| 1910.24(a)
"Application
of requirements." This section contains specifications
for the safe design and construction of fixed general
industrial stairs. This classification includes interior
and exterior stairs around machinery, tanks, and other
equipment,
and stairs leading to or from floors, platforms, or
pits. This section does not apply to stairs used for
fire exit purposes,
to construction operations to private residences, or
to articulated stairs, such as may be installed on floating
roof tanks
or on dock facilities, the angle of which changes with
the rise and fall of the base support.
..1910.24(b)
1910.24(b)
"Where
fixed stairs are required." Fixed stairs shall
be provided for access from one structure level to another
where
operations necessitate regular travel between levels,
and for access to operating platforms at any equipment
which
requires attention routinely during operations. Fixed
stairs shall also be provided where access to elevations
is daily or
at each shift for such purposes as gauging, inspection,
regular maintenance, etc., where such work may expose
employees to acids, caustics, gases, or other harmful
substances, or for which purposes the carrying of tools
or
equipment by hand is normally required. (It is not the
intent of this section to preclude the use of fixed
ladders for
access to elevated tanks, towers, and similar structures,
overhead traveling cranes, etc., where the use of fixed
ladders
is common practice.) Spiral stairways shall not be permitted
except for special limited usage and secondary access
situations where it is not practical to provide a conventional
stairway. Winding stairways may be installed on tanks
and
similar round structures where the diameter of the structure
is not less than five (5) feet.
1910.24(c)
"Stair
strength." Fixed stairways shall be designed and
constructed to carry a load of five times the normal
live load
anticipated but never of less strength than to carry
safely a moving concentrated load of 1,000 pounds.
1910.24(d)
"Stair
width." Fixed stairways shall have a minimum width
of 22 inches.
1910.24(e)
"Angle
of stairway rise." Fixed stairs shall be installed
at angles to the horizontal of between 30 deg. and 50
deg. Any
uniform combination of rise/tread dimensions may be
used that will result in a stairway at an angle to the
horizontal
within the permissible range. Table D-1 gives rise/tread
dimensions which will produce a stairway within the
permissible
range, stating the angle to the horizontal produced
by each combination. However, the rise/tread combinations
are not
limited to those given in Table D-1.
Table D-1
________________________________________________________
Angle to horizontal | Rise (in inches) | Tread run (in
inches)
__________________________ |____________________________
30 deg. 35'............| 6 1/2 | 11
32 deg. 08'............| 6 3/4 | 10
3/4
33 deg. 41'............| 7 | 10
1/2
35 deg. 16'............| 7 1/4 | 10
1/4
36 deg. 52'............| 7 1/2 | 10
38 deg. 29'............| 7 3/4 | 9
3/4
40 deg. 08'............| 8 | 9
1/2
41 deg. 44'............| 8 1/4 | 9
1/4
43 deg. 22'............| 8 1/2 | 9
45 deg. 00'............| 8 3/4 | 8
3/4
46 deg. 38'............| 9 | 8
1/2
48 deg. 16'............| 9 1/4 | 8
1/4
49 deg. 54'............| 9 1/2 | 8
_______________________________________________________
..1910.24(f)
1910.24(f)
"Stair
treads." All treads shall be reasonably slip-resistant
and the nosings shall be of nonslip finish. Welded bar
grating
treads without nosings are acceptable providing the
leading edge can be readily identified by personnel
descending the
stairway and provided the tread is serrated or is of
definite nonslip design. Rise height and tread width
shall be uniform
throughout any flight of stairs including any foundation
structure used as one or more treads of the stairs.
1910.24(g)
"Stairway
platforms." Stairway platforms shall be no less
than the width of a stairway and a minimum of 30 inches
in
length measured in the direction of travel.
1910.24(h)
"Railings
and handrails." Standard railings shall be provided
on the open sides of all exposed stairways and stair
platforms. Handrails shall be provided on at least one
side of closed stairways preferably on the right side
descending.
Stair railings and handrails shall be installed in accordance
with the provisions of 1910.23.
1910.24(i)
"Vertical
clearance." Vertical clearance above any stair
tread to an overhead obstruction shall be at least 7
feet
measured from the leading edge of the tread.
[39 FR 23502, June 27, 1974, as amended at 43 FR 49744,
Oct. 24, 1978; 49 FR 5321, Feb. 10, 1984]
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