (mm/m) from 20 degrees C base temperature. The expansion data is used to calculate

  • thermal expansion strain from 20 degrees C to the design temperature
  • thermal expansion strain from the design base temperature to the design temperature
  • thermal expansion length from the design base temperature to the design temperature
  • thermal expansion coefficient at the design temperature
  • The average thermal expansion coefficient from the design base temperature to the design temperature

Use the data plot option to plot thermal expansion versus temperature for the selected material. Use the Data Table option to display the data table in the popup window. Use the Result Table option to display a table of expansion coefficient, expansion strain and expansion length versus material type. Strain (ε) has units meter per meter [m/m]. The expansion strain data uses units of milli meter per meter [mm/m] or [mε] milli strain. Change input and output units on the setup page. Refer to the help pages for notes on the data table (click the resources button on the data bar). Use the workbook ASME B31.1 data tables to look up expansion strain data.

Reference : ANSI/ASME B31.1 : Power Piping (2014)

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CALCULATOR MODULE : ASME B31.1 Power Piping Branch Reinforcement   ±

Calculate ASME B31.1 power piping branch reinforcement for welded and extruded branches. Refer to the figures for details (click the resources button on the data bar)

For welded branches the branch angle must be ≥ 45 degrees. The pad reinforcement area also includes any welds or saddles which are inside the reinforcement zone. The extruded branch calculation is valid for right angle branches only. Use the workbook ASME B31.1 data tables to look up allowable stress data.

Reference : ANSI/ASME B31.1 : Power Piping (2014)

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CALCULATOR MODULE : ASME B31.1 Power Piping Design Factor   ±

Calculate ASME B31.1 power piping design factors (Weld factor W, Y factor and thinning allowance B).

The Y factor is calculated from diameter for thick wall pipe (D/t < 6), or from temperature for thin wall pipe. The weld factor (W) is only relevant for design temperatures in the creep range. For design temperatures below the creep onset temperature W = 1. The weld factor does not apply for seamless pipe (W = 1). The thinning allowance (B) is an approximate estimate of the thinning on the outside radius due to bending (ASME B31.3 table 102.4.5). A power law curve has been fitted to the data values in the table. Use the workbook ASME B31.1 data tables to look up allowable stress data.

Reference : ANSI/ASME B31.1 : Power Piping (2014)

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CALCULATOR MODULE : ASME B31.1 Power Piping Blank Flange   ±
CALCULATOR MODULE : ASME B31.1 Power Piping Bend   ±
CALCULATOR MODULE : ASME B31.1 Power Piping Allowable Bolt Load And Bolt Stress   ±

Calculate ASME B31.1 power piping allowable bolt load and bolt stress from temperature (US units).

Allowable bolt stress is calculated from tables A-10. Bolt tensile area can be calculated for either ANSI threads, or ISO threads.

Use the data plot option to plot the allowable stress versus temperature for the selected material. Use the Data Table option to display the data table in the popup window (ASME B31.1 Table A-10). Use the Result Table option to display a table of allowable stress and allowable load versus material type. Use the workbook ASME B31.1 data tables to look up allowable bolt stress data.

Reference : ANSI/ASME B31.1 : Power Piping (2014)

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CALCULATOR MODULE : ASME B31.1 Power Piping Design Pressure   ±

Calculate ASME B31.1 power piping design pressure from the design temperature.

The design stress (SE) is calculated from tables A-1 to A-9. For temperatures above the data range, select either constant value, constant slope, or zero value (engineering judgement is required). The weld factor W is relevant for temperatures in the creep range. For temperatures below the creep onset temperature W = 1. The ASME Y factor can either be calculated, or user defined. For thick wall pipe (D/tm < 6) Y is calculated from the diameter. For thin wall pipe Y is calculated from the temperature. For combined internal and external pressure use the pressure difference in the calculations.

Use the table data option for a table of allowable pressure versus wall thickness for the selected pipe schedule and diameter. Use the data plot option to plot the allowable stress versus temperature for the selected material. Use the Data Table option to display the data table in the popup window. Use the Result Table option to display a table of allowable pressure versus material type, or allowable pressure versus wall thickness. The calculations use SI standard units. Change input and output units on the setup page. Refer to the help pages for notes on the data tables (click the resources button on the data bar). Use the workbook ASME B31.1 data tables to look up allowable stress data.

Reference : ANSI/ASME B31.1 : Power Piping (2014)

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CALCULATOR MODULE : ASME B31.1 Power Piping Steam Table   ±

Calculate ASME B31.1 power piping steam properties.

Steam table properties can be calculated for saturated liquid, saturated vapour, and mixed saturated liquid and vapour from quality factor. The enthalpy and internal energy are calculated from the mass. The saturation point can be calculated from either the saturation temperature, or the saturation pressure.

Note : There is an anomaly in the steam calculation for region 3 between the saturated vapour line, the regions 2/3 boundary, and the critical pressure. Refer to the region 3 anomaly help page for more details (click the utility button on the data bar). IAPWS R7-97 is intended for industrial use, and is a simplified version of IAPWS R6-95 for scientific use.

Reference : ANSI/ASME B31.1 : Power Piping (2014)

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CALCULATOR MODULE : ASME B31.1 Power Piping Mass And Weight   ±

Calculate ASME B31.1 power piping unit mass (mass per length), unit weight (weight per length), and total mass for metal and plastic pipe.

The mass per joint can be calculated from the joint length. Construction quantities can be calculated from the total pipe length. Pipe unit mass (mass per length) and unit weight (weight per length) can be calculated for multi layer pipelines (dry empty, dry full, wet empty and wet full piping). For multi layer pipelines, the first internal layer is the line pipe. Change the number of layers on the setup page.

Plastic pipe wall thickness can be defined by wall thickness or diameter ratio (DR or IDR). Select standard diameter ratios from the plastic pipe schedule (SDR or SIDR), or use user defined diameter ratios (DR or IDR). Plastic pipe is generally only used in low pressure auxilliary systems.

Use the Result Table option to display a table of pipe mass or pipe weight versus wall thickness for the selected diameter.

Reference : ANSI/ASME B31.1 : Power Piping (2014)

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CALCULATOR MODULE : ASME B31.1 Power Piping Steam Pressure Relief   ±

Calculate ASME B31.1 power piping steam mass flow rate for pressure relief valves, headers and vents.

For pressure relief valves the mass flow rate can be calculated for isentropic or isothermal flow. The pressure relief valve is assumed to exit directly to ambient pressure. If the ambient pressure is less than the critical pressure the flow is critical (Mc = 1 for isentropic flow and Mc = √(1/γ) for isothermal flow). If exit pressure is greater than the critical nozzle pressure, the flow is sub critical (M < Mc). For isothermal flow a suitable isothermal temperature should be determined. The valve nozzle orifice diameter and cross section area can be calculated from API letter designation (API 526 type D to T), or user defined.

For a combined pressure relief valve and pressure relief header, the mass flow rate can be calculated for

  • Isentropic nozzle and adiabatic header
  • Isentropic nozzle and isothermal header
  • Isothermal nozzle and isothermal header

The pressure relief valve is assumed to exit directly into the header. If the header inlet pressure is less than or equal to the nozzle critical pressure the nozzle flow is critical, and the mass flow rate is restricted by the nozzle. The header inlet pressure is calculated so that the header mass flow rate equals the nozzle mass flow rate. If the header inlet pressure is greater than the critical nozzle pressure, the nozzle flow is sub critical (M < Mc), and the mass flow rate is restricted by the header. The mass flow rate is calculated so that the header inlet pressure is equal to the nozzle pressure. The mass flow rate through the nozzle is always equal to the mass flow rate through the header.

Pressure relief headers are normally part of a pressure relief system, and are usually attached to an upstream device such as a pressure relief valve, a pressure relief vent, or another pressure relief header. The inlet pressure of the header is less than or equal to exit pressure from the upstream device. The header should be sized so that the calculated header mass flowrate is greater than or equal to the mass flowrate of the upstream device. For headers attached to multiple upstream devices, the header mass flowrate is divided by the number of devices. If the header is oversized, the header inlet pressure will reduce so that the actual header mass flowrate is equal to the upstream mass flowrate (there is a pressure drop between the upstream exit and the header inlet).

Pressure relief vents are constant diameter piping, usually with either a valve or a burst disk. Vents usually exit either to atmosphere, or into a header. If the ambient pressure is less than the critical exit pressure exit flow is critical. If the ambient pressure is greater than the critical exit pressure, exit flow is sub critical (M < Mc). The header or vent inlet flow is assumed to be sub critical for all flow conditions. Header and vent pressure losses are calculated from the pressure loss factor (fld = fL/D + K). The Darcy friction factor f is calculated for fully turbulent flow using the rough pipe equation. Minor losses can be included by the minor loss K factor, and should include valves and bends etc. The discharge coefficient can also be used for minor losses, and as a safety factor.

Reference : ANSI/ASME B31.1 : Power Piping (2014)

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CALCULATOR MODULE : ASME B31.1 Power Piping Steam Mass And Flow Rate   ±

Calculate ASME B31.1 power piping steam mass, velocity and flow rate from the steam table (IAPWS R7-97 Steam Table).

Steam mass and volume can be calculated from steam temperature and pressure, and either steam mass, steam volume, or piping length. Steam flow rate and velocity can be calculated from steam temperature and pressure, and either steam mass flow rate, steam volume flow rate, or steam velocity.

Steam properties can be calculated for water and steam, saturated water, saturated steam, saturated water and steam, metastable water, and metastable steam. The calculations for water and steam are valid between 273.15 K and 1073.15 K (0 to 100 MPa), and between 1073.15 K and 2273.15 K (0 to 50 MPa).

The saturated water and steam calculations are valid between 273.15 K and 647.096 K.

The metastable calculation is valid between 273.15 K and 647.096 K, and for pressure from the saturated vapour line to the 5% equilibium moisture line (user defined).

Note : There is an anomaly in the steam calculation for region 3 between the saturated vapour line, the regions 2/3 boundary, and the critical pressure. Refer to the region 3 anomaly help page for more details (click the utility button on the data bar).

Reference : ANSI/ASME B31.1 : Power Piping (2014)

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CALCULATOR MODULE : Compressible Flow Pressure Relief Valve   ±

Calculate compressible flow pressure relief valve capacity for isentropic, isothermal, and adiabatic conditions.

For pressure relief valves with no header, the mass flow rate can be calculated for isentropic or isothermal flow. The pressure relief valve is assumed to exit directly to ambient pressure. If the ambient pressure is less than the critical pressure the flow is critical (Mc = 1 for isentropic flow and Mc = √(1/γ) for isothermal flow). If the ambient pressure is greater than the critical nozzle pressure, the flow is sub critical (M < Mc). For isothermal flow the stagnation temperature should be close to or equal to the ambient temperature (for example a gas transmission pipeline). Phase changes are ignored.

For a combined pressure relief valve and pressure relief header, the mass flow rate can be calculated for

  • Isentropic nozzle and adiabatic header
  • Isentropic nozzle and isothermal header
  • Isothermal nozzle and isothermal header

The pressure relief valve is assumed to exit directly into the header. If the header inlet pressure is less than or equal to the nozzle critical pressure the nozzle flow is critical (Mc = 1 for isentropic flow and Mc = √(1/γ) for isothermal flow), and the mass flow rate is restricted by the nozzle. The header inlet pressure is calculated so that the header mass flow rate equals the nozzle mass flow rate. If the header inlet pressure is greater than the critical nozzle pressure, the nozzle flow is sub critical (M < Mc), and the mass flow rate is restricted by the header. The mass flow rate is calculated so that the header inlet pressure is equal to the nozzle pressure. The mass flow rate through the nozzle is always equal to the mass flow rate through the header.

For a pressure relief header, the mass flow rate can be calculated for adiabatic or isothermal flow. If the header is attached directly to the outlet of a pressure relief valve (PRV), the header inlet pressure should be set equal to the PRV nozzle outlet pressure. The header should be sized so that the calculated header mass flowrate is greater than or equal to the PRV mass flowrate. For headers with more than one PRV, the header mass flowrate is divided by the number of PRV's. If the header is oversized, the header inlet pressure will reduce so that the actual header mass flowrate is equal to the nozzle mass flowrate (there is a pressure drop between the PRV outlet and the header inlet).

Note : If the PRV is attached to a small diameter header which feeds into a larger diameter header (possibly with multiple PRVs), the large diameter header should be sized first. The inlet pressure for the large diameter header is used as the ambient pressure for the smaller diameter header (and PRV).

Header pressure losses are calculated from the pressure loss factor (fld = fL/D + K). The Darcy friction factor f is calculated for fully turbulent flow using the rough pipe equation. The header is assumed to be constant diameter. Minor losses can be included by the minor loss K factor, and should include valves and bends etc. The header entry and exit losses should not be included (the fluid dynamic pressure loss is included in the calculation). The discharge coefficient can also be used for minor losses, and as a safety factor. If the ambient pressure is less than the critical header pressure the header exit flow is critical (Mc = 1 for isentropic flow and Mc = √(1/γ) for isothermal flow). If the ambient pressure is greater than the critical header pressure, the header exit flow is sub critical (M < Mc). The header entry flow is assumed to be sub critical for all flow conditions.

The effective PRV valve nozzle orifice diameter and cross section area can be calculated from API letter designation (API 526 type D to T). API effective orifice sizing is used to compensate for the friction pressure losses in the relief valve. The combination of valve and nozzle orifice must be tested with the operating fluid at the design conditions, and certified as having a flow rate greater than or equal to the calculated flow rate for the equivalent size. The API 526 orifice sizing assumes isentropic flow. For certified API 526 valves, the isentropic nozzle calculation option should be used.

Note : The pressure relief header calculation is not suitable for pressure relief vents. Headers are assumed to be part of a PRV system. Vents are constant diameter piping attached to a pipeline or pressure vessel.

Use the Result Plot option to plot pressure, mach number and mass flow rate.

Reference : Fluid Mechanics, Frank M White, McGraw Hill

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CALCULATOR MODULE : Compressible Flow Gas Property   ±

Calculate compressible flow gas properties.

Calculate gas specific heat constant pressure, specific heat constant volume, specific heat ratio, molar mass, gas constant, gas specific gravity, gas compressibility factor and density from gas temperature and pressure. The gas compressibility factor is calculated from the critical point temperature, critical point temperature, and the accentric factor using either the Peng Robinson, Soave, Redlich Kwong or Van Der Waals equation of state (EOS).

Reference : Fluid Mechanics, Frank M White, McGraw Hill

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CALCULATOR MODULE : Compressible Flow Pressure Relief Vent   ±

Calculate compressible flow pressure relief vent flow rate and pressure drop for either adiabatic or isothermal flow.

The vent is modelled as a frictionless entry, combined with a frictional constant diameter duct. For adiabatic flow the vent entry is assumed to be isentropic. For isothermal flow, the vent entry is assumed to be isothermal. The vent entry is assumed to be subsonic at all conditions. The pipeline is assumed to be at stagnation conditions (M = 0). At high pressure the vent exit flow is critical flow (Mc = 1 for adiabatic low and `Mc = 1 / (√γ)` for isothermal flow : γ = the gas specific heat ratio). At lower pressures the vent exit flow is sub critical (M < Mc).

Vent flow rate is calculated from the vent pressure loss factor (fld).

`fld = fd L/D + K `

where :

fld = vent pressure loss factor
fd = Darcy friction factor
L = vent length
D = vent inside diameter
K = minor loss K factor

The Darcy friction factor is calculated assuming fully turbulent flow. Minor losses should include the vent entry, and valves, bends etc.. The vent exit should not be included (the fluid dynamic pressure is included in the calculation). The discharge coefficient can be used as a safety factor.

Note : The vent calculation is not suitable for pressure relief headers which are part of a pressure relief valve (PRV) system.

Use the Result Plot option to plot inlet and exit pressure versus stagnation pressure, inlet and exit mach number versus stagnation pressure, or mass flow rate versus stagnation pressure and flow type.

Reference : Fluid Mechanics, Frank M White, McGraw Hill

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CALCULATOR MODULE : API 520 Steam Pressure Relief Valve   ±

Calculate API 520 steam pressure relief valve (PRV) and rupture disk size.

The flow through the relief valve nozzle is analysed using the Napier equation. For temperatures above 1200 F (922 K), the gas PRV calculation should be used. If the back pressure is greater than the critical (sonic) pressure the flow is sub sonic (M < 1).

Friction losses are accounted for using the discharge coefficient Kd. For initial sizing of PRV's the effective nozzle diameter should be used with the discharge coefficient Kd = 0.975. The actual nozzle diameter and rated coefficient of discharge should be used to verify that the selected PRV is suitable for the required flow rate. The PRV effective diameter is taken from API 526 (letter designation D to T). Changes in phase are not accounted for.

The calculation can also be used for rupture disks. The rupture disk diameter should be substituted for the nozzle diameter, with a discharge coefficient Kd = 0.62. Rupture disks can also be analysed as part of a relief vent system using the flow resistance method.

Note : The ideal gas calculators use the ideal gas compressible flow equations. The API 520 gas and steam calculations use an approximation of the ideal gas compressible flow equations. Use the ideal gas calculators for a comparison with the API 520 calculators.

Reference : API 520 Sizing, Selection And Installation Of Pressure Relieving Devices (2014)

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CALCULATOR MODULE : API 520 Correction Factor   ±
CALCULATOR MODULE : API 520 Darcy Friction Factor   ±

Calculate API 520 Darcy friction factor and pressure loss factor for single phase liquid and single phase gas.

The Darcy friction factor can be caclulated from either the Moody diagram or the Von Karman rough pipe equation (API 520 Annex E).

At high Reynolds numbers the Moody diagram friction factor is fully turbulent and is dependent on the pipe roughness only. The pressure loss factor (fLe/ID) includes minor losses. Minor losses can be entered as either a K factor, an equivalent added length, or an equivalent added length over diameter ratio.

Reference : API 520 Sizing, Selection And Installation Of Pressure Relieving Devices (2014)

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CALCULATOR MODULE : API 520 Pressure Relief Vent   ±

Calculate API 520 flow rate through a constant diameter pressure relief vent.

The vent entry is assumed to be a pressure vessel or piping at stagnation pressure (valid when the pipe or vessel diameter is much greater than the vent diameter). The calculated vent exit pressure is flowing pressure (stagnation pressure minus dynamic pressure).

Vent pressure losses are calculated from the vent pressure loss factor (fld = fL/D + K). Minor losses should include the vent entry, valves and bends etc. The vent exit should not be included. The discharge coefficient can be used to factor the flow rate, depending on the design requirements.

For rupture disks, the flow resistance factor of the rupture Kr should be included in the minor losses (the resistance factor should be factored for the vent diameter). A discharge coefficient of 0.9 or less should be used for rupture disks. Alternatively, the PRV calculators can be used for rupture disk calculations.

Note : The ideal gas calculators use the ideal gas compressible flow equations. The API 520 gas and steam calculations use an approximation of the ideal gas compressible flow equations. Use the ideal gas calculators for a comparison with the API 520 calculators.

Reference : API 520 Sizing, Selection And Installation Of Pressure Relieving Devices (2014)

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CALCULATOR MODULE : API 520 Back Pressure   ±

Calculate API 520 back pressure from mass flow rate through a constant diameter vent.

The calculated vent entry and exit pressures are flowing pressure (stagnation pressure minus dynamic pressure). Minor losses should include bends and valves etc. The vent entry and exit should not be included in the minor losses. The discharge coefficient can be used to factor the mass flow rate, depending on design requirements.

Where multiple pressure relieving devices share a common vent, the back pressure should be calculated for the total mass flow rate.

For relief vents with sections of increasing diameter, the back pressure should be calculated for each constant diameter section, going backwards from exit. The (flowing) exit pressure for each section equals the (flowing) inlet pressure for the previous section.

For pressure relief valves or rupture disks, the (flowing) inlet pressure for the vent is used as the (flowing) back pressure for the pressure relief device. This is valid provided that the vent diameter is greater than the diamter of the PRV nozzle or rupture disk.

Note : The ideal gas calculators use the ideal gas compressible flow equations. The API 520 gas and steam calculations use an approximation of the ideal gas compressible flow equations. Use the ideal gas calculators for a comparison with the API 520 calculators.

Reference : API 520 Sizing, Selection And Installation Of Pressure Relieving Devices (2014)

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CALCULATOR MODULE : Water And Steam Viscosity   ±

Calculate dynamic and kinematic viscosity of water and steam from temperature and pressure.

The viscosity is calculated from temperature and density using the IAPWS R12-08 industrial equation (u2 = 1). The density can be calculated from temperature and pressure using IAPWS R7-97.

Note : There is an anomaly in the calculated viscosity and density close to the critical point. Refer to the help pages for more details (click the utility button on the data bar).

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CALCULATOR MODULE : Water And Steam Density   ±
CALCULATOR MODULE : Water And Steam Heat Capacity   ±

Calculate water and steam heat capacity from temperature and pressure (IAPWS R7-97).

Heat capacity and thermodynamic properties can be calculated for water and steam, saturated water, saturated steam, saturated water and steam, metastable water, and metastable steam. The calculations for water and steam are valid between 273.15 K and 1073.15 K (0 to 100 MPa), and between 1073.15 K and 2273.15 K (0 to 50 MPa).

The saturated water and steam calculations are valid between 273.15 K and 647.096 K.

Note : There is an anomaly in the steam calculation for region 3 between the saturated vapour line, the region 2/3 boundary, and the critical pressure. Refer to the region 3 anomaly help page for more details (click the utility button on the data bar). IAPWS R7-97 is intended for industrial use, and is a simplified version of IAPWS R6-95 for scientific use. IAPWS R7-97 was developed as an improvement of the IFC-67 model.

Reference : IAPWS R7-97 Industrial Formulation for thermodynamic Properties of Water and Steam

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CALCULATOR MODULE : IAPWS R7-97 Steam Table   ±

Calculate IAPWS R7-97 steam tables from temperature and pressure.

Steam table properties can be calculated for water and steam, saturated water, saturated steam, saturated water and steam, metastable water, and metastable steam.

Note : There is an anomaly in the steam calculation for region 3 between the saturated vapour line, the region 2/3 boundary, and the critical pressure. Refer to the region 3 anomaly help page for more details (click the utility button on the data bar). IAPWS R7-97 is intended for industrial use, and is a simplified version of IAPWS R6-95 for scientific use. IAPWS R7-97 was developed as an improvement of the IFC-67 model.

Reference : IAPWS R7-97 Industrial Formulation for thermodynamic Properties of Water and Steam

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CALCULATOR MODULE : IAPWS R7-97 Steam Vapour Pressure   ±

Calculate IAPWS R7-97 saturated vapour pressure and temperature.

The saturation point can be calculated from either the saturation temperature, or the saturation pressure.

Steam properties can be calculated for saturated liquid, saturated vapour, and mixed saturated liquid and vapour from quality factor. The enthalpy and internal energy are calculated from the mass. Use the Result Plot option to plot the steam pressure and steam properties versus temperature.

Note : There is an anomaly in the steam calculation for region 3 between the saturated vapour line, the region 2/3 boundary, and the critical pressure. Refer to the region 3 anomaly help page for more details (click the utility button on the data bar). IAPWS R7-97 is intended for industrial use, and is a simplified version of IAPWS R6-95 for scientific use. IAPWS R7-97 was developed as an improvement of the IFC-67 model.

Reference : IAPWS R7-97 Industrial Formulation for thermodynamic Properties of Water and Steam

Change Module :

CALCULATOR MODULE : IAPWS R7-97 Steam Volume And Mass   ±

Calculate IAPWS R7-97 steam table properties, and steam energy from temperature, pressure and mass.

Steam table properties can be calculated for water and steam, saturated water, saturated steam, saturated water and steam, metastable water, and metastable steam. The enthalpy and internal energy are calculated from the mass. Use the Result Plot option to plot the steam properties versus temperature and pressure.

Note : There is an anomaly in the steam calculation for region 3 between the saturated vapour line, the region 2/3 boundary, and the critical pressure. Refer to the region 3 anomaly help page for more details (click the utility button on the data bar). IAPWS R7-97 is intended for industrial use, and is a simplified version of IAPWS R6-95 for scientific use. IAPWS R7-97 was developed as an improvement of the IFC-67 model.

Reference : IAPWS R7-97 Industrial Formulation for thermodynamic Properties of Water and Steam

Change Module :

CALCULATOR MODULE : IAPWS R7-97 Steam Volume And Mass Flow Rate   ±

Calculate IAPWS R7-97 steam table properties, and steam power from temperature, pressure and mass flow rate.

Steam table properties can be calculated for water and steam, saturated water, saturated steam, saturated water and steam, metastable water, and metastable steam. The enthalpy rate and internal energy rate (or power) are calculated from the mass flow rate.

Note : There is an anomaly in the steam calculation for region 3 between the saturated vapour line, the region 2/3 boundary, and the critical pressure. Refer to the region 3 anomaly help page for more details (click the utility button on the data bar). IAPWS R7-97 is intended for industrial use, and is a simplified version of IAPWS R6-95 for scientific use. IAPWS R7-97 was developed as an improvement of the IFC-67 model.

Reference : IAPWS R7-97 Industrial Formulation for thermodynamic Properties of Water and Steam

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CALCULATOR MODULE : IAPWS R7-97 Steam Boiler Power   ±

Calculate IAPWS R7-97 steam boiler power from temperature, pressure and mass flow rate.

The boiler power is calculated from the change of enthalpy between the inlet water, and the outlet steam. The boiler power can be calculated for either dry steam (boiler plus super heater), or saturated steam (boiler only). For dry steam the boiler power includes the combined power of the boiler and super heater. The boiler pressure is assumed constant. The enthalpy change is positive.

Note : There is an anomaly in the steam calculation for region 3 between the saturated vapour line, the region 2/3 boundary, and the critical pressure. Refer to the region 3 anomaly help page for more details (click the utility button on the data bar). IAPWS R7-97 is intended for industrial use, and is a simplified version of IAPWS R6-95 for scientific use. IAPWS R7-97 was developed as an improvement of the IFC-67 model.

Reference : IAPWS R7-97 Industrial Formulation for thermodynamic Properties of Water and Steam

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CALCULATOR MODULE : IAPWS R7-97 Steam Condenser Power   ±

Calculate IAPWS R7-97 steam condenser power from temperature, pressure and mass flow rate.

The condenser power is calculated from the change of enthalpy between the inlet steam, and the outlet water. The enthalpy change is negative for a condenser. The condenser pressure is assumed constant.

Note : There is an anomaly in the steam calculation for region 3 between the saturated vapour line, the region 2/3 boundary, and the critical pressure. Refer to the region 3 anomaly help page for more details (click the utility button on the data bar). IAPWS R7-97 is intended for industrial use, and is a simplified version of IAPWS R6-95 for scientific use. IAPWS R7-97 was developed as an improvement of the IFC-67 model.

Reference : IAPWS R7-97 Industrial Formulation for thermodynamic Properties of Water and Steam

Change Module :

CALCULATOR MODULE : IAPWS R7-97 Steam Turbine Power   ±

Calculate IAPWS R7-97 steam turbine or steam engine power from temperature, pressure and mass flow rate.

The turbine power is calculated from the change of enthalpy between the inlet and outlet conditions. The enthalpy change is negative for a turbine (postive work). Heat losses from the turbine, phase changes, fluid velocity and elevation are ignored. Check the phase of the inlet and outlet fluid.

The maximum work power corresponds to an isentropic process with delta specific entropy = 0 (isentropic efficiency = 100%). Check that the delta specific entropy is ≥ 0. Negative changes in specific entropy are not thermodynamically valid. The turbine efficiency factor E accounts for the mechanical efficiency of the turbine only. It does not include the isentropic efficiency.

Note : There is an anomaly in the steam calculation for region 3 between the saturated vapour line, the region 2/3 boundary, and the critical pressure. Refer to the region 3 anomaly help page for more details (click the utility button on the data bar). IAPWS R7-97 is intended for industrial use, and is a simplified version of IAPWS R6-95 for scientific use. IAPWS R7-97 was developed as an improvement of the IFC-67 model.

Reference : IAPWS R7-97 Industrial Formulation for thermodynamic Properties of Water and Steam

Change Module :

CALCULATOR MODULE : IAPWS R7-97 Steam Work Or Heat Power   ±

Calculate IAPWS R7-97 steam work or heat power for a general system from temperature, pressure and mass flow rate.

The heat or work power is calculated from the change of enthalpy between the inlet and outlet fluids. Check the phase of the inlet and outlet fluid. The enthalpy change is positive if heat or work is added to the system, and negative if heat or work are removed from the system.

Note : There is an anomaly in the steam calculation for region 3 between the saturated vapour line, the region 2/3 boundary, and the critical pressure. Refer to the region 3 anomaly help page for more details (click the utility button on the data bar). IAPWS R7-97 is intended for industrial use, and is a simplified version of IAPWS R6-95 for scientific use. IAPWS R7-97 was developed as an improvement of the IFC-67 model.

Reference : IAPWS R7-97 Industrial Formulation for thermodynamic Properties of Water and Steam

Change Module :

CALCULATOR MODULE : IAPWS R7-97 Steam Boiler Feed Pump Power   ±

Calculate IAPWS R7-97 boiler feed pump power from pressure and mass flow rate.

Changes of elevation and velocity are ignored.

Note : There is an anomaly in the steam calculation for region 3 between the saturated vapour line, the region 2/3 boundary, and the critical pressure. Refer to the region 3 anomaly help page for more details (click the utility button on the data bar). IAPWS R7-97 is intended for industrial use, and is a simplified version of IAPWS R6-95 for scientific use. IAPWS R7-97 was developed as an improvement of the IFC-67 model.

Reference : IAPWS R7-97 Industrial Formulation for thermodynamic Properties of Water and Steam

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CALCULATOR MODULE : IAPWS R7-97 Steam Quality   ±

Calculate IAPWS R7-97 wet saturated steam quality from throttling calorimeter outlet temperature.

The steam expansion through the calorimeter is assumed to be adiabatic. The outlet pressure is normally atmospheric. The calculation is only valid for dry steam at the outlet of the calorimeter. Wet steam will give an incorrect result.

Note : There is an anomaly in the steam calculation for region 3 between the saturated vapour line, the region 2/3 boundary, and the critical pressure. Refer to the region 3 anomaly help page for more details (click the utility button on the data bar). IAPWS R7-97 is intended for industrial use, and is a simplified version of IAPWS R6-95 for scientific use. IAPWS R7-97 was developed as an improvement of the IFC-67 model.

Reference : IAPWS R7-97 Industrial Formulation for thermodynamic Properties of Water and Steam

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CALCULATOR MODULE : IAPWS R7-97 Steam Adiabatic Constant Enthalpy   ±

Calculate IAPWS R7-97 constant enthalpy adiabatic steam temperature from initial enthalpy and final pressure.

For an adiabatic process the enthalpy is constant. Initial enthalpy can be calculated from the steam table or user defined. The anomaly zone is set to region 2 (region 3 does not converge properly).

Note : The steam is assumed to be stationary at the initial and final conditions. For moving steam use the constant entropy calculator for constant stagnation enthalpy (ho = h + 1/2 V^2).

Use the Result Plot option to plot final (adiabatic) properties versus initial enthalpy.

Note : There is an anomaly in the steam calculation for region 3 between the saturated vapour line, the region 2/3 boundary, and the critical pressure. Refer to the region 3 anomaly help page for more details (click the utility button on the data bar). IAPWS R7-97 is intended for industrial use, and is a simplified version of IAPWS R6-95 for scientific use. IAPWS R7-97 was developed as an improvement of the IFC-67 model.

Reference : IAPWS R7-97 Industrial Formulation for thermodynamic Properties of Water and Steam

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CALCULATOR MODULE : IAPWS R7-97 Steam Isentropic Constant Entropy   ±

Calculate IAPWS R7-97 constant entropy isentropic steam temperature from initial entropy and final pressure.

For an isentropic process the entropy is constant. Initial entropy can be calculated from the steam table or user defined. The anomaly zone is set to region 2 (region 3 does not converge properly).

Note : For an isentropic process the stagnation enthalpy is constant (ho = h + 1/2 V^2). The stagnation enthalpy can be used to calculate the steam velocity.

Use the Result Plot option to plot final (isentropic) steam properties versus initial entropy.

Note : There is an anomaly in the steam calculation for region 3 between the saturated vapour line, the region 2/3 boundary, and the critical pressure. Refer to the region 3 anomaly help page for more details (click the utility button on the data bar). IAPWS R7-97 is intended for industrial use, and is a simplified version of IAPWS R6-95 for scientific use. IAPWS R7-97 was developed as an improvement of the IFC-67 model.

Reference : IAPWS R7-97 Industrial Formulation for thermodynamic Properties of Water and Steam

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CALCULATOR MODULE : IAPWS R7-97 Steam Isoenergetic Constant Internal Energy   ±

Calculate IAPWS R7-97 constant internal energy isoenergetic steam temperature from initial internal energu and final pressure.

For an isoenergetic process the internal energy is constant. Initial internal energy can be calculated from the steam table or user defined. The anomaly zone is set to region 2 (region 3 does not converge properly). Use the Result Plot option to plot final (isoenergetic) properties and temperature versus initial internal energy.

Note : There is an anomaly in the steam calculation for region 3 between the saturated vapour line, the region 2/3 boundary, and the critical pressure. Refer to the region 3 anomaly help page for more details (click the utility button on the data bar). IAPWS R7-97 is intended for industrial use, and is a simplified version of IAPWS R6-95 for scientific use. IAPWS R7-97 was developed as an improvement of the IFC-67 model.

Reference : IAPWS R7-97 Industrial Formulation for thermodynamic Properties of Water and Steam

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CALCULATOR MODULE : IAPWS R7-97 Steam Isentropic Efficiency   ±

Calculate IAPWS R7-97 steam isentropic efficiency from inlet and outlet temperature and pressure.

Isentropic efficiency is the ratio of the change in enthalpy of an actual process over the change in enthalpy of an isentropic constant entropy process. The maximum possible isentropic efficiency is 100%. For an isentropic process the change in entropy equals 0. The actual change in entropy must be ≥ 0. For a steam turbine the output work is ≤ the change in enthalpy. The turbine efficiency is the ratio of output work over the change in enthalpy.

The inlet temperature and pressure are assumed to be greater than the outlet temperature and pressure. The anomaly zone is set to region 2 (region 3 does not converge properly). Use the Result Plot option to plot isentropic properties and isentropic temperature versus outlet pressure.

Note : There is an anomaly in the steam calculation for region 3 between the saturated vapour line, the region 2/3 boundary, and the critical pressure. Refer to the region 3 anomaly help page for more details (click the utility button on the data bar). IAPWS R7-97 is intended for industrial use, and is a simplified version of IAPWS R6-95 for scientific use. IAPWS R7-97 was developed as an improvement of the IFC-67 model.

Reference : IAPWS R7-97 Industrial Formulation for thermodynamic Properties of Water and Steam

Change Module :

CALCULATOR MODULE : IAPWS R7-97 Steam Critical Flow   ±

Calculate IAPWS R7-97 isentropic steam critical flow properties from stagnation temperature and pressure.

Flow properties can be calculated for either critical flow, or from a user defined flowing pressure. Flow properties are valid for the vapour phase only. For critical flow the mass flux is a maximum. theoretical critical Mach number equals 1. The Mach number will vary for a user defined flowing pressure. The flowing velocity is calculated from the stagnation enthalpy (ho = h + 1/2 V^2). The anomaly zone is set to region 2 (region 3 does not converge properly). Use the Result Plot option to plot isentropic flowing properties and isentropic temperature versus either flowing pressure or Mach number.

Note : There is an anomaly in the steam calculation for region 3 between the saturated vapour line, the region 2/3 boundary, and the critical pressure. Refer to the region 3 anomaly help page for more details (click the utility button on the data bar). IAPWS R7-97 is intended for industrial use, and is a simplified version of IAPWS R6-95 for scientific use. IAPWS R7-97 was developed as an improvement of the IFC-67 model.

Reference : IAPWS R7-97 Industrial Formulation for thermodynamic Properties of Water and Steam

Change Module :

CALCULATOR MODULE : IAPWS R7-97 Steam Nozzle   ±

Calculate IAPWS R7-97 isentropic steam nozzle flow properties from stagnation temperature and pressure.

For critical flow the mass flux is a maximum (theoretical critical Mach number equals 1). The flowing velocity is calculated from the stagnation enthalpy (ho = h + 1/2 V^2). If the ambient pressure is greater than the critical nozzle pressure the flow is sub critical. Flow properties are valid for the vapour phase only. Check the nozzle density and Mach number to ensure the calculations are valid. The anomaly zone is set to region 2 (region 3 does not converge properly). Use the Result Plot option to plot isentropic nozzle properties versus stagnation temperature and pressure, and mass flow rate versus either nozzle diameter or nozzle area (the plot calculation is slow - a modern browser is recommended).

Note : There is an anomaly in the steam calculation for region 3 between the saturated vapour line, the region 2/3 boundary, and the critical pressure. Refer to the region 3 anomaly help page for more details (click the utility button on the data bar). IAPWS R7-97 is intended for industrial use, and is a simplified version of IAPWS R6-95 for scientific use. IAPWS R7-97 was developed as an improvement of the IFC-67 model.

Reference : IAPWS R7-97 Industrial Formulation for thermodynamic Properties of Water and Steam

Change Module :

CALCULATOR MODULE : ASME Steam Table   ±

Calculate ASME steam tables from temperature and pressure.

Steam Table table properties can be calculated for water and steam, saturated water, saturated steam, saturated water and steam, metastable water, and metastable steam. Use the plot and table options to generate tables and plots of steam and water properties. The saturation point can be calculated from either the saturation temperature, or the saturation pressure. Use the Result Plot option to plot steam properties versus temperature and pressure.

Note : The steam tables are caculated from IAPWS R7-97 industrial steam properties. IAPWS R7-97 was developed as an improvement of the IFC-67 model. There is an anomaly in the steam calculation for region 3 between the saturated vapour line, the regions 2/3 boundary, and the critical pressure. Refer to the region 3 anomaly help page for more details.

    Related Modules :

    CALCULATOR MODULE : IAPWS R12-08 Fresh Water Dynamic And Kinematic Viscosity   ±

    Calculate the dynamic viscosity and kinematic viscosity of water and steam using the IAPWS R12-08 industrial equation (u2 = 1).

    The viscosity can be either calculated directly from temperature and density, or from temperature and pressure using IAPWS R7-97 to calculate the density.

    Note : There is an anomaly in the calculated density and viscosity close to the critical point. Refer to the help pages for more details (click the utility button on the data bar).

    References :

    IAPWS R12-08 Industrial Formulation 2008 for the Viscosity of Ordinary Water Substance
    IAPWS R7-97 Industrial Formulation for thermodynamic Properties of Water and Steam

      Related Modules :

      DATA MODULE : Fluid Dynamic And Kinematic Viscosity ( Open In Popup Workbook )   ±
      DATA MODULE : Fluid Vapour Pressure ( Open In Popup Workbook )   ±
      DATA MODULE : Water And Steam ( Open In Popup Workbook )   ±
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