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Special Topic : Green Applications
Stainless Steels in Hydrogen Transition of Gas Grid
Stainless steel is a key material in the energy industry , and its properties make it ideal for applications such as hydrogen transport . As governments around the world set ambitious net-zero goals , the use of hydrogen as a clean fuel is becoming increasingly important to reduce carbon emissions in the transportation sector . In fact , many countries have included hydrogen as a central element in their climate change strategies for transportation . For instance , the European Union aims to have 40GW of renewable hydrogen electrolyzers by 2030 , and hydrogen is expected to play a major role in achieving its decarbonization goals . Governments are investing heavily in the development of hydrogen technologies for transportation , and significant progress has been made in recent years . Research groups like the Hydrogen Council and H2ME have conducted extensive trials to investigate the feasibility and benefits of using hydrogen as a fuel for transportation , and their findings have been encouraging . These developments present an opportunity for the stainless steel industry to play a key role in the energy transition by providing the materials needed for hydrogen transport infrastructure .
By Tuncay Kurtulan , Senior Materials Engineer , OGC Energy
Preventing Hydrogen-Induced Damage
Natural gas distribution networks typically operate at relatively low pressures and temperatures , which are not expected to cause significant material degradation in the presence of hydrogen . Non-metallic and metallic parts have been evaluated for their performance within a temperature range of 0 to 65 ° C and a maximum pressure of 100 bar , which represents the common operating conditions under investigation .
Although guidelines like API RP 941 offer valuable recommendations for the safe utilization of materials in high-pressure and high-temperature hydrogen environments , it is important to note that these guidelines specifically ad- dress the risk of high-temperature hydrogen attack ( HTHA ) and other damage mechanisms that typically occur at temperatures above approximately 200 ° C . These guidelines are particularly applicable to refinery settings where such risks are present .
While the effects of hydrogen on the degradation of soft and other materials in natural gas distribution networks are generally considered negligible , it is crucial to assess the compatibility of materials for hydrogen transport infrastructure to ensure safe and reliable operations .
The term ‘ hydrogen embrittlement ’ is commonly used to describe different damage mechanisms that occur when metals absorb hydrogen .
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The recognized mechanisms of hydrogen-induced damage such as hydrogen stress cracking ( HSC ) can occur in susceptible materials after hydrogen absorption . Sulfide stress cracking ( SSC ) is another form of HSC where H 2
S exposure is required for hydrogen adsorption . Galvanically induced hydrogen stress cracking ( GHSC ) and hydrogen-induced cracking ( HIC ) are typically only susceptible to rolled products . The shape and amount of MnS inclusions are the decisive factors for HIC . Stress-oriented hydrogen-induced cracking ( SOHIC ) is the same damage mechanism as HIC , however , the HIC cracks are aligned according to stress . Lastly , high-temperature hydrogen attack ( HTHA ) occurs at temperatures above 204 ° C .
It is crucial to consider these mechanisms in the design and selection of materials for hydrogen transport infrastructure to prevent hydrogen-induced damage and ensure safe and reliable operations .
Understanding the Risk of Hydrogen Embrittlement
Special attention should be given to rolled products and materials containing MnS inclusions , which are susceptible to HIC and SOHIC . In addition , GHSC is a potential risk for materials that are in contact with dissimilar metals or alloys . By taking these factors into account and selecting appropriate materials and designs , the risk of hydrogen-induced damage can be minimized , and hydrogen can be safely and effectively transported .
This statement implies that hydrogen stress cracking ( HSC ) is a credible failure mechanism for hydrogen gas , and there may be a few uncommon cases where hydrogen-induced cracking ( HIC ) occurs .
The risk of hydrogen embrittlement can be associated with the expected hydrogen concentration . With that in mind , the expected hydrogen concentration in the steel that is subject to 81 bar H 2 is calculated and compared with other steels that are subject to different hydrogen charging environments within the table reproduced from CEN / TR 17797 .
Based on the information presented in Table 1 , the hydrogen pressures corresponding to the measured concentrations were calculated . Assuming a maximum pressure of 81 bar in natural gas pipelines , the estimated hydrogen concentration in steel was found to be 0.25 ppm , which suggests that the impact of hydrogen gas at this pressure can be deemed insignificant . However , it is important to note that metals highly susceptible to hydrogen stress cracking ( HSC ) may still undergo cracking even when exposed to trace amounts of hydrogen .
The NACE MR 0175 / ISO 15156 standards offer comprehensive guidance to restrict hydrogen-enhanced damage mechanisms by specifying material limits for sour service . However , these standards do not include specific mandates for partial pressures below 0.05psia ( 0.3 kPa ). Even though hydrogen transportation equipment and piping are not required to conform to sour service standards , certain concerns remain pertinent for any environment .
6 Stainless Steel World Americas - December 2023 | www . ssw-americas . com