I want to check is it necessary to use lightening for external floating roof or not and when? Media in tank is NAPHTHA.
As per article 7.2.2 ,chapter 7 ,NFPA 780 if tank is tight seal and if consider other condition which is mentioned in this paragraph, lightening is not necessary, But what is meaning of tight seal? Actually we don't have any floating roof tight seal and if use best roof seal,leg seal , .... emission is unavoidable and we can only minimize it,therefore we have to use lightening.
It means that for all external floating roof storage tanks we have to use lightening without any choice.
Would you please clarify it?