Energy transition
As hydrogen is highly combustible, materials need to be selected that are not affected by gas permeation and leakage. Image: Dreamstime
Plug valve sealant compatibility
Findings from another research project were delivered by Mr Ochuko Ifie( Flowserve), who discussed how sealant used in lubricated plug valves had been evaluated for compatibility in hydrogen gas service. Giving due acknowledgement, Mr Ifie noted that the research journey had taken six months, in collaboration with Fraunhofer. Discussing the need to validate compatibility, he drew attention to API 6D Annex M, which states that‘ lubricated plug valves shall be furnished with sealant / lubricant validated for the rated design temperature range of the valve in hydrogen service’ and‘ the sealant / lubricant shall be capable of maintaining viscosity for tight sealing and lubricity for ease of operation in hydrogen service’. Commenting that the hydrogen economy and resulting standards are driving valve qualification requirements, he observed that Flowserve’ s lubricated plug valves have been used in hydrogen gas service for decades, such as in recovery lines in catalytic processes. Methods used during this specific project included rheological investigation, thermogravimetry analysis and differential scanning calorimetry. Test conditions were set to approximate typical hydrogen gas pipeline applications for lubricated plug valves. Three different Flowserve sealants were evaluated. Summing up, Mr Ifie indicated that the impacts of hydrogen gas were not significant enough to influence performance and that sealant stability was maintained after the exposure. In short,‘ The test process effectively qualified Flowserve sealants in hydrogen gas service’.
Hydrogen aircraft
Cryogenic high-performance valves for hydrogen aircraft was the topic discussed by Mr Nozomi Matsumura from KITZ. By way of background, he pointed to Japan’ s Declaration of Carbon Neutrality by 2050 and a NEDO project( New Energy and Industrial Technology Development Organization) for aircraft development. Specifically, KITZ is looking to develop check valves, back-pressure regulating valves, and shut-off valves( ball valve with electric actuators). They are intended for use with liquid hydrogen and lowtemperature hydrogen gas( approx – 253 ° C). As to requirements, he indicated that valves for hydrogen aircraft have to be high performance, compact, lightweight and reliable. Providing more details, he indicated that the check valves would have an inline structure and be capable of working at even very low pressure. Meanwhile, the shut-off valves would require a compact structure without an extension bonnet, yet still be suitable for extremely low-temperature conditions. Looking in detail at the check valve, KITZ are considering the use of ultrathin walls to achieve weight savings. Discussing the prevailing status, Mr Matsumura indicated that following evaluation of the functional prototype, KITZ had moved on to the design, manufacturer and evaluation stage, with the goal of installing the system in actual aircraft.
API Spec 6D, Annex M
Jonathan Geleijns came to the Valve World Conference wearing two hats. First, he is Energy Transition Technologies Manager— SLB. In addition, he is co-chairman API spec 6D, Annex M. And it was in this second capacity that he delivered a presentation outlining API’ s efforts as regards valves for hydrogen service. He started by reviewing key concerns for hydrogen gas. These include: hydrogenrelated material damage, effects on soft materials, sealability, and fire and explosion hazards. Moving to the API task group, he said that the 172 members included end users, valve manufacturers, seal manufacturers and test centers from eleven countries. Quickly going through the main requirements, these include issues such as: specification levels for hydrogen, design validation tests, materials requirements, supplemental acceptance testing, nondestructive examination, quality control, marking, and documentation. Looking at the main requirements for metallic materials, Mr Geleijns discussed topics such as: NACE MR0175 / ISO 15156 compliance, permitted materials, materials requiring additional testing, springs, welding and cladding, bolting, etc.
Deep cryogenic testing
‘ Getting ready for liquid hydrogen – a vision on deep cryogenic testing’ was the topic addressed by Ventil’ s Emiel Lechevallier. Looking at the‘ why’, Mr Lechevallier indicated that liquid hydrogen has a higher energy density per volume compared to gaseous hydrogen. Hence it could be a very useful energy carrier. However, there is a‘ cryo conundrum’, he continued. Factors include: the large temperature drop to transition from cryogenic hydrogen at – 196 ° C and liquid hydrogen at – 253 ° C; the effects of material crimp and tolerances; the fact that the physical properties of the fluid will change, resulting in leakages, not emissions. Ventil is therefore researching the optimum way to test valves intended for liquid hydrogen service. Under development is a system using closed cycle cooling based on helium, with the benefit of only consuming electric energy. This approach, indicated Mr Lechevallier, would facilitate cycle and reliability testing over longer periods of time, without disproportional costs.
Disclaimer: all text based on December 2024 Valve World Conference PowerPoint presentations. Information and insights may have evolved.
56 Valve World June 2025 www. valve-world. net