Impact of Welding Standards on Heat Affected Zone: A Critical Review of the Methods, Consumables, and Environmental Degradation on the Performance of API 5L X52 in Sour Service

Table 4. PWHTEffectiveness Analysis

SSC Threshold vs. HAZ Hardness	Threshold Stress = 45.3 - 0.18 × Hardness	Odds Ratio: 0.82	0.001	0.79	[0.75, 0.89]	Exponential decrease above 240 HV
Microstructure vs. Heat Input	Grain Size = 15.2 × Heat Input⁰·⁵	Exponent: 0.5 ± 0.03	<0.001	0.85	[0.46, 0.54]	Square root relationship
PWHT Effectiveness	Hardness Reduction = 22.3 × log (Time)	Coefficient: 22.3 ± 1.8	<0.001	0.88	[20.2, 24.4]	Logarithmic effectiveness