Environmental factor always 0.3 or how often do you commonly use lower

[jamesbanda]

i've always used 0.3 as the lagging/insulation factor..(And per company policy) but i'm finding many references to lower factors being used and in API521 is shows them..

so.. can i ask whats your policy (s).. and do you often use lower than 0.3 and why / how to do control lagging on/off in shutdowns etc..

 

[chemjock]

Always use 1 now. Can't assume the insulation will stay on in a fire with fire monitors knocking it off.

 

[don1980]

James,

There are two acceptable methods for calculating the heat input due to fire exposure. One is NFPA-30 and the other is API 521. Both methods are widely regarded as acceptable, but the calculations are different...they generate different heat input values. For vessels that have fire resistant insulation, the NFPA-30 methodology is more conservative.

NFPA-30 uses a fixed value (0.3) for the insulation credit factor. In the API 521 method, the insulation credit is a calculated value, based on the thermal conductivity and thickness of the insulation. Commonly, this will result in a credit factor < 0.1.

In my experience, some companies have their own minimum value, and other don't. There's no consensus.