No material or energy that may create a hazardous condition shall be permitted within the confined space. Lines shall be isolated by blanking, double blocking and bleeding, electrical lockout / tagout and blocking or disconnecting mechanical linkages in such a manner as to prevent inadvertent reconnection.
Work involving the use of flame, arc, spark or other source of ignition is prohibited within a confined space (or any adjacent space) which contains, or is likely to develop, dangerous air contamination due to flammable and/or explosive substances unless the following safety requirements are is in place:
- An inert atmosphere, using gases such as nitrogen, is used to prevent the ignition and the oxygen concentration is maintained at less than 10% of the concentration which supports combustion.
- Sufficiently frequent testing of the oxygen content is performed to ensure that the oxygen remains less than 10% of the concentration which supports combustion.
- Employees in the work area utilize the appropriate personal protective equipment including air-supplied respirators or self-contained breathing apparatus (SCBA) as required.