All areas in which industrial radiography is being performed must be conspicuously posted as required by Sec. 20.1902(a) and (b) of this chapter. Exceptions listed in Sec. 20.1903 of this chapter do not apply to industrial radiographic operations. [62 FR 28963, May 28, 1997, as amended at 66 FR 64738, Dec. 14, 2001]