PSI - Issue 41

Chouaib Zeghida et al. / Procedia Structural Integrity 41 (2022) 384–393 Zeghida Chouaib et al. / Structural Integrity Procedia 00 (2022) 000–000

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Fig. 3. Stress Distribution, Deformation, and Temperature Distribution at the Time of IHSI Application.

It appears that the post-IHSI residual stresses can be adequately described as axisymmetric with a linear through wall gradient. For a given pipe size and thickness, such a spatial distribution can be characterized by a single number, such as the value of the stress at the ID. The results in (Failure Analysis Associates, 1990) indicate that the statistical distribution of the ID residual stress is normally distributed and no consistent variation of the mean and standard deviation with pipe size. 4. Numerical Examples To simulate initiation and growth of cracks in the weld by stress corrosion mechanism, the material properties required for stress corrosion crack initiation and growth for 304 steel are hard-wired in the code. Stress corrosion properties for 304 are selected in this case. Table1. The major inputs.

Pipe Geometry

IDØ = 300 mm Wall Thickness = 30 mm

Stresses

Deadweight = 6.65 MPa Deadweight + Thermal Expansion = 56.14 MPa Operating Pressure = 45.15 MPa Oxygen at Plant Start-Up = 8 ppm Oxygen at Steady-State Operation = 0.2 ppm Water Temperature at Steady-State = 288 °C

Water Chemistry and Conditions that affect SCC

Duration of Plant Heat-Up = 5 hrs Coolant Conductivity = 0.2 µs/cm Mean = 296 MPa Standard Deviation = 29 MPa

Flow Stress

SCC Properties

AISI 304 Stainless Steel implemented in PRAISE

The only load cycle used is the heat-up/cooldown cycle. Failure criteria used is the net-section stress exceeding the flow stress. Pre-service inspection and in-service inspection are considered in the analysis.