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Explore a temperature-controlled mechanical test facility ensuring safe materials performance in hydrogen at 1000 bar. Learn about the impact of Hydrogen Environment Embrittlement (HEE), testing parameters, system designs, safety measures, and operating procedures.
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A temperature controlled mechanical test facility to ensure safe materials performance in hydrogen at 1000 bar R.I. Hammond R.J. Pargeter (ruth.hammond@twi.co.uk)
Safe storage • Liquid / solid / gas • Need materials which are resistant to gaseous hydrogen for all • Hydrogen embrittlement.
Hydrogen embrittlement • Below 100°C with no straining generally no problem • But strain in the presence of hydrogen leads to Hydrogen Environment Embrittlement (HEE) • HEE affects low cycle fatigue, tensile, toughness.
Testing in high pressure hydrogen • Most data available are statically loaded • HEE only observed if strain in hydrogen • HEE affected by • Strain rate • Temperature • Pressure.
Design and build of new facility • 1000 bar • 99.9999% hydrogen • -150°C to +85°C • Measure • LCF • Tensile • Toughness • Current vessel • 500 bar • 99.9999% hydrogen • Ambient to +85°C
Four strands to project • Equipment design • Physical protection • System design • Operating procedures.
Equipment design • Pressure vessel • National codes • Materials.
Physical protection • Plexiglas roof • Reinforced walls • Test cell: spark free • Blast doors • Hydrogen sensors
System design (1) • PLC • Purge and pressurisation cycles • Safety: never a flammable mixture • Purity: 0.000 001% contaminants
System design (2) • Interlocks • Prevent pressurisation • Trigger automatic shut-down • Test cell door closed • Pressure vessel closed • Hydrogen detectors • Fire detectors • Emergency stop buttons
System design (3) • Hydrogen detectors • Low: 400 ppm (alert operators) • High: 1000 ppm (triggers shut-down) • Automatic shut-down • High hydrogen • Fire alarm • Emergency stop button • Power cut (UPS keep safety systems running)
System design (4) Solenoid valves • Shut down • Stop booster • Close valves on bottles • Shut down and vent • Vents • Purge vessel
System design (5) • Autodiallers • Safety aspects regarding hydraulics • Pneumatics: compressed air run in thin plastic tubes around lab, designed to melt if there is a fire. Low air pressure will trigger shut-down.
Operating procedures • Checklist for routine operation • Unusual operation needs special risk assessments • Skilled operators • Compressed gases • Flammable/explosive • Servo-hydraulic equipment.
Conclusions • For a safe hydrogen economy • Need safe, economical materials and fabrication methods • TWI already has facility to carry out mechanical tests at 500 bar but are extending this to 1000 bar over a temperature range of -150°C to +85°C