Quote (wd1980)

did we consider in stds like API 505, IP 15 that flange connections are within class 0, 1 or 2?

Quote (EI 15-2015)

1.5.4 Source and grade of release
For the purpose of area classification a source of release is defined as a point from which a flammable gas, vapour or liquid may be released into the atmosphere. Three grades of release are defined in terms of their likely frequency and duration:
−− Continuous grade release: A release that is continuous or nearly so, or that occurs frequently and for short periods.
−− Primary grade release: A release that is likely to occur periodically or occasionally in normal operation i.e. a release which, in operating procedures, is anticipated to occur.
−− Secondary grade release: A release that is unlikely to occur in normal operation and, in any event, will do so only infrequently and for short periods, for example as might result from operator error or foreseeable equipment failure, such as a leak resulting from failure of flange gasket, or seal on a pump or valve etc.
The grade of release is dependent solely on the frequency and duration of the release. It is completely independent of the rate and quantity of the release, the degree of ventilation, or the characteristics of the fluid, although these factors determine the extent of vapour travel and, in consequence, the dimensional limits of the hazardous area.

Quote (wd1980)

should the surrounding area be considered in HAC or since it is not a normal operation then I have not to consider this.