API RP 2217A-2017

This Recommended Practice provides guidance for safely entering and working within and near confined spaces that have inert atmospheres. API 2217A applies to confined spaces that have been intentionally purged with an inert gas until:

— the oxygen level in the vapor space is too low to support combustion, and

— any gases in or at the point of discharge from the confined space are deficient in oxygen such that the mixture is not flammable.

Typical inert entry work in the petroleum and petrochemical industry includes, but is not limited to work to service or replace catalyst in reactors and work in confined spaces where the flammable or toxic atmosphere cannot be removed or made safe by another method (such as atmospheric ventilation).