Document RBwn031Gxn2okbj6DgwjYK3X

440 CHAPTER 17 1956 Guide of Fire Underwriters, Article X, Section 1001 to 1006, in which the following are some of the important provisions listed in the 1951 edition: 1. Flue Connections Required. Every heating apparatus pr heat producing ap pliance requiring a flue connection shall be connected with a flue conforming to the provisions of this article. This shall not include electric appliances; gas appliances, except as specifically required in this article; or oil fired appliances especially de signed for use without flue connection. 2. Use of Nonconforming Flues. Flues not conforming to the requirements of this article for chimneys, metal smokestacks or vents for gas appliances, shall not be used unless listed by Underwriters' Laboratories, Inc., installed in full compliance with the listing and the manufacturer's instructions, and approved for such use by the building official. 3. Smoke Pipe Connections. a. No flue shall have smoke pipe connections in more than one story of a building, unless provision is made for effectively closing smoke pipe openings with devices made of noncombustible materials whenever their use is discontinued temporarily, and. completely closing them with masonry when discontinued permanently. b. Two or more smoke pipes shall not be joined for a single connection, unless the smoke pipes and flue are of sufficient size to serve all the appliances thus con nected. c. The smoke pipe of a heating appliance shall not be connected into the flue of an incinerator which has the rubbish chute identical with the smoke flue. 4. Construction of Chimneys. a. Chimneys hereafter erected within or attached to a structure shall be con structed in compliance with the provisions of this section. b. Chimneys shall extend at least 3 ft above the highest point where they pass through the roof of the building, and at least 2 ft higher than any ridge within 10 ft of such chimney. c. Chimneys shall be wholly supported on masonry or self-supporting fireproof construction. d. No chimney shall be corbeled from a wall more than 6 in.; nor shall a chimney be corbeled from a wall which is less than 12 in. in thickness, unless it projects equally on each side of the wall; provided that in the second story of 2-story dwellings cor beling of chimneys on the exterior of the enclosing walls may equal the wall thickness. In every case the corbeling shall not exceed 1 in. projection for each course of brick projected. e. No change in the size or shape of a chimney, where the chimney passes through the roof, shall be made within a distance of 6 in. above or below the roof joists or rafters. 5. Chimneys for Healing Appliances, Low Heat Industrial Appliances and Portable Type Incinerators. a. Chimneys for stoves, cooking ranges, warm air, hot water and low pressure steam heating furnaces, fireplaces, and low heat industrial appliances, other than chimneys for incinerators of nonportable type, shall be constructed of solid masonry units or of reinforced concrete. The walls shall be properly bonded or tied with corrosion-resistant metal anchors. In dwellings and buildings of like heating re quirements, the thickness of the chimney shall be not less than 4 in. In other build ings the thickness shall be not less than 8 in., except that rubble stone masonry shall be not less than 12 in. thick. b. Every such chimney hereafter erected or altered shall be lined with a flue lin ing conforming to the requirements below. c. Flue linings shall be made of fire clay or other refractory clay which will with stand the action of flue gases and resist, without softening or cracking, the tempera tures to which they will be subjected, but not less than 2000 F. Flue linings may be of cast iron of approved quality, form and construction. d. Required clay flue linings Bhall be not less than f in. thick for the smaller flues, and shall increase in thickness for the larger flues. e. Flue linings shall be installed ahead of the construction of the chimney as it is i Chimneys and Draft Calculations 44.1 carried up, carefully bedded one on the other in Type A, Type B, or fire clay mortar with close fitting joints left smooth on the inside. f. Flue linings shall start from a point not less than 8 in. below the intake, or, in the case of fireplaces, from the throat of the fireplace. They shall extend, as nearly vertically as possible, for the entire height of the chimney, and be extended 4 in. above the top of cap of the chimney. g. Cleanouts for flues or fireplaces shall be equipped with cast-iron doors and frames arranged to remain tightly closed when not in use. h. When two or more flues are contained in the same chimney, at least every third flue shall be separated by masonry at least 4 in. thick bonded into the masonry wall of the chimney. Where flue linings are not so separated, the joints of adjacent flue linings shall be staggered at least 7 in. 6. Sizes of Flues. a. The cross-sectional area of smoke flues shall be designed and proportioned to Table 4. Results op Field Survey on Chimney Damage orType Construction Number op Chimneys Number Reported Damaqed . Percent Damaged Chimneys without liners................................ Chimneys with sewer tile construction........ Wilder metal coated with asphalt chromate emulsion........................................................ Steel coated with plastic................................ Vitreous enamel on steel................................ Aluminum.......................................... ..... 4720 8410 5185 9200 614 50,000 562 104 291 1928 No record 228 11.9 1.2 ,5.6 21.0 -- 0.45 meet the conditions of temperature, within and without flue, thickness of masonry, exposure, shape and material of flue, and other influences. The National Building Code specifies lined chimneys and metal smoke stacks for all gas appliances which may be converted readily to the use of solid or liquid fuel, and also for all boilers and furnaces, except those having a flue-gas temperature not exceeding 550 F at the outlet of the draft hood when burning gas at the manufacturer's rating and which may, therefore, be connected to Type B vent piping. Approved Type B vent piping is noncombustible, corrosion-resistant piping of adequate strength and heat-insulating value, and having bell and spigot or other acceptable joints. Fig. 10 may be used for selection of vent-pipe size. Important points to be considered in the use of Type B vent piping are: 1. Type B flues must be plainly and permanently marked at the point where the vent connection enters the flue: For Use of Gas Appliances Only. 2. Type B gas vents shall be.installed with a clearance to combustible material or construction, whether plastered or unplastered, of not less than one inch, provided that for vents of floor furnaces, such clearance shall be not less than 3 ft from the outlet of the draft hood, measured along the center line of the vent piping. Other important points that should be considered for flues and vents for gas appliances are as follows: 1. Clearances from combustible material to gas appliance vent piping other than approved Type B gas vents shall be in accordance with the Building Code Standards