API RP 581 - 3rd Ed.2016 - Add.2-2020 - Risk-Based Inspection Methodology

RISK-BASED INSPECTION METHODOLOGY, PART 3—CONSEQUENCE OF FAILURE METHODOLOGY 3-115
Cp
l
is the specific heat of the pool liquid, J/kg-K (Btu/lb- o R)
Dmax is the maximum diameter of the fireball, m (ft)
fb
erate
n
fact
di
Fcyl
n
Fh
n
is the liquid pool mass evaporation rate associated with the n th release hole size, kg/s (lb/s)
is the release magnitude reduction factor, based on the detection and isolations systems
present in the unit
is the radiation view factor for a cylindrical shape, unitless
is the horizontal radiation view factor for a cylindrical shape associated with the n th release hole
size, unitless
Fp
n
is the radiation view factor for a point source associated with the n th release hole size, m -2 (ft -2 )
frac is the mass fraction of the stored fluid that flashes to vapor upon release to the atmosphere
fsh
frac
l
is the mass fraction liquid of the stored fluid under storage conditions
frac is the mole fractions for the i th component in the fluid mixture
mole,
i
frac
ro
frac
v
Fsph
Fv
n
is the rainout mass fraction
is the mass fraction vapor of the stored fluid under storage conditions
is the view factor for a spherical shape, unitless
is the vertical radiation view factor for a cylindrical shape associated with the n th release hole
size, unitless
g is the acceleration due to gravity on earth at sea level = 9.81 m/s 2 (32.2 ft/s 2 )
g is the gravitational constant = 1.0( kg −m) ( N −s 2 ) ⎡32.2( lb ) ( 2
m
− ft lbf
−s
)
c
⎣
⎤
⎦
gff
n
are the generic failure frequencies for each of the n release hole sizes selected for the type of
equipment being evaluated
gff
total
is the sum of the individual release hole size generic frequencies
H is the center height of the fireball, m (ft)
fb
HC
l
HC
s
is the heat of combustion of the liquid fuel for the pool fire calculations, J/kg (Btu/lb)
is the heat of combustion of the stored fluid or mixture, J/kg (Btu/lb)