Fireproofed steel

When insulation is used to fireproof steel that will be at or below ambient conditions, caution should be taken to prevent external corrosion of the steel caused by condensation when the steel is below the atmospheric dew point. 

When fireproofed steel construction is used, pipe support steel must be installed before the steel columns, beams, and braces are fireproofed. Otherwise, the fireproofing must be chip )ed away down to the Steel member. This chipping is costly and should be avoided. 

Steel stmctures should be protected by approved fireproofing treatment, eg, concrete or insulating, ie, intumescent or ablative materials untreated steel should be protected by some method of cooling, eg, a water-spray system. 

Need for fireproofed structural steel Process 1. Consequences of exposure to-adjacent ... 

Fireproofing for the petroleum and related industries follow the same concept as other industries except that the possible fire exposures are more severe in nature. The primary destructive effects of fire in the petroleum industry is very high heat, very rapidly, in the form of radiation, conduction and convection. This causes the immediate collapse of structures made of exposed steel construction. Radiation and convection effects usually heavily outweigh the factor of heat conduction for the... 

Cementitious materials use a hydraulically setting cement such as Portland cement as a binder with a filler material of good insulation properties, e.g., verminculite, perlite, etc. Concrete us frequently used for fireproofing because it is easily installed, readily available, is quite durable and generally economical compared to other methods. It is heavy compared to other materials and requires more steel to support that other methods. 

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. 

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-... 

Compatibility—stainless steel and aluminum are susceptible to corrosion from exposure to agents that can be in certain fireproofing material, especially chlorine. 

The major disadvantage of endothermic wrap fireproofing is when used outdoors, the system must be weatherproofed. Stainless steel jacketing or wrapping with a manufacturer s protective tape is necessary to provide the recommended level of protection. 

Before insulation is installed, carbon steel surfaces between 32°F and 200°F (0°C and 93°C) should be prepared and painted in accordance with manufacturer s recommendations. A vapor barrier should be provided over the outer layer of the insulation. Minimum thickness of insulation for fireproofing should be 2 in (5 cm). Moisture contamination to the insulation should be avoided to prevent damage to the insulation as a result of steam pressure caused by a fire. 

Insulation used for fireproofing should be jacketed with 18Cr-8Ni stainless, vinyl-clad galvanized steel or uncoated galvanized steel. Uncoated galvanized steel should not be used below ambient temperature service where corrosion will be accelerated if the galvanized steel is kept wetted from condensation. 

The use of magnesium oxychloride plasters for fireproofing is not recommended. Field experience has indicated that corrosion of the substrate steel occurs as the topcoat (over the fireproofing) weathers and moisture combines with the chloride present in the plaster to form hydrochloric acid. 

Fire resistant insulating material can provide passive protection for both vertical and horizontal structural steel members. The level or rating of fire resistance should be consistent to the expected fire duration. Where only fire resistant insulating material will be used, the material and its installation system should be specified to have a 2- to 3-hour fire rating (UL 1709). In applications using a combination of fixed water spray or sprinkler protection and fire resistant insulation, a 1- to 2-hour fire rating (UL 1709) is frequently specified for the fireproofing. 

Some commonly used fireproofing ratings for structures and equipment are indicated in Table 8-8 (API 2218). Unless otherwise noted, steel structures and... 

The top surface of a beam that requires fireproofing need not be fireproofed when that beam supports steel flooring or piping. 

Wind bracing and structural steel stringer beams running parallel to piping need not be fireproofed. 

Structural steel supports for within-unit process transfer lines should be fireproofed with a 1 - to 2-hour fire resistance rating. 

For equipment, tanks, and vessels containing flammables or heated combustible liquids, their steel structural supports, legs, and anchors should normally be fireproofed for a 2-hour fire resistance rating. Some typical examples of where fireproofing should be applied are ... 

Water Spray and Fireproofing for Structural Steel Protection... 

Mineral wool/cement board—Perforated and solid sheet metal and ladder-type cable trays can be completely enclosed with 1 in (25 mm) minimum thickness mineral wool/cement board panels, or equivalent. The panels should be secured with stainless steel screw and stainless steel bands in (19 mm) wide by 0.02 in (0.5 mm) thick, located no more than 18 in (450 mm) apart. In freezing climates the fireproofing panels should be given a weatherproof coat of paint. The structural strength of the metal cable tray should be adequate to support the weight of the fireproofing. 

Ml electric cable—For critical service applications, mineral insulated (Ml) instrument cable may be used in lieu of fireproofing. Magnesium oxide insulation should be stable at 3,000°F (1,650°C). An outside metal sheath ofcopper or stainless steel should be provided. High-pressure, liquid-tight fittings should be used. 

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. 

When the fireproofing material is applied, coat and set aside several pieces of structural steel for periodic fire-testing over the expected life of the coating (this is not necessary with rigid box or flexible contaminant systems). 

Paper pencil small (3-x-4-in.) cardboard box with lid plaster of Paris or casting plaster water iron skimmer ladle pewter in sheet or ingot form wire (stove pipe) pliers carving tools (simple knife nail file pencil old dental tools or anything that will carve plaster) wire cutters propane torch fireproof surface (casting container of sand) steel wool jeweler s saw and blades files X-ACTO knife C-clamp leaves. 

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