FITOK Specialized Products Contribute to Safe and Sound Hydrogen Applications
To alleviate the global warming caused by accumulated greenhouse gas emissions, major economies in the world are committed to achieving the goals of "peak carbon emissions" and "carbon neutrality". Hydrogen, as one of the clean energy sources to replace traditional fossil energy, whose applications are regarded as the main technology direction of the future energy revolution, is therefore gaining increasing attention. Among the many applications, hydrogen fuel cell vehicles and hydrogen refueling stations are in the spotlight of governments and the industry. For instance, both China and Germany released strategic plan on the development in this field.
With the rapid development of hydrogen fuel cell vehicles and the continuous growth of hydrogen refueling stations and other infrastructure construction, common problems in hydrogen applications such as easy leakage, hydrogen embrittlement, and high pressure and low temperature working conditions are also becoming more and more prominent, and how to ensure the safety and reliability of hydrogen systems has become one of the key concerns in the industry. Therefore, selection of suitable products with high safety in different applications is the optimal solution for a safe and reliable hydrogen system.
Raw materials and hydrogen embrittlement resistance
Hydrogen embrittlement is a phenomenon in which hydrogen atoms enter the lattice voids of a metal and move diffusely, causing cracks in the material at the defective location after the atoms have recombined or reacted with other substances to form gaseous molecules, resulting in rapid volume expansion leading to cracks at this location. The hydrogen embrittlement cannot be eliminated once it occurs, so it can only be prevented.
Experiments have proven that stainless steels with nickel content greater than 12% and nickel equivalent not less than 28.5% have excellent resistance to hydrogen embrittlement. FITOK has developed the raw material of enhanced-316/316L (designator SH) for hydrogen applications in accordance with industry standards, which has good resistance to hydrogen embrittlement under high pressure and can meet the requirements of various international standards.
O-ring: low temperature and pressure cycle
Low temperature: Hydrogen needs to be pre-cooled before being charged to the fuel cell vehicle to prevent the risk of tank rupture due to exothermic expansion, and low temperatures can cause the O-rings to lose elasticity and thus lead to sealing failure.
Pressure cycle: From the filling of hydrogen to the pressure relief, the non-metallic O-rings of valves and fittings will undergo repeated pressure changes under 0 MPa to the maximum working pressure, and the small molecules of hydrogen will leak into the inside of O-rings under violent pressure changes, and the hydrogen molecules make the O-ring surface blister or even crack under the violent pressure change.
FITOK provides low-temperature O-rings compatible with hydrogen applications to products suffixed with -H2 and -EC79, which maintain consistent high reliability under extremely harsh working conditions.
Sealing and vibration resistance
Hydrogen’s small molecules are easy to leak and may cause safety accidents. At the same time, hydrogen compressors are one of vibration sources, thus require fittings and valves with excellent vibration resistance. FITOK tube fittings, manufactured with special customized high nickel and high chrome raw materials, after advanced design and manufacturing process as well as hardening treatment to rear ferrule surface, boast excellent sealing and vibration resistance performance in extreme environment.
FITOK tube fittings with EC79 type approval for hydrogen-powered motor vehicles: for 35 MPa application (FITOK 6 series) and for 70 MPa application (FITOK 20D series). Products with this certification are specially marked to reflect the approval.
If UN/ECE R134, ANSI HGV 3.1 and etc. certificate or test report is required, please contact FITOK.
FITOK products improve quality from raw materials and design, and when installed correctly, they can protect the safety of hydrogen system in all aspects. For specific installation steps, please refer to the installation instructions (6 series tube fittings and 20D series tube fittings) for the products. FITOK also provides customers with product installation training and on-site installation guidance to help builders master the correct installation method of the product.