When a boiler or pressure vessel is operating, a person may not remove, modify, alter, or repair a safety appliance required by these regulations. When a boiler or pressure vessel is not operating and a safety appliance is removed for modification, alteration, or repair the appliance shall be reinstalled in proper working order before the boiler or pressure vessel resumes operation. A safety valve may not be loaded to maintain a working pressure greater than the maximum allowable operating pressure.