In a secure building located a safe distance away from the main buildings at TWI’s headquarters can be found TWI’s high-pressure hydrogen testing facility.
Behind its blast doors, this building houses two pressure vessels capable of carrying out mechanical testing on components exposed to pressurised hydrogen gas at temperatures ranging from -50°C to +85°C. One can generate pressures up to 450 bar – the other up to 1000 bar.
While in these atmospheres, parts can be exposed to compressive and tensile loads, either statically or cyclically at frequencies up to 5Hz. The facility can also be used for hydrogen pre-charging, in which components are exposed to hydrogen gas at high pressures and temperatures for extended periods.
Supported by a complete range of analytical equipment including scanning electron microscopes (SEMs), TWI uses the facility to provide detailed analyses of the behaviour of materials during exposure to hydrogen gas.
Analytical capability also extends to measuring materials’ hydrogen content. Coupled with high-temperature charging, this data reveals materials’ susceptibility to internal hydrogen embrittlement– information essential for applications in sectors including power, aerospace and automotive.
Single client projects currently underway
TWI is currently running several projects using its high-pressure hydrogen testing facility for aero engine companies:
- Tensile tests on a martensitic stainless steel at ambient temperature, at both ambient pressure and 200 bar. The work will include hardness testing before and after the hydrogen exposure, SEM fractography and hot desorption hydrogen content analysis.
- Hydrogen charging and tensile testing of specimens of various alloys in 300 bar hydrogen at both ambient temperature and -50°C.
- Mechanical testing of ball bearings in rotation, using a test assembly designed and manufactured by TWI especially for this project. Testing will take place in high-pressure hydrogen at room temperature and will capture data including preload force before and after testing and the friction torque of the bearings.
The future: a unique new test rig for the aerospace industry
With a decade of hydrogen testing behind it and such specialised equipment, TWI has become a trusted partner for companies from industries including aerospace, automotive and steelmaking.
Recently, however, Industrial Members in the aerospace sector have been expressing interest in new test types that cannot be conducted using the existing equipment. TWI, with its history of creating bespoke test rigs, has responded by launching a joint industry project to explore the feasibility of constructing a unique new test vessel capable of carrying out a greater range of tests.
The proposed vessel would support temperatures exceeding 1000°C and pressures up to 1000 bar, with mechanical test types available including tensile, fatigue crack growth rate, strain-controlled low-cycle fatigue, fracture toughness, cyclical at 20Hz, and testing with a negative load ratio.
If found to be viable, the new test system will enable tests to be conducted that provide industry with enhanced assurance of component performance. However, the team building such a rig would have to overcome a large number of potential design issues.
These include the demands the high pressures, temperatures, and test frequencies would place upon the pressure sealing system; the increased potential for hydrogen diffusion, attack and embrittlement; the challenges of implementing associated instrumentation; and the need to incorporate dedicated heating and cooling systems.
The joint industry project will conclude next year.
In a separate development, TWI is also exploring the possibility of adapting its test facility to enable the study of material performance in liquid hydrogen environments. This would address the needs of Members in the space and automotive sectors.
For more information on either of these proposals, or about TWI’s hydrogen testing services, contact us.