Internal Inspection. Unless an internal inspection is required by law or by an inspector at the inspector's discretion, a: Hot water boiler requires only an external inspection for certificate purposes; and Pressure vessel requires only an external inspection for certificate purposes. At least 7 days before an internal inspection, the inspector shall notify the owner of the inspection date. The owner of a boiler shall prepare the boiler for internal inspection and hydrostatic test, if necessary, by: Drawing off water and washing the boiler thoroughly; Removing manhole and handhole plates, washout plugs, and inspection plugs in water column connections; Cooling and thoroughly cleaning furnace and combustion chambers; Removing all grates of internally fired boilers; Removing the pressure gage for testing; Disconnecting the pipe or valve at the most convenient point to prevent leakage of steam or hot water into the boiler; Performing the following procedures before opening a manhole or handhole cover and entering any part of a steam-generating unit connected to a common header with other boilers: Close, tag, and preferably padlock: Non return and steam stop valves; and Feed and check valves; Open drain valves or cocks between: Non return and steam stop valves; and Feed and check valves; and After draining the boiler: Close and padlock the blowoff valves; Where practicable, disconnect blowoff lines at a point between pressure parts and valves; and Open all drains and vent lines. The owner of a pressure vessel shall prepare the pressure vessel for inspection to the extent required by the inspector, using the applicable procedures set out in §B of this regulation. Removal of Covering During Inspection. At each annual inspection, brickwork shall be removed, as required by the inspector, to determine the condition of the boiler, headers, furnace, supports, or other parts. Unless the information can be obtained by other means, if boiler or pressure vessel jacketing conceals the longitudinal seams of a shell, drum, or dome, sufficient jacketing, setting wall, or other casing or housing shall be removed to permit: Reasonable inspection of the seams; and Determination of: The size and pitch of the rivets; and Other data necessary to ascertain the safety of the boiler or pressure vessel. When an external inspection discloses evidence of a leak or crack: Sufficient covering shall be removed from the boiler or pressure vessel to permit the inspector to make a safety determination; and If the covering cannot be removed during the inspection, the inspector may order use of the boiler or pressure vessel discontinued until: The covering can be removed; and Proper inspection can be made. Hydrostatic Pressure Test. A hydrostatic pressure test of a boiler or pressure vessel may not exceed: 1-1/2 times the maximum allowable working pressure; or The required test pressure by more than 2 percent. During a hydrostatic test: Each safety valve shall be removed; or Each valve disk shall be held to its seat by a testing clamp, and not by tightening the compression screw on the spring. Water used to apply a hydrostatic test shall have a: Recommended minimum temperature of 70°F; and Maximum temperature of 140°F. When a hydrostatic test is applied to an existing installation to determine: Tightness, test pressure shall equal the release pressure of the safety valve having the lowest release setting; and Safety, test pressure shall equal 1-1/2 times the maximum allowable working pressure. If a boiler or pressure vessel is not properly prepared for internal inspection, or if the owner fails to comply with the requirements for a hydrostatic test as set out in this regulation: The inspector may refuse to conduct the inspection or test; and If the inspector refuses, the chief boiler inspector shall withhold the inspection certificate until the owner complies with the requirements. An inspector is authorized to: Conduct inspections in accordance with Public Safety Article, §12-909, Annotated Code of Maryland; and Review and verify records required by Public Safety Article, Title 12, Subtitle 9, Annotated Code of Maryland, and by Codes referenced in Regulation .01-1 of this chapter.