Session: MF-02-08 Materials for Hydrogen Service-Pipeline Infrastructure 1

Paper Number: 123711

123711 - Fracture Toughness Test Methods for Material Qualification in Gaseous Hydrogen 

The earlier study reported in PVP 2023 by the authors reported findings for an offshore API 5L X60 vintage material. The study found satisfactory mechanical and fracture properties in line with the behaviours to those already published in literature for fatigue crack growth at ∆K above 5 MPa√m and fracture toughness values in-line with other line pipe materials tested in hydrogen. At lower ∆K a new observation of subcritical (Time dependent) crack growth has been found in some microstructures.

This paper focuses particularly on the use of a variety of different small scale test methods to assess the fracture resistance of the material in gaseous hydrogen. The test methods include ASTM E1681 constant load and constant displacement approaches, the ASTM E1820 rising displacement approach and the ASTM F1624 constant hold with additional fatigue pre-conditioning in a structured manner per DNV method (also called ‘constant K’ method). The study work shows similitude in the threshold toughness results with the methods that do not involve pre-conditioning. However, when structured fatigue cycling is preceding monotonic loading the local crack sharpening effect can dramatically reduce the measured threshold for the initiation of crack growth.  

These findings give clarity on the applicability of various test methods and give guidance on the definition of the threshold fracture toughness in the rising displacement ASTM E1820 type tests (the J0mm vs J0.2mm discussion). The findings also demonstrate the importance of utilising fatigue pre-conditioning on susceptible microstructures for assessing for (any) subcritical time dependent crack growth behaviour, in addition to the importance of microstructure discussed in earlier work by the authors in PVP 2023.

Presenting Author: Bostjan Bezensek Shell

Presenting Author Biography: To be provided later

Authors:

Bostjan Bezensek Shell
Sarah Hopkin Shell
Tom Martin Shell
Wim Guijt Shell
Taylor Shie Shell