29 CFR §1960.31

1. (a)The Secretary or the Secretary's representatives are authorized to conduct, when the Secretary deems necessary, announced or unannounced inspections in the following situations:
   1. (1)Where an agency has not established occupational safety and health committees or where committees no longer operate in conformance to the requirements of subpart F of this part;
   2. (2)In response to a request from half the membership of record of any certified safety and health committee; and
   3. (3)In response to an employee's report of an imminent danger situation, where there is a certified committee, but where the Secretary determines that neither the agency nor the committee has responded to the employee.
2. (b)The Secretary's inspectors or evaluators are authorized: to enter without delay, and at reasonable times, any building, installation, facility, construction site, or other area, workplace, or environment where work is performed by employees of the agency; to inspect and investigate during regular working hours and at other reasonable times, and within reasonable limits and in a reasonable manner, any such place of employment, and all pertinent conditions, structures, machines, apparatus, devices, equipment, and materials therein, and to question privately any employee, any supervisory employee, and/or any official in charge of an establishment.
3. (c)The Secretary may also make scheduled inspections as an integral part of OSHA's evaluation of an agency's safety and health program in accordance with subpart J of this part.
4. (d)OSHA inspections shall follow the general format set forth for agency inspections in other applicable parts of this subpart.