Code of Maryland Regulations
Title 09 - MARYLAND DEPARTMENT OF LABOR
Subtitle 12 - DIVISION OF LABOR AND INDUSTRY
Chapter 09.12.01 - Board of Boiler Rules
09.12.01.12 - Heating Boiler - Existing Installation: Miscellaneous
09.12.01.12. Heating Boiler - Existing Installation: Miscellaneous
A. Feedwater Connection.
(1) Feedwater, make-up water, or water treatment:
(a) Shall be introduced into a boiler through:
(i) The return piping system, or
(ii) An independent feedwater connection that does not discharge against a part of the boiler exposed to direct radiant heat from the fire;
(b) May not be introduced through an opening or connection provided for:
(i) Inspection or cleaning,
(ii) Safety valve,
(iii) Safety relief valve,
(iv) Surface blowoff,
(v) Water column,
(vi) Water gage glass,
(vii) Pressure gage, or
(viii) Temperature gage.
(2) Feedwater pipe shall have a:
(a) Check valve near the boiler; and
(b) Stop valve or cock between the check valve and the boiler or return pipe system.
B. Pressure or Altitude Gage.
(1) A hot water boiler shall have a pressure or altitude gage connected to the boiler or its flow connection so that it cannot be shut off from the boiler except by a cock with a tee or lever handle:
(a) Placed on the pipe near the gage; and
(b) With the handle parallel to the pipe in which it is located, when the cock is open.
(2) The scale on the dial of a pressure or altitude gage shall be graduated to indicate pressures from 1-1/2 to 3 times the maximum allowable working pressure.
(3) Piping or tubing for a pressure or altitude gage connection smaller than 1 inch pipe size shall be of nonferrous metal.
C. Steam Gage.
(1) A steam boiler shall have a steam gage connected to its steam space, water column, or steam connection by a siphon or equivalent device on the exterior of the boiler.
(2) A siphon shall be:
(a) Of sufficient capacity to keep the gage tube filled with water; and
(b) Arranged so that the gage can be shut off from the boiler only by a cock with a tee or lever handle:
(i) Placed in the pipe near the gage, and
(ii) With the handle parallel to the pipe in which it is located, when the cock is open.
(a) The scale on the dial of a steam gage shall be graduated to at least 30 PSIG.
(b) The gage shall have effective stops for the indicating pointer at the:
(i) Zero point; and
(ii) Maximum pressure point.
(c) The travel of the pointer from zero to 30 PSIG shall be at least 3 inches.
D. Stop Valve and Check Valve.
(1) A boiler which can be closed off from the heating system by closing a steam stop valve shall have a check valve in the condensate return line between the boiler and the system.
(2) Any part of a heating system that can be closed off from the remainder of the system by closing a steam stop valve shall have a check valve in the condensate return pipe from that part of the system.
E. A hot water boiler shall have a thermometer located and connected so that:
(1) A person observing the water pressure or altitude gage can read the thermometer easily; and
(2) The thermometer at all times indicates the temperature, in degrees Fahrenheit, of the water in the boiler at or near the outlet.
F. Water Gage Glass.
(1) A steam boiler shall have at least one water gage glass attached to the water column or boiler by valved fittings.
(2) The lower fitting shall have a straightway drain valve with an opening at least 1/4 inch diameter to facilitate cleaning.
(3) Gage glass replacement shall be possible while the boiler is under pressure.
(4) Transparent material other than glass may be used for a water gage if the material is suitable for the pressure, temperature, and corrosive conditions encountered in service.
G. When practicable, a boiler equipped with a condensate return pump shall have a water level control that automatically maintains the water level in the boiler within the range of the gage glass.
H. Repairs and replacements of fittings or appliances shall comply with the ASME Code for new construction, Section IV.
I. The ASME Code, Section VI, Recommended Rules for the Care and Operation of Heating Boilers is recommended as a guide for proper and safe operating practices.
J. It is recommended that a return water connection to a low-pressure steam heating boiler supplying a gravity return heating system be arranged to form a return pipe loop connection, so that water cannot be forced out of the boiler below the safe water level, as shown in Section IV, Figure HG-703.1 of the ASME Heating Boiler Code.(Regulations .12 adopted effective June 1, 1989 (16:10 Md. R. 1106))