Examples: In North America, grease ducts are made of minimum 16 gauge (1. 6 mm) sheet metal, all welded, and certified openings for cleaning, whereby the ducting is either inherently manufactured to have a specific fire-resistance rating, OR it is ordinary 16 gauge ductwork with an exterior layer of purpose-made and certified fireproofing. Either way, North American grease ducts must comply with NFPA 96 requirements. (i) cable coating (application of fire-retardants, which are either endothermic or intumescent, to reduce flamespread and smoke development of combustible cable-jacketing); (j) spray fireproofing (application of intumescent or endothermic paints, or fibrous or cementitious plasters to keep substrates such as structural steel, electrical or mechanical services, valves, liquefied petroleum gas (LPG) vessels, vessel skirts, bulkheads or decks below either 140ºC for electrical items or ca. 500ºC for structural steel elements to maintain operability of the item to be protected). fireproofing cladding (boards used for the same purpose and in the same applications as spray fireproofing) Materials for such cladding include perlite, vermiculite, calcium silicate, gypsum, intumescent epoxy, Durasteel (cellulose-fibre reinforced concrete and punched sheet-metal bonded composite panels), MicroTherm; (k) enclosures (boxes or wraps made of fireproofing materials, including fire-resistive wraps and tapes to protect speciality valves and other items deemed to require protection against fire and heatan analogy for this would be a safe) or the provision of circuit integrity measures to keep electrical cables operational during an accidental fire