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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.
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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