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

3-124 API RECOMMENDED PRACTICE 581
Table 5.2—Surface Interaction Parameters with Liquid Pools
Surface
Thermal Conductivity,
k
surf
(Btu/hr-ft- o R)
Thermal Diffusivity,
(ft 2 /s)
α
surf
Surface Roughness,
(unitless)
Concrete a 0.53 4.48 × 10 −6 1.0
Soil (average) 0.56 4.94 × 10 −6 3.0
Soil (sandy, dry) 0.15 2.13 × 10 −6 3.0
X
surf
Soil (moist, 8 %
water, sandy)
0.34 3.62 × 10 −6 3.0
NOTE Cremer and Warner Ltd. [11] .
a
Use as default.
Table 5.2M—Surface Interaction Parameters with Liquid Pools
Surface
Thermal Conductivity,
k
surf
(W/m-K)
Thermal Diffusivity,
(m 2 /s)
α
surf
Surface Roughness,
(unitless)
Concrete (Note 1) 0.92 4.16 × 10 −7 1.0
Soil (average) 0.96 4.59 × 10 −7 3.0
Soil (sandy, dry) 0.26 1.98 × 10 −7 3.0
X
surf
Soil (moist, 8 %
water, sandy)
0.59 3.36 × 10 −7 3.0
NOTE Cremer and Warner Ltd. [11] .
a
Use as default.
Table 5.3—Event Probabilities
Release Type
Fluid
Phase
Probability of Immediate
Ignition, Given Ignition
At Ambient
Temperature
poii
amb
n
At AIT
ait
poii
Probability of VCE or Flash Fire,
Given Delayed Ignition
VCE,
pvcedi or
ln ,
pvcedi
vn ,
Flash Fire,
pffdi or
ln ,
pffdi
vn ,
Continuous Liquid 0.20 1.00 0.25 0.75
Continuous Vapor 0.50 1.00 0.50 0.50
Instantaneous Liquid 0.20 1.00 0.125 0.875
Instantaneous Vapor 0.10 1.00 0.25 0.75