IIW White Paper

9 Needs and challenges of major industry sectors for future applications

Another “green topic”, pressure equipment for the wide use of hydrogen as a substitute for fossil fuels, requires a large, international effort. It must be aimed at understanding, characterising and predicting the performance of welded materials in high pressure hydrogen. An effective testing programme first requires identifying objectives and a strategy based on true understanding of the phenomenon and potential damage scenarios. Certainly the residual stresses and microstructural changes caused by welding will make or break hydrogen as a practical alternative. There is no shortage of data on hydrogen embrittlement of high strength steels. They will not be used, however. There is a need for data, appropriate to the specific infrastructural materials (lower strength steels in many situations) and their welds as encountered in the envisioned applications. There is not yet a cohesive engineering database applicable to these likely materials to be employed in long term cyclic contact with hydrogen as part of consumer’s life style in the transportation industry and its supporting infrastructure. The various manifestations of hydrogen embrittlement have been well known and studied for a century. Certainly many hundreds of millions of dollars have been spent on programmes on hydrogen embrittlement research. If new programmes are to make a difference they must be well conceived and lead to more practical knowledge than is currently available. Some of the significant issues are as follows: A mechanistic appreciation of the fundamentals of the materials-environment interaction at the materials surface as affected by stress, stress concentrations, time, temperature, strain rate surface films, gas phase impurities and others. Comprehension of potential effects of materials fabrication and joining technologies that will be employed. Attention to detail so that effective quality assurance programmes may be established for welded construction. Correlation of conventional toughness measures with performance in high pressure hydrogen. An understanding of the role of minor elements on susceptibility to crack growth. Foreign and domestic materials specifications have different aim ranges. Adequate quality assurance/control of materials and processes. The requirements must be based on concepts of where and how hazards may be introduced inadvertently and what and how safety margins need to be developed and justified. The matrix of concerns needs to include properties under conditions resulting from accident, fire, hydrogen contamination, and long term ageing of welded components. 9.5.3 Hot topics The increasing trend to extremely high pressures and temperatures - allowable pressures up to 10,000 bar in food processing, powder metallurgy and waste treatment; allowable metal temperatures up to 1,250 °C in the petrochemical industry and down to –273°C in air separation plants. Unification of codes and procedures for, and better understanding of, residual stress estimates for fitness for service. Utilisation of hydrogen as a “green” alternative to fossil fuels will require understanding, characterisation and prediction of the performance of welded materials in high pressure hydrogen environments. Economic considerations with regard to extension of equipment life, and ecological considerations with regard to leak-tightness and risk reduction. There must be:

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Through Optimum Use and Innovation of Welding and Joining Technologies

Through Optimum Use and In ov tion f Welding and Joining Technologies

Improving Global Quality of Life

Improving Global Quality of Life