D.C. Code § 2-111: Right of entry for inspection.

The Boiler Inspector and his assistants shall have the right to enter, in the performance of his or their duties, at all reasonable hours, all premises on which a steam boiler or unfired pressure vessel is being installed, operated, or maintained, and it shall be unlawful for any person to deny admittance to any such Inspector or assistant or to interfere with him or them in the performance of his or their duties.