Flow And Piping

SECTION 17

Fluid Flow and Piping
Few flow problems can be solved with an acceptable degree of accuracy when using equations designed to fit idealized applications. Flow regimes and associated pressure drops are complex phenomena and require complex equations to predict their relationships. For engineering design purposes, several empirical formulas have been developed to fit particularcircumstances in predicting flow capacity and pressure drop.

FIG. 17-1 Nomenclature A = pipe cross sectional area, ft2 (A = πD2/4) c = sum of allowances for corrosion, erosion, etc., in., Fig. 17-23 C = design parameter used in Hazen and Williams formula, Eq. 17-33 C1 = discharge factor from Fig. 17-8 C2 = size factor from Fig. 17-9 d = internal diameter of pipe, in. do = outside pipe diameter, in. D= internal diameter of pipe, feet E = pipeline efficiency factor (fraction) E′ = longitudinal weld joint factor from ANSI B31.3, Fig. 17-23 E′′ = longitudinal joint factor from ANSI B31.8, Fig. 17-24 ff = Fanning friction factor fm = Moody friction factor (fm = 4.0 ff) fn = single phase friction factor for Dukler calculation, from Eq 17-44 ftpr = friction factor ratio for Dukler calculation, Fig.17-17 F′′ = construction type design factor used in ANSI B31.8, Fig. 17-24 Fpv = volume correction for a non-ideal fluid due to compressibility from Eq 17-13  1/f √ f = transmission factor g = acceleration due to gravity, 32.2 ft/sec2 gc = gravitational constant, 32.2 (ft • lbm)/(lbf • sec2) hL = loss of static pressure head due to fluid flow, feet of fluid H = total energy of a fluid at apoint above a datum, from Eq 17-1 HLd = liquid holdup fraction (Dukler), Fig. 17-18 HLe = liquid holdup fraction (Eaton), Fig. 17-20 HLf = liquid holdup fraction (Flanigan), Fig. 17-19 IL = liquid inventory in pipe, ft3, from Eq 17-57 L = length of line, feet Lm = length of line, miles MW = molecular weight Nx = Fig. 17-16 horizontal coordinate, ft/sec Ny = Fig. 17-16 vertical coordinate, ft/sec NENLv Ngv Nd NL P P1 P2 Pavg Pb Pi ∆P100 ∆Pe ∆Pf ∆Pt q Q = = = = = = = = = = = = = = = = = abscissa of Eaton correlation, Fig. 17-20 liquid velocity number, from Eq 17-53 gas velocity number, from Eq 17-54 pipe diameter number, from Eq 17-55 liquid viscosity number, from Eq 17-56 pressure, psia inlet pressure, psia outlet pressure, psia average pressure, psia, from Eq 17-16 base absolute pressure,psia (ANSI 2530 specification: Pb = 14.73 psia) internal design pressure, psig pressure drop, psi/100 ft equivalent pipe length elevation component of pressure drop, psi frictional component of pressure drop, psi total pressure drop, psi flow rate, gal./min flow rate of gas, cubic feet per day at base conditions liquid volumetric flow rate at flowing conditions, ft3/sec gas volumetric flow rate atflowing conditions, ft3/sec Reynolds number mixture Reynolds number for Dukler calculation, from Eq 17-45 specific gravity of flowing gas (air = 1.0) allowable stress, psi, Fig. 17-23 specified minimum yield strength, psi, Fig. 17-24 thickness, in., Figs. 17-23, 17-24 minimum required wall thickness, in., Fig. 17-23 absolute temperature of flowing gas, °R temperature derating factor used in ANSIB31.8, Fig. 17-24 average temperature, °R, [Tavg = 1/2 (Tin + Tout)] base absolute temperature, °R (ANSI 2530 specification: Tb = 520°R) single phase fluid velocity, ft/sec superficial gas velocity, ft/sec, from Eq 17-36 superficial liquid velocity, ft/sec, from Eq 17-35 mixture velocity, ft/sec, from Eq 17-46

QL = Qg = Re = Rey = S S′ S′′ t tm T T′′ = = = = = = =

Tavg = Tb = V Vsg VsL Vm = == =

17-1

FIG. 17-1 (Cont’d) Nomenclature W = mass flow, lb/hr XA = Aziz fluid property correction factor (horizontal axis, Fig. 17-16) YA = Aziz fluid property correction factor (vertical axis, Fig. 17-16) Y′ = coefficient found in Table 304.1.1, ANSI B31.3, Fig. 17-23 Zavg = average compressibility factor Ze = pipeline vertical elevation rise, ft ε = absolute roughness, ft λ = flowing...