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[SawsanAli311]

Dear All, 

 

I have a general question.. if we have a fluid which is handled above its flash point.. i.e. the operating temperature is above the flash point.. can flame development occur (in combination with air) with subsequent ignition occur even in absence of an external ignition flame ? I saw several design standards dictating nitrogen blanketing for vessels which process fluids handled above their flash point.. surely the flammability range of the stored liquid is important.. but the relativity of the flash point with respect to the operating temperature also matters for the vapor space combustion i.e. flash point is the temperature which represents the limit of the LEL additionally, In case your vessel is open to atmosphere, would you still provide a flame arrestor on vessels padded with nitrogen to cater for the scenarios of absence of the padding system and preventing flashback from external atmospheric ignition i.e. strike. Or would you prefer not to have a flame arrestor considering its potential blockage with subsequent overpressurization of the vessel. API 2000 7th edition for example Annexure F, allows having nitrogen blanketing in absence of flame arrestors on the condition that blanketing requirement reaches a minimum value of 50% of the computed normal thermal inbreathing rate+the inbreathing due pump out with no pump in. 

 

Appreciate your views..