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Gas Pipeline Flow Rate Modules

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CALCULATOR MODULE : ASME B31.3 Process Piping Fluid Velocity And Flow Rate   ±

Calculate ASME B31.3 process piping fluid velocity and flow rate for two phase gas liquid piping, and three phase black oil piping (gas water and oil).

The two phase fluid calculator can be used for single phase gas, single phase liquid, or two phase gas and liquid. The three phase black oil calculator can be used for single phase oil, single phase water, two phase oil and water, and three phase oil, water and gas. Water cut is the volume fraction of water in the liquid phase (ignoring the gas phase). Gas oil ratio (GOR) is the ratio of gas moles to liquid volume (ignoring the water phase). Gas moles are commonly measured as gas volume at standard conditions, eg SCM (Standard Conditions Meter) or SCF (Standard Conditions Feet).

Reference : ANSI/ASME B31.3 : Process Piping (2018)

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CALCULATOR MODULE : ASME B31.8 Gas Pipeline Fluid Velocity And Flow Rate   ±

Calculate ASME ASME B31.8 gas pipeline fluid velocity and flow rate for two phase gas liquid piping, and three phase black oil piping (gas water and oil).

The two phase fluid calculator can be used for single phase gas, single phase liquid, or two phase gas and liquid. The three phase black oil calculator can be used for single phase oil, single phase water, two phase oil and water, and three phase oil, water and gas. Water cut is the volume fraction of water in the liquid phase (ignoring the gas phase). Gas oil ratio (GOR) is the ratio of gas moles to liquid volume (ignoring the water phase). Gas moles are commonly measured as gas volume at standard conditions, eg SCM (Standard Conditions Meter) or SCF (Standard Conditions Feet).

Reference : ANSI/ASME B31.8 : Gas Transmission And Distribution Piping Systems (2018)

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CALCULATOR MODULE : Piping Fitting Minor Loss Factor   ±

Calculate pipe fitting minor loss factors.

Minor loss factors can be defined as:

  • Av (SI) flow coefficient - the flow in cubic meters per second fluid density 1 kilogram per cubic meter which gives a pressure drop of 1 Pa
  • Cv-uk (UK) flow coefficient - the flow in UK gallons per minute of water at 60 degrees F which gives a pressure drop of 1 psi
  • Cv-us (US) flow coefficient - the flow in US gallons per minute of water at 60 degrees F which gives a pressure drop of 1 psi
  • Cv-met (Metric) flow coefficient - the flow in liters per minute of water at 16 degrees C which gives a pressure drop of 1 bar
  • Kv (EU) flow coefficient - the flow in cubic meters per hour of water at 16 degrees C which gives a pressure drop of 1 bar
  • Cv* the dimensionless US flow factor = Cv-us / din^2 (din is the inside diameter in inches)
  • K factor - the ratio of pressure loss over the dynamic pressure
  • Cd or discharge coefficient - the ratio of the actual flow rate of the fluid through the fitting over the frictionless flow rate.

The K factor and discharge coefficient are dimensionless and can be used with any consistent set of units. The dimensionless flow coefficient has inconsistent units, and is unit specific. The flow coefficient Av, Cv-us, Cv-uk, Cv-met and Kv have dimensions length squared, and can not be used interchangeably between different systems of units.

Note : The friction factor K, discharge coefficient Cd, dimensionless flow coefficient Cv*, and flow coefficients Av, Cv-uk, Cv-us, Cv-met and Kv are used in different situations. The discharge coefficient is usually used for discharge through an orifice, but can also be used in other situations (for example pressure relief valves). The flow coefficients Av, Cv-uk, Cv-us, Cv-met and Kv, and the dimensionless flow coefficient Cv* are usually used for valves, but can also be used for other fittings. Engineering judgement is required to determine the correct minor loss factor to use.

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CALCULATOR MODULE : Piping Fitting Pressure Loss   ±

Calculate outlet pressure and pressure loss through piping and fittings.

The pressure loss is calculated from the Moody diagram using the Darcy-Weisbach friction factor. The Darcy friction factor can be calculated using either the Hagen-Poiseuille laminar flow equation, the original Colebrook White turbulent flow equation, or the modified Colebrook White equation. Changes in elevation are ignored.

For liquid piping with fittings the outlet pressure is calculated by:

`Po = P - 8 (fL/D+ΣK) ρ (Q^2) / (pi^2D^4) `
`ΔP = P - Po `

where :

ΔP = pressure loss
P =inlet pressure
Po = outlet pressure
Po = outlet pressure
ρ = fluid density
Q= fluid volume flowrate
f = Darcy friction factor
L = pipe length
D = pipe inside diameter
Σ K = total fitting K factor

For gas piping with fittings the outlet pressure is calculated by:

`Po = √(P^2 - 16m^2(fd.L / D + ΣK) (mma.SG.ZRoT)/(pi^2D^4) ) `

where :

m = gas mole flowrate
mma = air molar mass
SG = gas specific gravity
Z = gas compressibility factor
Ro = universal gas constant
T = gas temperature

For liquid fittings the outlet pressure is calculated by:

`Po = P - 8 K ρ (Q^2) / (pi^2D^4) `

where :

K = fitting K factor

For gas fittings the outlet pressure is calculated by:

`Po = √(P^2 - m^2K (16mma.SG.ZRoT)/(pi^2D^4) ) `

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CALCULATOR MODULE : Gas Pipeline Pressure Loss From The Darcy Weisbach Equation   ±

Calculate single phase gas pipeline pressure loss using the Darcy Weisbach equation.

`Po = √(P^2 - m^2(fd.L / D + K) ls (16mma.SG.ZRoT)/(pi^2D^4) ) / (es) `
`ss = (z2 - z2) SG.mma.g / (Ro T Z) `
`es = e^(ss) `
`ls = (es^2 - 1) / (ss) `

where :

Po = outlet pressure
P = inlet pressure
fd = Darcy friction factor
L = piping length
D = piping inside diameter
K = total friction loss factor for fittings
m = gas mole flowrategas
mma = air molar mass
SG = gas specific gravity
Z = gas compressibility factor
Ro = universal gas constant
T = gas temperature
g = gravity constant
zi = inlet elevation
zo = outlet elevation
ss = elevation exponent
es = elevation pressure factor
ls = elevation length factor

For low Reynolds numbers Re < 2000, the fluid flow is laminar and the Darcy friction factor should be calculated using the Hagen-Poiseuille laminar flow equation. For high Reynolds numbers Re > 4000, the fluid flow is turbulent and the Darcy friction factor should be calculated using one of the turbulent flow equations. In the transition region 2000 < Re < 4000, the flow is unstable and the friction loss cannot be reliably calculated. The minor loss K factor is used to account for pipeline fittings such as bends, tees, valves etc..

The calculators use the Darcy-Weisbach pressure loss equation with the Darcy friction factor. The Fanning transmission factor combined with the Fanning equation is commonly used for gas flow. The results for the Darcy and Fanning equations are identical provided that the correct friction factor is used.

The gas specific gravity is the ratio of gas density over the density of dry air at base temperature and pressure. The compressibility factor is assumed to equal 1 at the base conditions. The gas specific gravity is proportional to the gas molar mass.

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CALCULATOR MODULE : Gas Pipeline Chemical Dose Rate   ±

Calculate single phase gas pipeline, liquid chemical dose volume fraction, mass fraction, dose volume over gas mole ratio, dose mass over gas mole ratio, and average fluid density.

`Xv = (Vd) / (Vf) `
`Mv = (Md) / (Mf) `
`Rv = (Vg.Xv) / (1 - Xv) `
`Rm = Rv.ρd `
`Vf = Vd + Vg `
`Mf = Md + Mg `
`ρf = Xv.ρd + (1-Xv) ρg `
`Vg = (m Z Ro T) / P `

where :

Xv = dose volume fraction
Mv = dose mass fraction
Rv = dose volume ratio (dose volume:liquid volume)
Rm = dose mass ratio (dose mass:liquid mass)
Vf = total fluid volume
Vd = dose volume
Vg = gas volume (before dosing)
Mf = total fluid mass
Md = dose mass
Mg = gas mass (before dosing)
Vg = gas volume
m = gas moles
P = gas pressure
T = gas temperature
ρf = average fluid density (dosed)
ρd = dose chemical density
ρg= gas density (before dosing)

The average fluid density includes the dosing chemical (combined undosed liquid and dose chemical). The dose chemical is assumed to remain in the liquid phase. The dose quantity can be calculated from either the gas quantity (before dosing), or the total fluid quantity (after dosing). The dose rate can be calculated from either the gas flowrate (before dosing), or the total fluid flowrate:

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CALCULATOR MODULE : Gas Pipeline Fluid Velocity And Flow Rate   ±
CALCULATOR MODULE : API RP 14E Maximum Erosional Velocity   ±

Calculate API RP 14E maximum allowable erosional velocity for platform piping systems.

The fluid density can be calculated for single phase gas, single phase liquid, two phase gas liquid, or three phase black oil (gas oil and water). The erosional velocity is calculated from the fluid density and the C Factor. Equation 2.14 in API RP 14E uses FPS units. The API RP 14E calculators have been factored to use SI units.

For fluids with no entrained solids a maximum C value of 100 for continuous service, or 125 for intermittent service can be used. For fluids treated with corrosion inhibitor, or for corrosion resistant materials a maximum C value of 150 to 200 may be used for continuous service, and upto 250 for intermittent service. For fluids with solids, the C value should be significantly reduced.

Gas oil ratio (GOR) is the ratio of gas moles over oil volume. Gas moles are commonly measured as gas volume at standard conditions (eg SCF or SCM). Water cut is the volume ratio of water in liquid (oil and water).

Reference : API 14E Recommended Practice For Design and Installation of Offshore Production Platform Piping Systems

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CALCULATOR MODULE : Pipeline Flow Rate   ±
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 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 : Two Phase Gas Liquid Viscosity   ±

Calculate dynamic and kinematic viscosity for two phase gas liquids (gas and oil or gas and liquid).

Kinematic viscosity is equal to the dynamic viscosity divided by the density of the fluid. The viscosity of two phase fluids and mixtures can be calculated from the dynamic viscosity and the volume fraction. The gas oil ratio is the ratio of gas moles to oil volume. It is often measured as gas standard volume (scf or scm) per oil volume (barrels, gallons, cubic feet or cubic meters).

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CALCULATOR MODULE : Three Phase Gas Oil Water (Black Oil) Viscosity   ±

Calculate dynamic and kinematic viscosity for three phase black oil (gas oil and water).

Kinematic viscosity is equal to the dynamic viscosity divided by the density of the fluid. The viscosity of two phase fluids and mixtures can be calculated from the dynamic viscosity and the volume fraction.

The gas oil ratio is the ratio of gas moles to oil volume. The gas mass fraction is the ratio of gas mass to total fluid mass. The gas volume fraction is the ratio of gas volume to total fluid volume. Water cut is the ratio of water volume over total liquid volume (equals the water volume fraction in the liquid). Gas volume is dependent on fluid temperature and pressure. Gas oil ratio is often measured as gas standard volume (scf or scm) per oil volume (barrels, gallons, cubic feet or cubic meters).

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CALCULATOR MODULE : Gas Kinematic And Dynamic Viscosity   ±

Calculate dynamic viscosity and kinematic viscosity for single phase gas.

Kinematic viscosity is equal to the dynamic viscosity divided by the density of the fluid. Gas specific gravity (SG) equals the gas molar mass divided by the molar mass of air (28.964 kg/kg-mol).

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CALCULATOR MODULE : Two Phase Fluid Gas Oil Ratio GOR   ±
CALCULATOR MODULE : Two Phase Gas Liquid Density   ±

Calculate fluid density for two phase fluid (oil and gas, or gas and water).

The gas oil ratio is the ratio of gas moles to oil volume. The gas mass fraction is the ratio of gas mass to total fluid mass. The gas volume fraction is the ratio of gas volume to total fluid volume. Gas volume is dependent on fluid temperature and pressure. Gas oil ratio is often measured as gas standard volume (scf or scm) per oil volume (barrels, gallons, cubic feet or cubic meters).

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CALCULATOR MODULE : Three Phase Gas Oil Water (Black Oil) Density   ±

Calculate fluid density for three phase black oil (oil, water and gas).

The gas oil ratio is the ratio of gas moles to oil volume. The gas mass fraction is the ratio of gas mass to total fluid mass. The gas volume fraction is the ratio of gas volume to total fluid volume. Water cut is the ratio of water volume over total liquid volume (equals the water volume fraction in the liquid). Gas volume is dependent on fluid temperature and pressure. Gas oil ratio is often measured as gas standard volume (scf or scm) per oil volume (barrels, gallons, cubic feet or cubic meters).

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CALCULATOR MODULE : Fluid Dosing Rate And Density   ±
CALCULATOR MODULE : Single Phase Gas Density   ±
CALCULATOR MODULE : Two Phase Gas Liquid Heat Capacity   ±

Calculate two phase gas liquid heat capacity.

Fluid heat capacity can be calculated for single phase phase liqui. single phase gas, or combined liquid and gas. Gas oil ratio (GOR) is the ratio of gas moles over liquid volume. Gas moles are commonly measured by standard cubic feet (scf), and stand cubic meters (scm). Gas oil ratio is often measured as gas standard volume (scf or scm) per oil volume (barrels, gallons, cubic feet or cubic meters).

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CALCULATOR MODULE : Three Phase Gas Oil Water (Black Oil) Heat Capacity   ±

Calculate three phase gas oil water (black oil) heat capacity.

Black oil is a three phase mixture of oil, water and gas. Water cut is measured relative to the total liquid volume (gas volume is ignored). Gas oil ratio (GOR) is measured relative to the oil volume at standard conditions (water volume is ignored). Gas oil ratio (GOR) is the ratio of gas moles over liquid volume. Gas moles are commonly measured by standard cubic feet (scf), and stand cubic meters (scm). Gas oil ratio is often measured as gas standard volume (scf or scm) per oil volume (barrels, gallons, cubic feet or cubic meters).

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