Section 51. An engineer’s or fireman’s license shall be so placed in the engine or boiler room of the plant operated by the licensee as to be easily read. The person in charge of a stationary steam boiler upon which the safety valve is set to blow off at more than twenty-five pounds pressure to the square inch, except boilers in private residences, boilers in apartment houses of less than five apartments, boilers under the jurisdiction of the United States, boilers used for agricultural purposes exclusively, and boilers of less than nine horse power, shall keep a daily record of the boiler, its condition when under steam, and of all repairs made and work done on it, upon forms to be obtained upon application to the department. These records shall be kept on file and shall be always accessible to the chief and inspectors of the division.