API RP 77

This standard covers recommended risk assessment and risk management practices to reduce the potential for acute worker hydrocarbon exposures, and related atmospheric risks (i.e., potential oxygen deficiency). Specifically, this recommended practice is limited to onshore production tanks (including flowback tanks) during gauging and sampling, open-top tank sampling, and select tank maintenance activities involving removal or opening of tank appurtenances. While the tools and practices recommended in this document can be useful in other operations, this recommended practice does not specifically apply to downstream, refining, or offshore tank applications.