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1910.27(a)
"Design
requirements" -
1910.27(a)(1)
Design
considerations. All ladders, appurtenances, and fastenings
shall be designed to meet the following load requirements:
1910.27(a)(1)(i)
The
minimum design live load shall be a single concentrated
load of 200 pounds.
1910.27(a)(1)(ii)
The
number and position of additional concentrated live-load
units of 200 pounds each as determined from anticipated
usage of the ladder shall be considered in the design.
1910.27(a)(1)(iii)
The
live loads imposed by persons occupying the ladder shall
be considered to be concentrated at such points as will
cause the maximum stress in the structural member being
considered.
1910.27(a)(1)(iv)
The
weight of the ladder and attached appurtenances together
with the live load shall be considered in the design of
rails and fastenings.
1910.27(a)(2)
"Design
stresses." Design stresses for wood components of
ladders shall not exceed those specified in 1910.25. All
wood parts of fixed ladders shall meet the requirements
of 1910.25(b).
For
fixed ladders consisting of wood side rails and wood rungs
or cleats, used at a pitch in the range 75 degrees to
90 degrees, and intended for use by no more than one person
per section, single ladders as described in 1910.25(c)(3)(ii)
are acceptable.
..1910.27(b)
1910.27(b)
"Specific
features" -
1910.27(b)(1)
"Rungs
and cleats."
1910.27(b)(1)(i)
All
rungs shall have a minimum diameter of three-fourths inch
for metal ladders, except as covered in paragraph (b)(7)(i)
of this section and a minimum diameter of 1 1/8 inches
for wood ladders.
1910.27(b)(1)(ii)
The
distance between rungs, cleats, and steps shall not exceed
12 inches and shall be uniform throughout the length of
the ladder.
1910.27(b)(1)(iii)
The
minimum clear length of rungs or cleats shall be 16 inches.
1910.27(b)(1)(iv)
Rungs,
cleats, and steps shall be free of splinters, sharp edges,
burrs, or projections which may be a hazard.
1910.27(b)(1)(v)
The
rungs of an individual-rung ladder shall be so designed
that the foot cannot slide off the end.
1910.27(b)(2)
"Side
rails." Side rails which might be used as a climbing
aid shall be of such cross sections as to afford adequate
gripping surface without sharp edges, splinters, or burrs.
1910.27(b)(3)
"Fastenings."
Fastenings shall be an integral part of fixed ladder design.
..1910.27(b)(4)
1910.27(b)(4)
"Splices."
All splices made by whatever means shall meet design requirements
as noted in paragraph (a) of this section. All splices
and connections shall have smooth transition with original
members and with no sharp or extensive projections.
1910.27(b)(5)
"Electrolytic
action." Adequate means shall be employed to protect
dissimilar metals from electrolytic action when such metals
are joined.
1910.27(b)(6)
"Welding."
All welding shall be in accordance with the "Code
for Welding in Building Construction" (AWSD1.0-1966).
1910.27(b)(7)
"Protection
from deterioration."
1910.27(b)(7)(i)
Metal
ladders and appurtenances shall be painted or otherwise
treated to resist corrosion and rusting when location
demands. Ladders formed by individual metal rungs imbedded
in concrete, which serve as access to pits and to other
areas under floors, are frequently located in an atmosphere
that causes corrosion and rusting. To increase rung life
in such atmosphere, individual metal rungs shall have
a minimum diameter of 1 inch or shall be painted or otherwise
treated to resist corrosion and rusting.
1910.27(b)(7)(ii)
Wood
ladders, when used under conditions where decay may occur,
shall be treated with a nonirritating preservative, and
the details shall be such as to prevent or minimize the
accumulation of water on wood parts.
..1910.27(b)(7)(iii)
1910.27(b)(7)(iii)
When
different types of materials are used in the construction
of a ladder, the materials used shall be so treated as
to have no deleterious effect one upon the other.
1910.27(c)
"Clearance"
-
1910.27(c)(1)
"Climbing
side." On fixed ladders, the perpendicular distance
from the centerline of the rungs to the nearest permanent
object on the climbing side of the ladder shall be 36
inches for a pitch of 76 degrees, and 30 inches for a
pitch of 90 degrees (fig. D-2 of this section), with minimum
clearances for intermediate pitches varying between these
two limits in proportion to the slope, except as provided
in subparagraphs (3) and (5) of this paragraph.
1910.27(c)(2)
"Ladders
without cages or wells." A clear width of at least
15 inches shall be provided each way from the centerline
of the ladder in the climbing space, except when cages
or wells are necessary.
1910.27(c)(3)
"Ladders
with cages or baskets." Ladders equipped with cage
or basket are excepted from the provisions of subparagraphs
(1) and (2) of this paragraph, but shall conform to the
provisions of paragraph (d)(1)(v) of this section. Fixed
ladders in smooth-walled wells are excepted from the provisions
of subparagraph (1) of this paragraph, but shall conform
to the provisions of paragraph (d)(1)(vi) of this section.
..1910.27(c)(4)
1910.27(c)(4)
"Clearance
in back of ladder." The distance from the centerline
of rungs, cleats, or steps to the nearest permanent object
in back of the ladder shall be not less than 7 inches,
except that when unavoidable obstructions are encountered,
minimum clearances as shown in figure D-3 shall be provided.
1910.27(c)(5)
"Clearance
in back of grab bar." The distance from the centerline
of the grab bar to the nearest permanent object in back
of the grab bars shall be not less than 4 inches. Grab
bars shall not protrude on the climbing side beyond the
rungs of the ladder which they serve.
1910.27(c)(6)
"Step-across
distance." The step-across distance from the nearest
edge of ladder to the nearest edge of equipment or structure
shall be not more than 12 inches, or less than 2 1/2 inches
..1910.27(c)(7)
1910.27(c)(7)
"Hatch
cover." Counterweighted hatch covers shall open a
minimum of 60 degrees from the horizontal. The distance
from the centerline of rungs or cleats to the edge of
the hatch opening on the climbing side shall be not less
than 24 inches for offset wells or 30 inches for straight
wells. There shall be no protruding potential hazards
within 24 inches of the centerline of rungs or cleats;
any such hazards within 30 inches of the centerline of
the rungs or cleats shall be fitted with deflector plates
placed at an angle of 60 degrees from the horizontal as
indicated in figure D-5. The relationship of a fixed ladder
to an acceptable counterweighted hatch cover is illustrated
in figure D-6.
1910.27(d)
"Special
requirements" -
1910.27(d)(1)
"Cages
or wells."
1910.27(d)(1)(i)
Cages
or wells (except on chimney ladders) shall be built, as
shown on the applicable drawings, covered in detail in
figures D-7, D-8, and D-9, or of equivalent construction.
1910.27(d)(1)(ii)
Cages
or wells (except as provided in subparagraph (5) of this
paragraph) conforming to the dimensions shown in figures
D-7, D-8, and D-9 shall be provided on ladders of more
than 20 feet to a maximum unbroken length of 30 feet.
1910.27(d)(1)(iii)
Cages
shall extend a minimum of 42 inches above the top of landing,unless
other acceptable protection is provided.
1910.27(d)(1)(iv)
Cages
shall extend down the ladder to a point not less than
7 feet nor more than 8 feet above the base of the ladder,
with bottom flared not less than 4 inches, or portion
of cage opposite ladder shall be carried to the base.
..1910.27(d)(1)(v)
1910.27(d)(1)(v)
Cages
shall not extend less than 27 nor more than 28 inches
from the centerline of the rungs of the ladder. Cage shall
not be less than 27 inches in width. The inside shall
be clear of projections. Vertical bars shall be located
at a maximum spacing of 40 degrees around the circumference
of the cage; this will give a maximum spacing of approximately
9 1/2 inches, center to center.
1910.27(d)(1)(vi)
Ladder
wells shall have a clear width of at least 15 inches measured
each way from the centerline of the ladder. Smooth-walled
wells shall be a minimum of 27 inches from the centerline
of rungs to the well wall on the climbing side of the
ladder. Where other obstructions on the climbing side
of the ladder exist, there shall be a minimum of 30 inches
from the centerline of the rungs.
1910.27(d)(2)
"Landing
platforms." When ladders are used to ascend to heights
exceeding 20 feet (except on chimneys), landing platforms
shall be provided for each 30 feet of height or fraction
thereof, except that, where no cage, well, or ladder safety
device is provided, landing platforms shall be provided
for each 20 feet of height or fraction thereof. Each ladder
section shall be offset from adjacent sections. Where
installation conditions (even for a short, unbroken length)
require that adjacent sections be offset, landing platforms
shall be provided at each offset.
1910.27(d)(2)(i)
Where
a man has to step a distance greater than 12 inches from
the centerline of the rung of a ladder to the nearest
edge of structure or equipment, a landing platform shall
be provided. The minimum step-across distance shall be
2 1/2 inches.
..1910.27(d)(2)(ii)
1910.27(d)(2)(ii)
All
landing platforms shall be equipped with standard railings
and toeboards, so arranged as to give safe access to the
ladder. Platforms shall be not less than 24 inches in
width and 30 inches in length.
1910.27(d)(2)(iii)
One
rung of any section of ladder shall be located at the
level of the landing laterally served by the ladder. Where
access to the landing is through the ladder, the same
rung spacing as used on the ladder shall be used from
the landing platform to the first rung below the landing.
1910.27(d)(3)
"Ladder
extensions." The side rails of through or side-step
ladder extensions shall extend 3 1/2 feet above parapets
and landings. For through ladder extensions, the rungs
shall be omitted from the extension and shall have not
less than 18 nor more than 24 inches clearance between
rails. For side-step or offset fixed ladder sections,
at landings, the side rails and rungs shall be carried
to the next regular rung beyond or above the 3 1/2 feet
minimum (fig. D-10).
1910.27(d)(4)
"Grab
bars." Grab bars shall be spaced by a continuation
of the rung spacing when they are located in the horizontal
position. Vertical grab bars shall have the same spacing
as the ladder side rails. Grab-bar diameters shall be
the equivalent of the round-rung diameters.
..1910.27(d)(5)
1910.27(d)(5)
"Ladder
safety devices." Ladder safety devices may be used
on tower, water tank, and chimney ladders over 20 feet
in unbroken length in lieu of cage protection. No landing
platform is required in these cases. All ladder safety
devices such as those that incorporate lifebelts, friction
brakes, and sliding attachments shall meet the design
requirements of the ladders which they serve.
1910.27(e)
"Pitch"
-
1910.27(e)(1)
"Preferred
pitch." The preferred pitch of fixed ladders shall
be considered to come in the range of 75 degrees and 90
degrees with the horizontal
1910.27(e)(2)
"Substandard
pitch." Fixed ladders shall be considered as substandard
if they are installed within the substandard pitch range
of 60 and 75 degrees with the horizontal. Substandard
fixed ladders are permitted only where it is found necessary
to meet conditions of installation. This substandard pitch
range shall be considered as a critical range to be avoided,
if possible.
1910.27(e)(3)
"Scope
of coverage in this section." This section covers
only fixed ladders within the pitch range of 60 degrees
and 90 degrees with the horizontal.
1910.27(e)(4)
"Pitch
greater than 90 degrees." Ladders having a pitch
in excess of 90 degrees with the horizontal are prohibited.
1910.27(f)
"Maintenance." All ladders shall be maintained
in a safe condition. All ladders shall be inspected regularly,
with the intervals between inspections being determined
by use and exposure.
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