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

RISK-BASED INSPECTION METHODOLOGY, PART 3—CONSEQUENCE OF FAILURE METHODOLOGY 3-119
pvcedi
is the probability of VCE given a delayed ignition
pvcedi is the probability of VCE given a delayed ignition of a release of a flammable liquid associated
ln ,
with the n th release hole size
pvcedi is the probability of VCE given a delayed ignition of a release of a flammable vapor associated
vn ,
with the n th release hole size
P
atm
is the atmospheric pressure, kPa (psia)
P is the bubble point pressure of the released fluid at the ground temperature, kPa (psia)
bg ,
P
B
is the component or equipment burst pressure, kPa (psia)
Pr
P
s
is the probit value, typically set at 5 (50 % probability)
is the storage or normal operating pressure, kPa (psia)
P is the side-on overpressure associated with the n th release hole size, kPa (psia)
SO,
n
P
w
is the atmospheric water partial pressure, kPa (psia)
Psat
s
is the saturation pressure of the stored fluid at operating (storage) temperature, kPa (psia)
fball
Qrad is the total energy flux radiated from a fireball, W/m 2 (Btu/hr-ft 2 )
jet
Qrad
n
is the total energy radiated from a jet fire associated with the n th release hole size, W (Btu/hr)
pool
Qrad is the total energy flux radiated from a pool fire associated with the n th release hole size, W/m 2
n
(Btu/hr-ft 2 )
r is the pool radius, calculated for each of the n release hole sizes selected, m (ft)
pn ,
R
is the universal gas constant = 8314 J/(kg-mol-K) [1545 ft-lbf/(lb-mol-°R)]
R is the pool fire radius, calculated for each of the n release hole sizes selected, m (ft)
pf , n
RH is the atmospheric relative humidity, %
rate is the flammable liquid portion of the adjusted or mitigated discharge rate used in the
flam
ln ,
consequence calculation associated with the n th release hole size, kg/s (lb/s)
flam
rate is the flammable portion of the adjusted or mitigated discharge rate used in the consequence
n
calculation associated with the n th release hole size, kg/s (lb/s)
rate is the flammable vapor portion of the adjusted or mitigated discharge rate used in the
flam
vn ,
consequence calculation associated with the n th release hole size, kg/s (lb/s)