Steel fire protection

Carbon steel heat exchangers, cast iron water boxes, screens, pump components, service water system piping, standpipes, fire protection systems, galvanized steel, engine components, and virtually all non-stainless ferrous components are subject to significant corrosion in oxygenated water. 

World Trade Center twin towers, 3000 died, 10 billion loss, insufficient fire protection to steel structure ... 

Steel, aluminum, concrete, and other materials that form part of a process or building frame are subject to structural failure when exposed to fire. Bare metal elements are particularly susceptible to damage. A structural member undergoes any combination of three basic types of stress compression, tension, and shear. The time to failure of the structural member will depend on the amount and type of heat flux (i.e., radiation, convection, or conduction), and the nature of the exposure (one-sided flame impingement, flame immersion, etc.). Cooling effects from suppression systems and effects of passive fire protection will reduce the impact. 

The mitigation (if any)—from cooling water or of passive fire protection on steel. 

Passive protection can be used to increase the time to structural failure. For example, intumescent mastic coatings of less than 1 inch thickness have been shown to provide up to 4 hours of fire resistance when applied to steel columns. Cementitious materials have been shown to provide 1-4 hours fire resistance for thicknesses of 2.5-6.3 cm (1-2.5 in). For additional information on passive fire protection, see Chapter 7. 

Experiments on gas jet fires impinging on steel tubular members by Shell/British Gas (Offshore Research Focus, 1980) evaluated two types of passive fire protection ... 

Measures to reduce the impact of fire include active and passive systems. Active systems include automatic sprinkler, water deluge, water mist, gaseous agent, dry chemical, foam, and standpipe handle systems. Passive protection is provided by fire resistive construction, including spray-applied or cementitious fireproofing of steel, concrete/masonry construction, and water-filled steel columns. Chapter 7 provides details on the design of fire protection systems. 

When the shell of a vessel is exposed to extreme heat on the outside and the inside is in contact with vapor, metal temperatures may reach levels where tensile strength will be reduced such that rupture may occur even though the pressure does not exceed the set point of the pressure relief valve [for ordinary carbon steel, this temperature is 900°F (482°C)]. Vapor depressuring provides fire protection for process units by reducing the contained pressure at such a rate that ... 

Fireproofing is a fire resistant material or system that is applied to a surface to delay heat transfer to that surface. Fireproofing, a form of passive fire protection, protects against intense and prolonged heat exposure that can cause the weakening of steel and eventual collapse of unprotected equipment, vessels, and supports and lead to the spread of burning liquids and substantial loss of property. The primary purpose is to improve the capability of equipment/struc-... 

Fire protection for structural steelwork can be provided by water spray that cools and wets fire exposed surfaces. This active form of fire protection can be used on vertical structural steel columns, horizontal supports and other steelwork. 

A generalized comparison of equivalent fire protection for structural steel using water spray rates recommended in NFPA 15 and fire-resistive insulation used alone or in combination is provided in Table 8-9 (NFPA 15). 

Flame shields on the underside of cable trays have been used effectively to deflect flames or heat emanating from fires below. Flame shields should be fabricated of Xein (1.6-mm) thick steel plate or equivalent mounted below the cable tray and extending a minimum of 6 in (152 cm) beyond the tray side rails. These shields can improve tray survivability usually in concert with water spray systems. Flame shields alone (with no water spray) can provide only brief fire protection and are not normally used in this manner. Flame shields coated with... 

Jet flame contact on the shell of a vessel makes water spray cooling ineffective. The momentum and velocity of medium to large jet flames is such that they will deflect any water spray pattern and thus prevent the local application of cooling to the vessel s shell. The concentrated application of fire water by monitors can provide adequate cooling. Unwetted steel shell subjected to a jet flame can be expected to fail within 10 minutes, thus there are practical difficulties in being able to bring the necessary resources to bear in sufficient time to be effective. Therefore, fireproofing and separation distance are the fire protection options for jet fires. 

Insulators or materials with low heat conduction are often used for fire protection coatings and thermal insulation. This thermal barrier prevents heat reaching and damaging structural steel and process vessels. 

With the advent of dry wall finishes that replace the wet plaster wall finish, additional fire safety problems were presented. The lime, cement, and gypsum plaster previously used provided an incombustible surface and afforded some fire protection to the wood or steel framing of the building but many of the dry wall finishes are themselves combustible, offer little if any resistance to fire, and tend to increase the intensity of a fire by contributing additional fuel. 

F. Buildings constructed of such steel can collapse from the heat of the fire. The word heat-resistant is used in this relation. Heat-resistant, therefore, as used here refers to the thermal conductivity of the fire-protective medium, the mastic. 

Note 1 Substances used as samples for the improved steel dish test are capitalized. Note 2 In case the first digit of the index No. is 1, the substance belongs to the first group of hazardous materials according to the Fire Protection Law. 

Wood and steel samples coated with two kinds of fire-protective and heat-insulating coatings were subjected to testing in accordance with ASTM D1002 to determine... 

A fireproof safe is to be constructed. Its walls consist of two 2-nun steel sheets with a layer of asbestos board between them. Using the chart for a slab, estimate the thickness of asbestos required to give 1 hr of fire protection on the basis that, for an outside temperature of 800 ° C, the inside temperature is not to rise above 120 ° C during this period. The heat transfer coefficient at the exterior surface is 25 W/m2 -K. 

There are other engineering factors that affect the fire and explosion hazard, e.g., engineering standards of the structural steel and foundations, process equipment, heat exchangers, feeding system, fan and blowers, storage vessels, electrical equipment, instruments, and fire protection and safety equipment. Considerable assistance in design also can be obtained from relevant codes of practice. The responsibility for safe operation rests with the manufacturers of equipment and products as required by national law (e.g.. Factories Act and Health and Safety at Work Act in the United Kingdom). 

Full scale experiments on FRP structural members subjected to realistic fire exposure are also necessary. Not only does this supply valuable results and provide confidence for the fire performance of FRP structural members to be used in civil engineering, it also validates the above modeling concepts on the structural level. Similarly, as performed in the fire design of structures made by traditional materials such as steel and reinforced concrete, active and passive fire protection techniques may be necessary for prolonging resistance time of composite materials in fire. Such techniques are reviewed and compared, particularly with regard to their applications for composite materials. 

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