Fire case Overpressure in Europe

[lizking]

Does anyone know what the allowable overpressure is for the fire case per the European Pressure Equipment Directive (PED)? Their "Guideline 5/2" is clear as mud. Is it 0%, 10% or something greater than 10%?

 

[MortenA]

Its a tricky one - i have been asked to use the 10% by the danish "arbejdstilsynet" for sizing of relief valves - even though i pointed to the guide 5.2 - i think its a mistake because the guide clearly states "The 1,1 PS restriction does not apply to fire. Reasons: The requirement in Annex I section 2.12 for external fire refers to damage limitation, and does not serve the purpose of pressure limiting device in normal operation." but since it was inconsequential for my project i didnt chase it down.

Best regards

Morten

 

[lizking]

Thanks, Morten. In my opinion, you could interpret the "1.1 PS restriction does not apply" two ways: 1. Take the overpressure higher, say to 21% like ASME; or, 2. Don't allow any overpressure (0%).

However, I've seen blanket statements that ALL overpressure scenarios are to be restricted by 110% of PS.

Confusing at best.

 

[MortenA]

The "arbejdstilsynet" are the Danish authorieties on this subject and does as such has the final say in Denmark since the PED is implemented by law in each country and does vary to some degree (you should therefore always consult each countrys own law. I have been told by a Swedish woman from DNV that used to sit in the commision that wrote the PED that the Danish implementation was one of the straight implementations.

Anyway i disagree with the "arbejdstilsynet" but as i said didn't see the need for a confrontation on the subject. Usually i do offshore where they are not the authority.

Best regards

Morten

 

[gerhardl]

Hi, I believe MortenA is giving sound advice.

Locally, at least in all the Scandinavian countries, similar organizations to the danish one have to 'certify' or give final approval to process equipment or factories as a 'whole unified system', including all safety aspects.

In such cases extra precations and safety factors not directly put down in figures in regulations might (I said might) be set down as requirement.

Better to clarify or give in advance warning of your exact interpretation of rules, if in doubt.