30 CFR 56.14112 - Construction and maintenance of guards.
(a) Guards shall be constructed and maintained to -
(1) Withstand the vibration, shock, and wear to which they will be subjected during normal operation; and
(2) Not create a hazard by their use.
(b) Guards shall be securely in place while machinery is being operated, except when testing or making adjustments which cannot be performed without removal of the guard.