Measurement of Fatigue Crack Growth Relationships in Hydrogen Gas for Pressure Swing Adsorber Vessel Steels

Abstract

Hydrogenassisted fatigue crack growth rates (da/dN) were measured for SA516 Grade 70 steel as a function of stressintensity factor range (خ”K) and loadcycle frequency to provide lifeprediction data relevant to pressure swing adsorber (PSA) vessels. For خ”K values up to 18.5 MPa m1/2, the baseline da/dN versus خ”K relationship measured at 1 Hz in 2.8 MPa hydrogen gas represents an upper bound with respect to crack growth rates measured at lower frequency. However, at higher خ”K values, baseline da/dN data must be corrected to account for modestly higher crack growth rates at the lower frequencies relevant to PSA vessel operation.