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

2-148 API RECOMMENDED PRACTICE 581
21.10 Figures
STEP 1: Do administrative
controls prevent pressurizing below
some temperature MPT?
No
STEP 2: Determine T min, the Minimum of:
• Minimum Design Temperature
• MPT by process engineer
Minimum
Design
Temperature
at full
pressurization
Yes
MPT by
process
engineer
Use this MP,
Type of Material
(Carbon Steel
or Low Alloy)
STEP 3: Determine T ref using Table 21.3 and
Exemption Curve Table 21.1.
Exemption
Curve A, B, C,
D
Is ∆FATT
available?
No
Determine ∆FATT using STEP 4,
methods 1)-4).
Material
Minimum Yield
Strength, MYS
Yes
1) Engineering
analysis or
Impact Test
STEP 5:
STEP 4: Calculate MPT – (T ref + ∆FATT)
2) Step Cooling
Embrittlement
(SCE) test
using Equation
2.89
Determine DF Using Table 21.4;
use MPT – (T ref + ∆FATT) in the
lookup
No
PWHT?
Yes
Determine DF Using Table 21.5;
use MPT – (T ref + ∆FATT) in the
lookup
3) J-factor
correlation, X-
bar factor using
Equations 2.90
or 2.91, as
applicable
4) Estimate
∆FATT from
STEP 4, 4)
STEP 6: Determine Damage Factor
using Step 5.
Figure 21.1—Determination of the Low Alloy Steel Embrittlement DF