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

RISK-BASED INSPECTION METHODOLOGY, PART 2—PROBABILITY OF FAILURE METHODOLOGY 2-147
21.9 Table
Table 21.1—Data Required for Determination of the DF—Low Alloy Steel Embrittlement
Required Data
Impact test temperature, °C (°F)
Administrative controls for upset
management (Yes/No)
Minimum operating temperature under
normal, start-up/shutdown, or upset
conditions, °C (°F)
Time in service, years
∆FATT, °C (°F)
Chemical composition of steel (optional)
Screening of materials (Y/N)
SCE specified delta temperature, °C (°F)
Comments
If impact tested. If this is unknown, it should be assumed that impact tests
were not done.
Are there controls and or awareness training to prevent the coincident
occurrence of low temperatures (upset) at or near design pressures?
For low alloy steel embrittlement, this may be the temperature below which
the operating pressure is reduced for purposes of fracture control. If not
known, the temperature should be set to the atmospheric boiling point of
the fluid in the component if the fluid is a liquid.
The number of years in service within the temperature range.
The change in the fracture appearance transition temperature before and
after embrittlement.
Specifically, the %Si, %Mn, %P, and %Sn for 2.25Cr-1Mo and 3Cr-1M0
steels and the %P, %Sb, %Sn, and %As for 1.25Cr-1Mo and 1Cr-1Mo
steels, which contribute to the susceptibility to low alloy steel embrittlement. If
not known, a transition shift will be assumed.
Was the material used for the component screened for susceptibility to low
alloy steel embrittlement by such methods as specifications for steel
composition or specification of a transition temperature requirement in a
step cooling embrittlement (SCE) test.
The delta temperature specified for SCE tests.