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Reference: ISH2015_535

Type:
ISH Collection
Title:

Analysis and Experiment on Metal Ablation Protection of the Large Floating Roof Oil Tanks Struck by Direct Lightning

 

Abstracts

Fire is a serious disaster for large floating roof oil tanks and brings great economic losses. The direct effects of lightning on oil tanks are mainly melting or burning at attachment point and could cause large temperature rise. Adopting the experiment method is an effective way to solve the complex problem of metal ablation. In this research, the aluminium alloy 3003 and steel alloy Q235B, which are widely used in oil tanks, are studied with the simulated lightning current. The simulated lightning current is generated by a multiple impulse current generator. The output waveforms are simulated first stroke, continuing current of interval stroke and long continuing current. The amplitudes of the experimental current components are 200kA, 8kA and 400A, respectively. The impacts of lightning waveforms, charge transfer and action integral on metal ablation and the contributions on temperature rise caused by different components of multiple lightning currents are investigated. The temperature rise caused by multiple lightning strokes is estimated. The experimental results on metal ablation show that for both aluminium alloy 3003 and steel alloy Q235B, the long continuing current causes the most serious ablation damage, followed by the continuing current of interval stroke. The first stroke causes little ablation damage. The action integral is meaningless for metal ablation analysis. The ablation depth is closely related to the charge transfer and the ablation area is closely related to the lightning current amplitude. For a constant charge transfer, lightning current with longer duration time causes more serious ablation damage than lightning current with larger amplitude. The temperature rise almost linearly increases with the charge transfer. The temperature rise caused by the long continuing current is much higher than others and could easily lead to the oil tank ignited.
 

File Size: 806,7 KB

Year: 2015

 
 
 
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