Missouri Code of State Regulations
Title 11 - DEPARTMENT OF PUBLIC SAFETY
Division 40 - Division of Fire Safety
Chapter 2 - Boiler and Pressure Vessel Safety Rules
Section 11 CSR 40-2.040 - Heating Boiler

Universal Citation: 11 MO Code of State Regs 40-2.040

Current through Register Vol. 49, No. 6, March 15, 2024

PURPOSE: This rule is to address the design, construction, installation, and operation of heating boilers, water heaters, and jacketed steam kettles.

(1) As used in this rule, the term "these rules" is intended to mean 11 CSR 40-2.010 through 11 CSR 40-2.065.

(2) Heating Boilers, Water Heaters, Pool Heaters, and Fired Jacketed Steam Kettles, Installed or Contracted for Prior to November 12, 1986.

(A) The service life of any boiler, water heater, pool heater, or fired jacketed steam kettle of standard construction shall be unlimited, provided:
1. It meets the inspection requirements of 11 CSR 40-2.022; and

2. All controls and safety devices required by American Society of Mechanical Engineers (ASME) Section IV Code for heating boilers and water heaters and ASME Section VIII, Division 1 Code for fired jacketed steam kettles and these rules shall be installed and operable.

(B) The service life of any heating boiler, water heater, pool heater, or fired jacketed steam kettle of nonstandard construction shall be thirty (30) years. The thirty (30)-year life may be extended with the chief inspector's approval and compliance with the following requirements:
1. The operating pressure cannot exceed the maximum allowable working pressure (MAWP). The boiler, water heater, or fired jacketed steam kettle MAWP shall be calculated in accordance with the ASME Code or the requirements of the original code of construction. Objects manufactured to a standard other than the ASME Code shall be evaluated in accordance with the "state special" requirements in accordance with 11 CSR 402.064. The allowable stress shall be no greater than eleven thousand pounds per square inch (11,000 psi). The joint efficiency shall be in accordance with the appropriate edition and addenda of the ASME Code, most applicable for the type of construction. The MAWP of any cast iron boiler shall not be greater than fifteen (15) psi steam or thirty (30) psi water pressure;

2. A pressure test shall be conducted every four (4) years at normal operating pressure not to exceed the MAWP of the object. The test pressure shall be held for at least thirty (30) minutes without evidence of leakage and documented to the satisfaction of the inspector. The inspector need not witness the test. The test may be an operational test. If the object exhibits any signs of leakage, it shall be repaired prior to restoring the object to service;

3. All safety devices and controls required by the applicable ASME Code and these rules shall be installed and operable.

(3) Heating Boilers, Water Heaters, Pool Heaters, and Fired Jacketed Steam Kettles Contracted after November 12, 1986.

(A) New and second-hand heating boilers, water heaters, and pool heaters shall be designed, fabricated, and installed to the requirements of ASME Section IV Code and these rules. New and second-hand fired jacketed steam kettles shall be designed, fabricated, and installed to the requirements of ASME Section VIII, Division 1 Code and these rules.

(B) Reinstalled boilers may be of standard or nonstandard construction and shall be installed in accordance with the requirements of the ASME Code and these rules, non-standard heating boilers cannot be reinstalled in Missouri except when relocating from one location to another location within Missouri. Approval of the chief inspector shall be obtained prior to reinstalling a nonstandard boiler.

(4) General Requirements for Heating Boilers, Water Heaters, Pool Heaters, and Fired Jacketed Steam Kettles.

(A) Heating boilers, water heaters, pool heaters, and fired jacketed steam kettles shall not be operated for a purpose not originally intended by the manufacturer unless approved by the board (i.e., potable water heaters may not be operated as a steam or hot water heating boiler).

(B) Heating boilers, water heaters, pool heaters, and fired jacketed steam kettles must be installed in accordance with the manufacturer's instructions and these rules, unless otherwise approved by the chief inspector.

(C) Heating boilers with heat input less than 12,500,000 British thermal units per hour (Btu/hr) contracted after January 1, 2004, shall meet the requirements of ASME CSD-1. Fuel gas piping for these boilers shall comply with the requirements of National Fire Protection Association (NFPA) 54. Oil burning equipment shall comply with the requirements of NFPA 31. Single unit boilers with heat input greater than or equal to 12,500,000 Btu/hr, boilers with pulverized fuel systems, and waste heat boilers shall meet the requirements of NFPA 85. All controls required by NFPA 85 for automatically fired boilers shall be installed in accordance with the installation requirements of ASME CSD-1. Existing installations are exempt from these rules except that any modification or replacements to the controls after January 1, 2004, shall meet the requirements for new installations. Boilers installed on or after January 1, 2010, must be in accordance with the National Board Inspection Code, Part 1, and these rules.

(D) All safety and safety relief valve outlets shall be piped to a safe discharge. There shall be no valves on the outlet piping or between the boiler and the safety or safety relief valve inlet. The end of all discharge piping shall be visible to the operator when piped into a drain. Drains on safety or safety relief valve bodies shall remain open at all times. Safety or safety relief valve inlet and outlets shall not be reduced. Weighted lever safety valves are prohibited. Safety valves with either the seat or disk of cast iron are prohibited. The minimum valve capacity shall be in accordance with ASME Section IV Code for heating boilers and hot water heaters and Appendix 19 of ASME Section VIII, Division 1 Code for fired jacketed steam kettles. Alternatively, the relieving capacity for heating boilers may be determined based on the burner output rating or by multiplying the heating surface in square feet by the applicable value in the following table:

Minimum Pounds of Steam Per Hour Per Square Foot of Heating Surface

Fire Tube Boiler Water Tube Boiler
Boiler
Hand fired 5 6
Stoker fired 7 9
Oil, gas, pulverized fuel fired 8 10
Waterwall
Hand fired 8 8
Stoker fired 10 10
Oil, gas, pulverized fuel fired 14 16

When a boiler is fired only by a gas having a heat value not in excess of two hundred (200) Btu/cubic feet (cu. ft.), the minimum safety or safety relief valve capacity may be based on the value given for hand fired boilers. The minimum safety or safety relief valve capacity for electric boilers shall be three and one-half (3.5) pounds per hour per kilowatt input.

(E) Each heating boiler, water heater, and fired jacketed steam kettle shall be safely supported. There shall be no excessive vibration in either the object or the connecting piping.

(F) All existing heating boilers, water heaters, pool heaters, and fired jacketed steam kettles shall have adequate clearance on all sides and top to facilitate repair, maintenance, and inspection. Heating boilers, water heaters, pool heaters, and fired jacketed steam kettles, installed or reinstalled on or after January 1, 2010, shall meet the following requirements:
1. There shall be at least thirty-six inches (36") of clearance on each side of the boiler. Boilers in battery shall not be installed any closer than forty-eight inches (48"). The front and rear of the boiler shall not be located nearer than thirty-six inches (36") from any wall or structure;

2. Boilers shall be installed to allow for removal and installation of tubes;

3. Boilers with top-opening manholes shall have at least eighty-four inches (84") of unobstructed clearance above the manhole to the ceiling of the boiler room;

4. Boilers without top-opening manholes shall have at least thirty-six inches (36") clearance from the top of the boiler;

5. Boilers with bottom openings used for inspection or maintenance shall have at least twelve inches (12") of unobstructed clearance; and

6. Modular heating boilers that require individual units to be set side by side, front to back, or by stacking may provide clearances in accordance with the manufacturer's recommendations with the approval of the chief inspector.

7. Note: Alternatively, clearances in accordance with the manufacturer's recommendations are subject to the approval of the chief inspector.

(G) All rooms containing heating boilers, water heaters, and fired jacketed steam kettles with a combined capacity over one (1) million Btu/hr and over five hundred (500) square feet floor area shall have at least two (2) exits remotely located from each other.

(H) Ladders and runways shall be provided between or over the top of boilers installed or reinstalled on or after January 1, 2010, that are more than eight feet (8') above the operating floor to afford accessibility for normal operation, maintenance, and inspection. These ladders and runways must be built and installed in accordance with the National Board Inspection Code, Part 1.

(I) Combustion air-The boiler room shall have an adequate air supply to permit clean, safe combustion, minimize soot formation, and maintain a minimum of nineteen and one-half percent (19.5%) oxygen in the air of the boiler room. The combustion and ventilation air shall be supplied by an unobstructed opening or by power ventilation or fans.
1. Unobstructed air openings shall be sized on the basis of one (1) sq. in. (6.50 sq. mm) free area per two thousand British thermal units per hour (2,000 Btu/hr) (five hundred eighty-six watts per hour (586 W/hr)) maximum fuel input of the combined burners located in the boiler room or as specified in the National Fire Protection Association (NFPA) standards for oil and gas burning installations for the particular job conditions. The boiler room air supply openings shall be kept clear at all times.

2. Power ventilators or fans shall be sized on the basis of 0.2 cfm (.0057 cubic meters per minute) for each one thousand British units per hour (1,000 Btu/hr) (two hundred ninety-three watts per hour (293 W/hr)) of maximum fuel input for the combination burners of all boilers located in the boiler room. Additional capacity shall be required for any other fuel burning equipment in the boiler room.

3. When power ventilators or fans are used to supply combustion air, they shall be installed with interlock devices so that the burners will not operate without an adequate number of ventilators/fans in operation.

4. When combustion air is supplied to the boiler by an independent duct, with or without the employment of power ventilators or fans, the duct shall be sized and installed in accordance with the manufacturer's recommendations. However, ventilation of the boiler room must still be considered.

5. Care should be taken to ensure that steam and water lines are not routed across combustion air openings, where freezing may occur.

6. Opening boiler room door(s) and/or window(s) is unacceptable for supplying combustion air.

(J) Controls-
1. Oil-fired, gas-fired, and electrically heated heating boilers, water heaters, pool heaters, and fired jacketed steam kettles shall be equipped with suitable primary (flame safeguard) safety controls, limit switches, and burners or electric elements that are labeled and listed by a nationally or internationally recognized standard.

2. All controls and devices shall be installed in accordance with the manufacturer's recommendations, and/or industry standards, as applicable.

3. All automatically fired heating boilers, water heaters, pool heaters, and fired jacketed steam kettles shall have a disconnecting means capable of being locked in the open position and shall be installed at an accessible location in the same room as the object. This disconnect means shall disconnect all sources of potential from the object.

4. A manually operated remote shutdown switch or circuit breaker shall be located just outside the entrance door of the room the object is located in and be marked for easy identification. Consideration should be given to the type and location of the switch to safeguard against tampering. If the entrance door is on the building exterior, the switch should be located just inside the door. If there is more than one (1) door to the room, there should be a switch located at each door. The emergency switch must be installed in accordance with the manufacturer's instructions or a nationally recognized standard and must cause a safety shutdown and lockout.

(K) Each gas-fired water heater contracted after January 1, 2010, must be certified to the American National Standard/CSA Standard for Gas Water Heaters, Volume III (ANSI Z21.10.3 CSA 4.3) and must bear a label as proof of this certification.

(L) Each gas-fired pool heater contracted after January 1, 2010, must meet one (1) of the following-
1. Be certified to the American National Standard/CSA Standard For Gas-Fired Pool Heaters, (ANSI Z21.56 CSA 4.7) and bear the label as proof of this certification; or

2. Commercial pool heaters applications that do not have one hundred percent (100%) of pool loop water flow circulating through the pool heater may be certified to the American National Standard/CSA Standard for Gas Water Heaters, Volume III (ANSI Z21.10.3 CSA 4.3) and must bear a label as proof of this certification, provided the unit must bear a label from the manufacturer as evidence that the water heater has been approved for commercial pool heating applications when installed per the manufacturer's instructions. Additionally, the manufacturer must provide additional listed temperature controls that will limit the water temperature delivered to the pool from exceeding one hundred eight degrees Fahrenheit (108 oF) with details for the installation of these controls.

(M) The Code nameplates shall remain readily accessible at all times. Loose or missing nameplates shall be replaced or reattached as provided for in the National Board Inspection Code.

(N) Rental heating boilers, water heaters, and fired jacketed steam kettles, used for temporary service, shall meet all of the requirements of these rules. The internal inspection, required by 11 CSR 40-2.022, may be waived by the inspector, based on documentation that a national board-commissioned inspector has evaluated the internal surfaces of the object within the past twelve (12) months and found the object acceptable for use. An external, in-operation inspection shall be the basis for the inspection certificate. The inspection certificate shall expire no later than twenty-four (24) months from the date of the last internal inspection.

*Original authority: 650.215, RSMo 1984, amended 1990, 1993, 1995.

Disclaimer: These regulations may not be the most recent version. Missouri may have more current or accurate information. We make no warranties or guarantees about the accuracy, completeness, or adequacy of the information contained on this site or the information linked to on the state site. Please check official sources.
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