Session: CS-02-01 Hydrogen Effects on Material Behavior for Structural Integrity Assessment (Joint with MF-2) - Applying ASME Codes to Material Selection

Paper Number: 105732

105732 - Comparison of Design Approaches on the Design Lifetime Prediction of Gaseous Hydrogen Storage Tanks 

In the context of energy transition, green hydrogen will play a major role as an energy carrier and storage medium in many industry sectors. Hence, existing transport and storage applications must be proofed for their hydrogen readiness as well as new technologies must be developed for establishing a viable infrastructure for the expected amounts of hydrogen. The gaseous medium is mainly stored in storage tanks, which for cost reasons are often made of low alloy ferritic pressure vessel or pipeline steels. Frequent filling and emptying results in cyclic loading of these components and the hydrogen exposure can lead to hydrogen embrittlement in critical locations, e.g. at material inhomogeneities or welds, which may result in a reduced component lifetime. The effect of hydrogen embrittlement must be considered in the assessment of existing and in the design of new storage tanks. For safe design and operation, appropriate lifetime approaches are essential, which allow reliable and accurate predictions of the expected lifetime of hydrogen storage tanks and of the infrastructure.

The ASME B31.12 is a worldwide accepted standard for the design and operation of gaseous hydrogen pipelines. The fracture-mechanics based approach for lifetime assessment assumes an initial, axially oriented, semi-elliptical defect at which crack initiation and hydrogen-assisted fatigue crack growth occurs due to changes in operating pressure. In addition to quasi-static fracture mechanics parameters (e.g. threshold value for fracture toughness in hydrogen K_IH), material state-specific fatigue crack growth curves have to be experimentally determined in gaseous hydrogen. Based on the crack growth behavior, the fatigue lifetime is calculated until a certain end-of-life criterion (e.g. a critical crack depth with regard to the wall thickness) is reached.

The German AD 2000 code, which is compliant with the European Pressure Equipment Directive (2014/68/EU), uses a crack initiation-based approach and the fatigue lifetime is calculated as the number of cycles up to crack initiation of a technical crack (ca. 1-2 mm). In the bulletin S2, the influence of gaseous hydrogen on the fatigue lifetime of ferritic and austenitic steels is assessed from conservatively derived S-N curves and by reduction factors, which are calculated depending on the material strength (e.g. yield strength at room temperature) for non-welded pressure vessels or for vessels with different weld types. Besides, the influence of mean stress, temperature, surface roughness and wall thickness are considered in the lifetime prediction of the AD 2000 code.

Stationary tubular hydrogen storage tanks often consist of parallel connected short pipes. Therefore, in addition to the assessment of the hydrogen influence on the lifetime according to the ASME B31.12 code applying for pipelines, hydrogen storage tanks can be also considered due to regulatory aspects as pressure vessels and following the AD 2000 code. In this work, a comprehensive study for the use case “hydrogen storage tank” is performed, where the influences of different input parameters (e.g. the initial crack depth, crack aspect ratio, operating pressure scenarios) on the lifetime prediction according to the ASME B31.12 code are determined. In addition, the impact of the underlying fatigue crack growth law and method for the stress intensity factor calculation is also demonstrated. The results of the two different design philosophies from the ASME B31.12 and AD 2000 codes are compared and differences in the allowable number of loading cycles for the lifetime prediction of hydrogen storage tanks are discussed.

Presenting Author: Carl Fischer Fraunhofer Institute for Mechanics of Materials IWM

Presenting Author Biography: Since 01/22 Researcher at Fraunhofer IWM in the group "Lifetime Concepts for Hydrogen Applications"
Since 10/15 Researcher at Fraunhofer IWM in the group "Lifetime Concepts, Thermomechanics"

Current activities:
- Investigation of hydrogen embrittlement on metallic materials
- Development of lifetime concepts including hydrogen embrittlement
- Finite element analyzes and lifetime modeling of components
- Finite element analyzes on plasticity-induced crack closure

Authors:

Carl Fischer Fraunhofer Institute for Mechanics of Materials IWM
Heiner Oesterlin Fraunhofer Institute for the Mechanics of Materials IWM
Thorsten Michler Fraunhofer Institute for the Mechanics of Materials IWM