CHAPTER 91
GENERAL REQUIREMENTS FOR ALL OBJECTS
[Prior to 1/14/98, see 347—Chs 41 to 49]
[Prior to 8/16/06, see 875—Ch 203]
875—91.1(89) Codes and code cases adopted by reference.
	91.1(1) ASME boiler and pressure vessel codes adopted by reference. The ASME Boiler and Pressure Vessel Code (2021) is adopted by reference. Regulated objects shall be designed and constructed in accordance with the ASME Boiler and Pressure Vessel Code (2021) except for objects that meet one of the following criteria:
	a. 	An object with an ASME stamp and National Board Registration that establish compliance with an earlier version of the ASME Boiler and Pressure Vessel Code;
	b. 	A miniature boiler installed before March 31, 1967;
	c. 	A power boiler or unfired steam pressure vessel installed before July 4, 1951; or
	d. 	A steam heating boiler, hot water heating boiler, or hot water supply boiler installed before July 1, 1960.
	91.1(2) ASME code cases. If the manufacturer of an object listed ASME Code Case 2668-1, 2760, 2764-1, or 2869 on the manufacturer’s data report for the object and the object is otherwise in compliance with all applicable provisions, the object is in compliance with these rules.
	91.1(3) Inspection code adopted by reference. The National Board Inspection Code (2021) is adopted by reference, and installations, alterations, and repairs after February 16, 2022, shall comply with it.
	91.1(4) Electric code adopted by reference. The National Electrical Code, NFPA 70 (2020), is adopted by reference, and installations after April 15, 2020, shall comply with it.
	91.1(5) Piping codes adopted by reference. The Power Piping Code, ASME B31.1 (2020), and the Building Services Piping Code, ASME B31.9 (2020), are adopted by reference, and installations after February 16, 2022, shall comply with them up to and including the first valve.
	91.1(6) Control and safety device code adopted by reference. Controls and Safety Devices for Automatically Fired Boilers (CSD-1) (2018) is adopted by reference, and installations after April 15, 2020, shall comply with it. Reporting requirements concerning CSD-1 are set forth at rule 875—90.11(89).
	91.1(7) Mechanical code adopted by reference. Excluding Section 701.1, Chapters 2 and 7 of the International Mechanical Code (IMC) (2021) are adopted by reference, and installations after February 16, 2022, shall comply with them.
	91.1(8) Oil burning equipment code adopted by reference. National Fire Protection Association Standard for the Installation of Oil Burning Equipment, NFPA 31 (2020), is adopted by reference, and installations after February 16, 2022, shall comply with it.
	91.1(9) Fuel gas code adopted by reference. National Fire Protection Association National Fuel Gas Code, NFPA 54 (2021), is adopted by reference, and installations after February 16, 2022, shall comply with it.
	91.1(10) Liquefied petroleum gas code adopted by reference. National Fire Protection Association Liquefied Petroleum Gas Code, NFPA 58 (2020), is adopted by reference, and installations after April 15, 2020, shall comply with it.
	91.1(11) Boiler and combustion systems hazards code adopted by reference. National Fire Protection Association Boiler and Combustion Systems Hazards Code, NFPA 85 (2019), is adopted by reference, and installations after April 15, 2020, shall comply with it.
[ARC 8283B, IAB 11/18/09, effective 1/1/10; ARC 8590B, IAB 3/10/10, effective 4/14/10; ARC 9232B, IAB 11/17/10, effective 12/22/10; ARC 9790B, IAB 10/5/11, effective 11/9/11; ARC 0319C, IAB 9/5/12, effective 10/10/12; ARC 0416C, IAB 10/31/12, effective 12/5/12; ARC 1011C, IAB 9/18/13, effective 10/31/13; ARC 1964C, IAB 4/15/15, effective 5/20/15; ARC 2403C, IAB 2/17/16, effective 4/1/16; ARC 2589C, IAB 6/22/16, effective 7/27/16; ARC 3635C, IAB 2/14/18, effective 3/21/18; ARC 3903C, IAB 7/18/18, effective 9/1/18; ARC 4303C, IAB 2/13/19, effective 3/20/19; ARC 4977C, IAB 3/11/20, effective 4/15/20; ARC 5977C, IAB 10/20/21, effective 11/24/21; ARC 6135C, IAB 1/12/22, effective 2/16/22]
875—91.2(89) Safety appliance.
	91.2(1) No person shall remove, disable or tamper with a required safety appliance except for the purpose of repair or inspection.
	91.2(2) An object shall not be operated unless all required and installed safety appliances are properly functional and operational.
[ARC 5977C, IAB 10/20/21, effective 11/24/21]
875—91.3(89) Pressure-reducing valves. Rescinded ARC 3903C, IAB 7/18/18, effective 9/1/18.
875—91.4(89) Blowoff equipment. The blowdown from an object that enters a sanitary sewer system or blowdown that is considered a hazard to life or property shall pass through blowoff equipment that will reduce pressure and temperature. The temperature of the water leaving the blowoff equipment shall not exceed 150 degrees Fahrenheit. If the local jurisdiction has a temperature limit of less than 150 degrees Fahrenheit, the temperature of the water leaving the blowoff equipment shall comply with the limit set by the local jurisdiction. The pressure of the water leaving the blowoff equipment shall not exceed 5 psig. The blowoff piping and fittings between the object and the blowoff tank shall comply with the construction or installation code. All materials used in the fabrication of object blowoff equipment shall comply with the construction or installation code. All blowoff equipment shall be equipped with openings to facilitate cleaning and inspection.
[ARC 8283B, IAB 11/18/09, effective 1/1/10]
875—91.5(89) Location of discharge piping outlets. The discharge from safety valves, safety relief valves, blowoff pipes and other outlets shall comply with the following:
	91.5(1) The discharge piping shall terminate at a safe point of discharge.
	91.5(2) When the safety valve or temperature and pressure relief valve discharge is piped away from the object to a safe point of discharge, provision shall be made for properly draining the piping.
	91.5(3) The size of the discharge piping shall not be reduced from the size of the relief valve.
	91.5(4) All discharge piping shall be comprised of appropriate metallic material identified in ASME Section II.
[ARC 5977C, IAB 10/20/21, effective 11/24/21]
875—91.6(89) Pipe, valve, and fitting requirements. Pipes, valves, and fittings subject to the effects of galvanic action shall not be used on objects covered by these rules. Dielectric fittings shall be used where dissimilar metals are joined.
[ARC 8283B, IAB 11/18/09, effective 1/1/10; ARC 3903C, IAB 7/18/18, effective 9/1/18]
875—91.7(89) Repairs and alterations to unfired steam pressure vessels. No single repair of an unfired steam pressure vessel shall involve replacement of more than 50 percent of the OEM’s pressure-retaining boundary.
[ARC 5977C, IAB 10/20/21, effective 11/24/21]
875—91.8(89) Plugging boiler tubes. This rule does not apply to tubes in headers of economizers, evaporators, superheaters, or reheaters.
	91.8(1) General requirements.
	a. 	Leaky tubes shall be replaced or plugged.
	b. 	Tube plugs shall be made of a material which is compatible with the material of the boiler tube being plugged and shall be welded into place or manufactured to be expanded into the tube sheet or drum.
	c. 	All plugged boiler tubes shall be replaced prior to the next required certificate inspection.
	d. 	The maximum number of tubes that shall be plugged is the lesser of the number specified by the OEM or the number specified by an engineer experienced in boiler design. Documentation of the maximum number of tubes that may be plugged as determined by the OEM or engineer shall be kept on site, and a copy shall be mailed to the division of labor services.
	91.8(2) Fire tube boilers. In a fire tube boiler, a tube that is adjacent to a plugged tube shall not be plugged.
	91.8(3) Water tube boilers, unfired boilers, or process steam generators. To determine the maximum number of tubes that may be plugged in a water tube boiler, unfired boiler, or process steam generator, an engineer experienced in boiler design shall consider the operational effect on the water side pressure boundary or membrane and the effect on the combustion process throughout the boiler. Water wall tubes may not be plugged if the tubes form a separation wall between products of combustion and the outside atmosphere or a separation of the gas passes in a multiple gas pass boiler.
[ARC 5977C, IAB 10/20/21, effective 11/24/21]
875—91.9(89) Boiler door latches. Rescinded ARC 0319C, IAB 9/5/12, effective 10/10/12.
875—91.10(89) Equipment room. This rule applies to existing and new installations except as noted in subrule 91.10(1).
	91.10(1) Clearances.
	a. 	All objects installed after December 1, 2021, shall be installed with the clearances identified in NBIC Part 1.
	b. 	This paragraph applies to objects installed after September 20, 2006, and before December 1, 2021. Minimum clearance on all sides of objects shall be 24 inches, or the manufacturer’s recommended service clearances if they allow sufficient room for inspection. Where a manufacturer identifies in the installation manual or other document that the unit requires more than 24 inches of service clearance, those dimensions shall be followed. Manholes shall have five feet of clearance between the manhole opening and any wall, ceiling or piping that would hinder entrance or egress from the object.
	c. 	All objects installed prior to September 20, 2006, shall be so located that adequate space is provided for the proper operation, inspection, and necessary maintenance and repair of the object and its appurtenances.
	91.10(2) Condition of the equipment room.
	a. 	The roof, walls and floor of the equipment room shall be free from leaks and structurally sound.
	b. 	The equipment room shall have drainage adequate to remove standing water from the floor.
	c. 	The equipment room shall be free from materials that obstruct access to the objects, their setting, or operation.
	d. 	Storage of flammable material or gasoline-powered equipment in the equipment room is prohibited.
	91.10(3) Exit from equipment room. This subrule shall apply to an equipment room exceeding 500 square feet of floor area, containing at least one object, and containing fuel-burning equipment with at least a combined capacity of 1,000,000 Btu per hour or the equivalent electrical heat input. Two means of exit located remotely from one another shall be provided on each elevation for covered equipment rooms. A platform at the top of a single object or other equipment is not considered an elevation.
	91.10(4) Carbon monoxide detector or alarm. The owner or user shall install a carbon monoxide detector or alarm in an equipment room where one or more fuel-fired objects are located.
	a. 	The carbon monoxide detector or alarm shall have a visible display showing the parts per million value of the carbon monoxide that is detected.
	b. 	The carbon monoxide detector or alarm shall be hardwired to the building power and shall have a battery backup with visible and audible alarms that identify when the battery backup power supply is low.
	c. 	The carbon monoxide detector or alarm shall be tested daily and shall be calibrated in accordance with the manufacturer’s recommendations, or every 18 months after installation of the detector. The testing and calibration shall be recorded in a log book that is readily accessible to the inspectors and owner’s staff.
	d. 	The carbon monoxide detector or alarm shall have visible and audible alarms capable of being heard and seen both inside and outside of the equipment room.
[ARC 5977C, IAB 10/20/21, effective 11/24/21]
875—91.11(89) Fall protection. The owner or user shall provide safe access to object parts over four feet high consistent with 29 CFR Subpart D, Walking-Working Surfaces, and 29 CFR 1910.140, Personal Fall Protection Systems.
[ARC 5977C, IAB 10/20/21, effective 11/24/21]
875—91.12(89) Exit from rooms containing objects. Rescinded ARC 5977C, IAB 10/20/21, effective 11/24/21.
875—91.13(89) Air and ventilation.
	91.13(1) Notice concerning other rules. The division and the Iowa department of public safety both enforce requirements concerning air and ventilation. Objects that are covered by both sets of rules must comply with both sets of rules.
	91.13(2) Documentation. Documentation of compliance with any requirement of this rule shall be maintained in the boiler room. However, it is not necessary to maintain documentation of the louvered area.
	91.13(3) National combustion air standards.
	a. 	Installations. Installations shall comply with the edition of NFPA 31, NFPA 54, NFPA 58, NFPA 85, or IMC currently adopted at rule 875—91.1(89) or with the Iowa combustion air standard in subrule 91.13(4). However, compliance with one of the listed NFPA codes constitutes compliance with this rule only if the object burns the fuel covered by the NFPA.
	b. 	Existing objects. An adequate supply of combustion air shall be maintained for all objects while in operation. Compliance with the current edition of NFPA 31, NFPA 54, NFPA 58, NFPA 85, or IMC as adopted at rule 875—91.1(89) or with subrule 91.13(4) constitutes compliance with this rule. Compliance with an earlier edition of NFPA 31, NFPA 54, NFPA 58, NFPA 85, or IMC constitutes compliance with this rule. However, compliance with one of the listed NFPA codes constitutes compliance with this rule only if the object burns the fuel covered by the NFPA. Compliance with an earlier version of Iowa’s combustion air rule constitutes compliance with this rule. Earlier versions of Iowa’s combustion air rule are available from the board’s staff upon request.
	91.13(4) Iowa combustion air standard. A permanent source of outside air shall be provided for each room to permit satisfactory combustion of fuel and ventilation if necessary under normal operations. The minimum ventilation for coal, gas, or oil burners in rooms containing objects is based on the Btu’s per hour, required air, and louvered area. The minimum net louvered area shall not be less than 1 square foot. The following table shall be used to determine the net louvered area in square feet:

INPUT
(Btu’s per hour)	MINIMUM AIR REQUIRED
(cubic feet per minute)	MINIMUM LOUVERED AREA
(net square feet)	
500,000	125	1.0	
1,000,000	250	1.0	
2,000,000	500	1.6	
3,000,000	750	2.5	
4,000,000	1,000	3.3	

5,000,000	1,200	4.1	
6,000,000	1,500	5.0	
7,000,000	1,750	5.8	
8,000,000	2,000	6.6	
9,000,000	2,250	7.5	
10,000,000	2,500	8.3	
When mechanical ventilation is used, the supply of combustion and ventilation air to the objects and the firing device shall be interlocked with the fan so the firing device will not operate with the fan off. The velocity of the air through the ventilating fan shall not exceed 500 feet per minute, and the total air delivered shall be equal to or greater than shown above.
[ARC 8283B, IAB 11/18/09, effective 1/1/10; ARC 3635C, IAB 2/14/18, effective 3/21/18; ARC 5977C, IAB 10/20/21, effective 11/24/21]
875—91.14(89) Condensate return tank. Condensate return tanks shall be equipped with at least two vents or a vent and overflow pipe to protect against a loose float plugging a single connection.
875—91.15(89) Conditions not covered. Any condition not governed by these rules shall be governed by the construction or installation code.
875—91.16(89) Nonstandard objects. Rescinded IAB 3/12/08, effective 4/16/08.
875—91.17(89) English language and U.S. customary units required. All documentation supplied for the unit including but not limited to the manufacturers’ data report, drawings, parts lists, installation manuals, and operating manuals shall be in English, and all measurements shall be in U.S. customary units. All pressure gages, thermometers and other controls and safety devices shall also be in U.S. customary units.
875—91.18(89) National Board registration. Except for cast iron boilers and cast aluminum boilers, all objects shall be registered with the National Board.
[ARC 8283B, IAB 11/18/09, effective 1/1/10; ARC 3903C, IAB 7/18/18, effective 9/1/18]
875—91.19(89) ASME stamp.  All objects shall bear the appropriate ASME stamp. Objects shall not be utilized in a manner inconsistent with the stamp.
[ARC 8283B, IAB 11/18/09, effective 1/1/10; ARC 3903C, IAB 7/18/18, effective 9/1/18]
875—91.20(89) CSD-1 reports and related documentation. Rescinded ARC 2589C, IAB 6/22/16, effective 7/27/16.
These rules are intended to implement Iowa Code chapter 89.
[Filed emergency 12/26/97 after Notice 11/19/97—published 1/14/98, effective 1/1/98]
[Filed 3/14/01, Notice 1/24/01—published 4/4/01, effective 5/9/01]
[Filed 7/26/06, Notice 5/10/06—published 8/16/06, effective 9/20/06]
[Filed 6/27/07, Notice 5/9/07—published 7/18/07, effective 8/22/07]
[Filed 11/30/07, Notice 10/24/07—published 12/19/07, effective 1/23/08]
[Filed 2/19/08, Notice 12/19/07—published 3/12/08, effective 4/16/08]
[Filed 6/24/08, Notice 5/7/08—published 7/16/08, effective 8/20/08]
[Filed ARC 8283B (Notice ARC 8082B, IAB 8/26/09), IAB 11/18/09, effective 1/1/10]
[Filed ARC 8590B (Notice ARC 8391B, IAB 12/16/09), IAB 3/10/10, effective 4/14/10]
[Filed ARC 9232B (Notice ARC 9087B, IAB 9/22/10), IAB 11/17/10, effective 12/22/10]
[Filed ARC 9790B (Notice ARC 9511B, IAB 5/18/11), IAB 10/5/11, effective 11/9/11]
[Filed ARC 0319C (Notice ARC 0207C, IAB 7/11/12), IAB 9/5/12, effective 10/10/12]
[Filed ARC 0416C (Notice ARC 0322C, IAB 9/5/12), IAB 10/31/12, effective 12/5/12]
[Filed ARC 1011C (Notice ARC 0817C, IAB 7/10/13), IAB 9/18/13, effective 10/31/13]
[Filed ARC 1964C (Notice ARC 1798C, IAB 12/24/14), IAB 4/15/15, effective 5/20/15]
[Filed ARC 2403C (Notice ARC 2251C, IAB 11/25/15), IAB 2/17/16, effective 4/1/16]
[Filed ARC 2589C (Notice ARC 2419C, IAB 2/17/16), IAB 6/22/16, effective 7/27/16]
[Filed ARC 3635C (Notice ARC 3504C, IAB 12/20/17), IAB 2/14/18, effective 3/21/18]
[Filed ARC 3903C (Notice ARC 3807C, IAB 5/23/18), IAB 7/18/18, effective 9/1/18]
[Filed ARC 4303C (Notice ARC 4179C, IAB 12/19/18), IAB 2/13/19, effective 3/20/19]
[Filed ARC 4977C (Notice ARC 4863C, IAB 1/15/20), IAB 3/11/20, effective 4/15/20]
[Filed ARC 5977C (Notice ARC 5806C, IAB 7/28/21), IAB 10/20/21, effective 11/24/21]
[Filed ARC 6135C (Notice ARC 5979C, IAB 10/20/21), IAB 1/12/22, effective 2/16/22]