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

RISK-BASED INSPECTION METHODOLOGY, PART 5—SPECIAL EQUIPMENT 5-19
Tank ,Thin
D f
is the DF for thinning
d
n
tank
is the diameter of the
D is the storage tank diameter, m (ft)
th
n release hole, mm (inch)
Thin
D fB is the base value of the DF for thinning
E
is the weld joint efficiency or quality code from the original construction code
F is the DF adjustment for AST maintenance per API 653
AM
F LC
is the DF adjustment for lining condition
F is the DF adjustment for online monitoring
OM
F is the DF adjustment for settlement
SM
F is the DF adjustment for welded construction
WD
FC is the financial consequence of environmental clean-up, $
environ
FC is the financial consequence of component damage, $
cmd
FC is the financial consequence of lost production on the unit, $
prod
FC is the total financial consequence, $
total
leak
FC
environ
is the financial consequence of environmental cleanup for leakage, $
rupture
FC
environ
is the financial consequence of environmental cleanup for leakage, $
g is the acceleration due to gravity on earth at sea level = 9.81 m/s 2 (32.2 ft/s 2 )
gff
are the generic failure frequencies for each of the n release hole sizes selected for the type of
n
equipment being evaluated
gff is the sum of the individual release hole size generic frequencies
liq
total
h is the maximum fill height in the storage tank, m (ft)
k
h
h,
prod
is the soil hydraulic conductivity, m/day (ft/day)
k is the soil hydraulic conductivity based on the storage tank product, m/day (ft/day)
k
h,
water
is the soil hydraulic conductivity based on water, m/day (ft/day)
kh,
water− lb
is the lower bound soil hydraulic conductivity based on water, cm/s (in/s)
kh,
water− ub
is the upper bound soil hydraulic conductivity based on water, cm/s (in/s)
ld
n
is the actual leak duration of the release based on the available mass and the calculated
th
release rate, associated with the n release hole size, day
th
Lvol is the total liquid volume for the n release hole size, m 3 (ft 3 )
above,
n
Lvol is the available liquid volume for the
avail,
n
th
n release hole size, m 3 (ft 3 )
Lvol
above,
i
is the total liquid volume above the i th
storage tank course, m 3 (ft 3 )
Lvol
total
is the total liquid volume in the storage tank, m 3 (ft 3 )
LHT
above,
i
is the liquid height above the i th
storage tank course, m (ft)
matcost is the material cost factor
mass is the available mass for release. barrels
N
c
th
n
total
is the total number of storage tank courses
is the representative holes sizes