Section 179.500-10 - Protective housing(a) Safety devices, and loading and unloading valves on tanks shall be protected from accidental damage by approved metal housing, arranged so it may be readily opened to permit inspection and adjustment of safety relief devices and valves, and securely locked in closed position. Housing shall be provided with opening having an opening equal to twice the total discharge area of pressure relief device enclosed.29 FR 18995, Dec. 29, 1964. Redesignated at 32 FR 5606, Apr. 5, 1967, and amended at 66 FR 45390 , Aug. 28, 2001; 67 FR 61016 , Sept. 27, 2002