Fire resistance ratings, fireproofing

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 ... 

Fire resistance rating—The time period that a specific fireproofing design will protect structural supports for equipment, piping and so forth from collapse, when exposed to a fire of specified intensity. The fire intensity is usually represented by a time-temperature curve. 

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. 

Fire-resistive insulating material only 2 to 3-hour rated fireproofing 2- to 3-hour rated fireproofing Passive protection potential for unseen corrosion. 

Combination water spray with fire-resistive insulating material 1 to 1V2-hour rated fireproofing plus water spray (as above) 1 to 1V2-hour rated fireproofing plus water spray (as above) Active protection but the passive fireproofing allows some time of protection in event water system fails. 

PVC is inherently resistant to fire but rubbers are not. Consequently, the fire behaviour depends on the PVC/rubber ratio, the formulation and the use of fireproofing agents. Some TPE/PVC grades reach a UL94 VO rating. In the event of fire, beware of the fume toxicity and corrosivity. 

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