CSA ANSI Z21.42-13:2018 pdf download.Gas-fired illuminating appliances
4.1.2 Every part of an appliance shall be designed to be secure against displacement and constructed to maintain a fixed relationship between essential parts under normal and reasonable conditions of handling and usage.
Parts not permanently secured shall be designed so that they cannot be incorrectly assembled or improperly located when removed and replaced during cleaning or other servicing.
In submitting and appliance for test, the manufacturer may furnish a list of manufacturing tolerances applicable thereto and may have the appliance tested for compliance with this standard in both extremes of tolerances specified.
4.1.3 Exposed edges which might reasonably be brought in contact with the hand during normal adjustment or usage shall have no sharp edges or points.
4.1.5 Bolts, nuts, and screws employed in the assembly of an iluminating appliance shall not require the use of special tools for removal or replacement. (See definition of tools, special, in Clause 3, Definitions.)
4.1.6 Slotted and recessed head screws used in the general assembly of an illuminating appliance shall conform to the Standard for Slotted Head Cap Screws, Square Head Set Screws and Slotted Head-less Set Screws, ANSI B18.6.2, the Standard for Slotted and Recessed Head, Machine Screws and Machine Screw Nuts, ANSI B18.6.3, or the Standard for Thread Forming and Thread Cutting Tapping Screws and Metallic Drive Screws (Inch Series), ANSI B18.6.4.
4.1.7 Bolts and screws, except sheet-metal screws, used in the general assembly of iluminating appliances shall have threads conforming to the Standard for Unified Inch Screw Threads (UN and UNR Thread Form), ANSI/ASME B1.1.
4.1.8 Controls shall be accessible for normal servicing and functional adjustment in position and shall be replaceable during normal servicing. Manifold assemblies which permit removal of control(s) intact shall be considered to meet this provision for servicing. Removal of an access panel or door to secure access to a control compartment shall be considered acceptable.
4.2 Materials
4.2.1 On gas-fired iluminating appliances for outdoor installation, metallic structural parts which are exposed to flue products or the outdoor atmosphere shall have a minimum thickness of 0.0254 inch (0.645 mm), except that such parts may be constructed of copper having a minimum thickness of 0.020 inch (0.508 mm).
4.2.2 On gas-fired iluminating appliances for indoor installation, metallic structural parts which are exposed to flue products shall have a minimum thickness of 0.0254 inch (0.645 mm), except that such parts may be constructed of copper having a minimum thickness of 0.020 inch (0.508 mm).CSA ANSI Z21.42-13 pdf download.