min. number of ladder per platform

huangyhg

min. number of ladder per platform
we are designing support platform about 23 ft above ground for cooling towers. i am assuming that required number of caged ladder depends on size of platform. any references? i have searched osha w/o success.
thanks,
ibro v.
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osha may not say how many ladders you need(maybe two would be good), but osha will say how the ladders will be designed as wel as the platform.
richard a. cornelius, p.e.
i'm not aware of a specific requirement either.  tank roofs normally have 1- ladder regardless of size, for example.
as i recall, osha does specify that if used regularly (ie, daily), a stairway should be used rather than a ladder.
have you looked at nfpa 214?
means of egress is discussed in ohsa 1910.35 - 37 (subpart e).  design details for ladders is discussed in 1910.27.  if the platform is just for operations and/or maintenance to the cooling towers i would think only 1 ladder is required.  if the platform is part of a route for plant personnel to exit the area during an emergency then the platform is part of the means of egress and i don't think you could even use a ladder, you would have to use stairs.
nfpa-101-2000 (life safety code)sections 7.2.9.1 (3) and 40.2.2.10 allows ladders as a means of egress to platforms whose intended occupancy doesn't exceed 3 people at any one time.
2 is more popular for us if a platform has signifcant sizes (e.g. 20ft or larger), for access and egress purposes. usually, the number is req'd or determined ay piping or clients.
in process plants, lots of cases, platforms are interconnected by ladders and stairs, no platform is a dead end.
for a "room" meaning any where more than i think 10 people work requires 2 means of egress, fire code.
richard a. cornelius, p.e.