Seguridad en diseños.pdf

SAFETY IN DESIGNS
Prepared and Issued by
CRTC - Health, Environment and Safety Group
Chevron Corporation
Revised: February 1997

PRINTING HISTORY
Safety In Designs
First Edition 1934
Last Revision January, 1986
Second Edition September, 1996
Third Edition February, 1997
Restricted Material
Technical Memorandum
This material is transmitted subject to the Export Control Laws of the United
States Department of Commerce for technical data. Furthermore, you
hereby assure us that the material transmitted herewith shall not be ex-
ported or re-exported by you in violation of these export controls.
The information in this Manual has been jointly developed by Chevron Corporation and its Operating
Companies. The Manual has been written to assist Chevron personnel in their work; as such, it may be
interpreted and used as seen fit by operating management.
Copyright © 1934, 1986, 1996, 1997 by CHEVRON CORPORATION. All rights reserved. This document
contains proprietary information for use by Chevron Corporation, its subsidiaries, and affiliates. All other
uses require written permission.

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Safety In Designs
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February 1997 i
Contents
CONTENTS
Front Matter
Foreword
List of Sections With New Information
List of Abbreviations and Symbols
1.0 Work Space, Access to Equipment and Materials, and
the Use of Wood and Other Combustible Materials
2.0 Railings
3.0 Stairways, Ramps, Stiles, Walkways, and Platforms
4.0 Ladders
5.0 Guards: Mechanical, Hot Surface, and Chemical Spray
6.0 Electrical Equipment
7.0 Rigging Practices
8.0 Scaffolds
9.0 Access for Physically Disabled Employees
10.0 Safety Shower/Eye-Wash Units and Chemical Hazards
11.0 Ventilation
12.0 Miscellaneous

February 1997 ii
Foreword
FOREWORD
Safety In Designs provides a summary of legal standards and Company guide-
lines relating to safe facility design, along with cost-effective recommenda-
tions for meeting them. The figures show, in a simplified manner, how to
design and fabricate facilities that incorporate these standards and guide-
lines.
Safety In Designs is most effectively used when building new facilities or
modifying/upgrading existing facilities. Existing facilities that are safe and
meet legal requirements are not expected to be modified to meet this edition
of Safety In Designs.
The design of safe and complying facilities is the responsibility of local man-
agement. Safety In Designs is a tool to help meet this objective.
The basis for Safety In Designs is OSHA requirements augmented in certain
cases by Company recommendations based on industry practice and Chev-
ron experience. Two examples are:
• Recommended handrail details (Section 2.2, Figure 2.1) show practical,
cost-effective means to design handrails to avoid sharp corners and catch
points that can snag clothing or cause slips, trips and hand injuries.
OSHA standards do not address these details.
• Recommended dimension for ladder cages (Section 4.4 B) is 30 inches
(compared to the OSHA minimum of 28 inches) since some people ex-
perience clearance problems when climbing an OSHA-minimum lad-
der while wearing self-contained breathing apparatus.
NOTES:
1. This edition of Safety In Designs provides the following new features to
better inform the reader on the subject of design safety:
A. OSHAStandards: Where appropriate, Federal and California OSHA
standards corresponding to each section are paraphrased in the
margins for reference. Refer to the current OSHA standard for exact
wording.
B. OSHA Interpretations: In some cases OSHA has issued letters of
interpretation. When applicable, these interpretations have been
included in the margin with the regulation as an additional refer-
ence.
C. Chevron Interpretations: In some cases, a Chevron interpretation is
given based on letters of interpretation on a related issue, or based
on legal decisions.
2. This manual does not contain complete fabrication or construction de-
tails. Please refer to applicable Standard Drawings or other Company
publications for this information.

iii February 1997
Safety in Designs
3. Terms used in this manual:
A. Shall, is required, or must either means a legal requirement (as described
in the margin summary), or is a company recommendation that gener-
ally should be followed unless an analysis shows that comparable safety
is provided by alternate methods.
B. Shouldmeans an advisory recommendation which is applicable in most
cases, but is not required.
C. Preferred or Recommendeddenotes a recommendation that has been gen-
erally and successfully used within the Company, but there are other
choices and methods which are acceptable.
4. Revisions: This manual will be revised as new regulations are promul-
gated and new designs developed. Please use the form in the front of this
manual to suggest changes and new information that will make Safety In
Designs more useful.
5. An asterisk (*) after a section of text indicates that the information in that
section is new or revised as of September 1996.

February 1997 iv
Foreword
LIST OF SECTIONS WITH
NEW INFORMATION
This manual contains information which is new or revised for the 1996 ver-
sion of Safety In Designs. This information is designated in each section by an
asterisk (*). The chart below lists the relevant section and page numbers.
Title/ Page
Section Subsection Containing New Information Numbers
1.0 Work Space, Access to Equipment and Materials,
and the Use of Wood and Other Combustible Materials
1.2 Conditions Which Require Safe Access 1-2
1.3 Access to Equipment and Materials 1-3, 1-4
1.4 Means of Egress 1-8
2.0 General Requirements for Guard Railing,
Stair Railing, and Toeboards
2.2 Conditions Which Require Guard Railing 2-2
2.3 Safety Design Requirements for Guard Railings
and Toeboards 2-6, 2-7
2.4 Steel Guard Railing 2-8
3.0 Stairways, Ramps, Stiles, Walkways, and Platforms
3.3 Design Requirements for Stairways 3-3, 3-8
3.4 General Requirements for Steel Ramps,
Stiles, Walkways and Platforms 3-12
3.8 Requirements for Wood Construction 3-30, 3-31
4.0 Ladders
4.2 All Fixed Ladders 4-3, 4-4
4.4 Fall Protection Features 4-10
5.0 Guards: Mechanical, Hot Surface and Chemical Spray
5.3 Approved Materials for Guards 5-7
5.8 Protecting Personnel from Hot or Cold Surfaces 5-21
6.0 Electrical Equipment
6.2 General Requirements for Electrical Equipment 6-2
6.3 Working Spaces About Electrical Equipment -
General 6-3
6.4 Working Spaces About Electrical Equipment -
600 Volts or More 6-5

v February 1997
Safety in Designs
Title/ Page
Section Subsection Containing New Information Numbers
6.5 Definitions of Hazardous Locations 6-6
6.6 Classification of Equipment 6-11
6.7 Marking of Underground Electrical Installations 6-13
10.0 Safety Shower/Eye-Wash Units and Chemical Hazards
10.3 Hazardous Chemicals 10-12, 10-13
12.0 Miscellaneous
12.3 Identification and Labeling of Pipelines
and Equipment 12-8

February 1997 vi
Foreword
LIST OF ABBREVIATIONS
AND SYMBOLS
SYMBOLS
∠ Angle
Angle, Structural Steel
@ At
C Center Line
C-C Center to Center
C Channel, Structural Steel
φ Diameter
°F Degrees Fahrenheit
% Percent
# Pounds
P Plate
R Radius
10" Rise, 12" Run for Pitch
or Angle to Vertical
L
L
12
10
ABBREVIATIONS
AWS American Welding Society
B.O.L. Bottom of Line
CU.YD Cubic Yard
EQUIV Equivalent
FL. Floor
FT. Foot or Feet
GA. Gauge
I.D. Inside Diameter or Inside Dimension
IWRC Independent Wire Rope Core
LB. (S) Pound(s)
LIN. FT. Linear Foot (Feet)
MAX. Maximum
MIN. Minimum
PSF Pounds per Square Foot
REF. Reference
S4S Surfaced Four Sides
SQ. Square
SCHED. Schedule
ST’D DWG Standard Drawing
ST’L. Steel
TYP. Typical

February 1997 1 • page 1
Section 1 • Work Space, Access to Equipment and Materials, and
1.0 WORK SPACE, ACCESS TO
EQUIPMENT AND MATERIALS, AND
THE USE OF WOOD AND OTHER
COMBUSTIBLE MATERIALS
1.1 SECTION CONTENTS
This section provides guidance for access, work space and work areas.
1.2 Conditions Which Require Safe Access*............................................. 2
1.3 Access to Equipment and Materials* ................................................... 3
1.4 Means of Egress ........................................................................................ 8
1.5 The Use of Wood and Other Combustible Materials .......................... 9
1.6 Notes and References ............................................................................ 10
NOTE: An asterisk (*) after a section of text indicates that the infor-
mation in that section is new or revised as of September 1996.

1 • page 2 February 1997
Safety in Designs
1.2 CONDITIONS WHICH REQUIRE SAFE
ACCESS*
A. AISLES AND FLOORS AND OVERHEAD CLEARANCE
Chevron Guidelines
1. Long aisle space should be 36 inches minimum.
2. Short aisle space shall be 30 inches minimum.
3. Short aisles may be crooked, but long aisles should be
straight.
4. Main walk routes through plants should be 48 inches
minimum. These routes cannot be encroached upon by
individual equipment; e.g., small piping, valves (ex-
tended valve stem position), pipe supports, instruments
or electrical items.
5. A minimum of 6 feet 8 inches overhead clearance from
the ground, floor or platform shall be maintained in aisles
and around equipment, valves, etc. where operators pass.
A preferable height is 8 feet overhead clearance. (7 feet
overhead clearance is required over stairs.)
Fed-OSHA 1910.22 & .30
1. The floor of every workroom shall be maintained
in a clean and, so far as possible, a dry condition.
Where wet processes are used, drainage shall be
maintained, and false floors, platforms, mats, or
other dry standing places should be provided
where practicable.
2. Where mechanical handling equipment is used,
sufficient safe clearances shall be allowed for
aisles at loading docks, through doorways, and
wherever turns or passage must be made.
3. Aisles and passageways shall be kept clear and
in good repair, with no obstruction across or in
aisles that could create a hazard.
4. Permanent aisles and passageways shall be ap-
propriately marked.
5. Aisles shall be provided of sufficient width to per-
mit free movement of employees bringing or re-
moving material. This aisle is to be independent
of working and storage space.
Chevron Interpretation
Chevron interprets this to require an aisle of 22
inches as a minimum.
Cal-OSHA 3272
1. Where aisles or walkways are required, machin-
ery equipment, parts, and stock shall be so
arranged and spaced as to provide clear walkways
or aisles of not less than 24 inches in width and 6
feet 8 inches clear headroom to a safe means of
egress from a building.
2. Where aisles or walkways become hazardous due
to lack of proper definition, they shall be clearly
defined by painting lines, curbing or other method
of marking.
3. Whenever aisles, walkways, or crawlways become
slippery, high-friction surfaces, cleats, coverings,
or other equivalent protection against slipping will
be required.
Cal-OSHA 3273
1. Permanent floors and platforms shall be free of dan-
gerousprojectionsorobstructions,maintainedingood
repair, and reasonably free of oil, grease, or water.
Where the type of operation necessitates working
on slippery floors, such surfaces shall be protected
againstslippingbyusingmats,grates,cleats,orother
methods which provide equivalent protection. Where
wetprocessesareuseddrainageshallbemaintained
and false floors, platforms, mats, or other dry stand-
ing places provided.
I
I
I
I
I

1.3 ACCESS TO EQUIPMENT AND MATERIALS*
A. GENERAL
Chevron Guidelines
1. Provide 30 inches of access space (short passageway)
around equipment, valves, etc. which must be operated
or maintained routinely. Additional space should be pro-
vided when operating or maintenance needs dictate. See
Figures 1.1 and 1.2 for details.
Cal-OSHA 3270
1. Every permanently elevated location where ma-
chinery, equipment, or material which is custom-
arily operated or frequently repaired, serviced, ad-
justed or otherwise handled shall be provided with
a safe platform or maintenance runway. Access
shall be by means of either fixed ladder or perma-
nent ramps or stairways.
2. Every permanent pit, sump or other sunken loca-
tion 30 inches or more in depth, or from which,
machinery, equipment, or materials are custom-
arily operated or frequently repaired, serviced, ad-
justed or otherwise handled shall be provided with
a portable or fixed ladder or permanent stairway.
(Also see Section 1.3 B, Access To Controls and
Handwheels.)
Cal-OSHA 3273
1. Catwalks shall be no less than 18 inches wide
and have 6 feet 6 inches clear headroom.
B. ACCESS TO CONTROLS AND HANDWHEELS
Chevron Guidelines
1. Controls such as valve handwheels, levers, wrenches,
lubricators, instruments, machinery controls, or other
equipment requiring manual operation should be in
safely accessible locations and should not obstruct ac-
cess clearances in all operated positions.
2. Valve handwheels operated from elevated platforms 10
feet or more above grade should be located within the
confines of the platform railing. Valve handwheels oper-
ated from outside the platform railing should be posi-
tioned in accordance with Figure 1.3.
3. Root, block, vent, and drain valves for pressure and level
instruments can be accessed from a ladder, if located no
more than 24 inches from the ladder stringer and no more
than 45° from the plane of the ladder.
4. Two-handed operationof valves or equipmentfrom a lad-
der is prohibited.
Cal-OSHA 3272(b)
1. Valves or other controls shall not be so located
that their manipulation exposes the employee to
hazards of dangerous moving parts of prime mov-
ers, machines, or transmission equipment.
Cal-OSHA 3274
1. Where pipe valves require daily manipulation and
are so located that they cannot be reached or op-
erated from the floor, a permanent platform or other
safe means of operation shall be provided.
Cal-OSHA 6846
1. Safe access shall be provided to all valves or their
remote controls, whenever it is necessary to op-
erate them.
2. The following valves, or their remote controls, shall
be provided with means of ready and safe access:
• valvesmanuallyoperatedasoftenasonceashift
• valves on fuel lines to a plant, unit, or internal
combustion engine
• valves on lines, which may be used during
emergency operations

Safety in Designs
Cal-OSHA 6846
1. If a permanently attached handle is used on a quar-
ter turn valve, it shall be installed or placed on the
valve in such a position that the handle is at right
angles to the line when in the closed position, and
parallel with the line when in the open position. If
compliance with the provisions of this subsection
obstructs a passageway or walkway, the handle
may be bent so as to provide clearance.
C. OPERATING VALVE HANDLE AND HANDWHEEL
INSTALLATION
Chevron Guidelines
1. 3-inch clearance should be maintained all around valve
handwheels. 1-1/2 inch and smaller valves where op-
eration is by hand or wrist motion may have less clear-
ance if finger clearance is provided.*
2. Extension handles may be used for locating valve hand-
wheel at proper elevation or providing adequate clear-
ances. “High-head” extensions fitted with handwheels
are preferred, but where accessibility for lubrication and
maintenance is not a problem, tee-handle socket exten-
sions are acceptable. See Figure 1.4 for details.
Figure 1.1 Typical Valve and Piping Layout at Low Walks

Figure 1.2 Valve Arrangement for Access from Walkways

Safety in Designs
Figure 1.3 Guidelines for Installation of Valves (Valve Stem Straight Up
is Preferred Orientation)

Figure 1.4 Guidelines for Installation of Valves with Horizontal Valve Stem

Safety in Designs
1.4 MEANS OF EGRESS
A. INDUSTRIAL BUILDINGS FOR OFFICE USE*
Chevron Guidelines
1. Refer to the guidelines in Section 3.3 E, “Doors and Land-
ings forAccess/Egress of Buildings (Incl. Portable Build-
ings for Office Use).”
B. CONDITIONS WHICH REQUIRE SECONDARY
EGRESS FROM INDUSTRIAL BUILDINGS AND
STRUCTURES
Chevron Guidelines
1. A secondary means of egress (which may be a ladder or
second stairway) is required:
• for elevated work locations 10 feet or more above
grade or floor which have 200 square feet or more
area, or
• for elevated locations where a potential hazard or in-
jurious chemical exposure may block access to an exit.
2. The location of this secondary means of egress shall be
such that an alternate means of escape to a place of safety
is provided. Multiple exits for an area should be located
as far from each other as possible, but not more than 75
feet from any point where employees may be present
unless automatic sprinkler protection is provided.*
Fed-OSHA 1910.23
1. Every building or structure, section, or area there
of such size, occupancy, and arrangement that the
reasonable safety of numbers of occupants may
be endangered by the blocking of any single means
of egress due to fire or smoke, shall have at least
two means of egress remote from each other, so
arranged as to minimize any possibility that both
may be blocked by any one fire or other emer-
gency conditions.
Cal-OSHA 3222 (b)
Note: The arrangement of exits and the distance to
exits must comply with the requirements of Cal-OSHA
3222. The distance to exits must be reduced if the ex-
ception to 3222(b) applies.
1. EXCEPTION: Every area used mainly for the stor-
age of materials liable to burn, with extreme rapid-
ity or from which poisonous fumes or explosions
will result upon exposure to fire, shall have an exit
within 75 feet of any point in the area where em-
ployees may be present. Where automatic sprin-
kler protection is provided, distances may be in-
creased to 100 feet.
Cal-OSHA 3228 (h)
1. Every working area specified below shall be pro-
vided with at least two exits so located with re-
spect to each other as to provide an alternate
means of escape to a place of safety:
• Elevated platforms 10 feet or more above ground
or floor or pits 30 inches or more in depth, hav-
ing 200 or more square feet of area, floors or
rooms in or on which are located steam, gas, oil
or air engines, motors, compressors, steam or
(continued next page)
Note: Exits must comply with the requirements of
1910.35 - .37, “Means of Egress.”
Cal-OSHA 3235
1. Buildings or structures used for human occupancy
shall have at least 1 approved exit door per the
requirements of 3235.
Fed-OSHA 1910.36(b)(8)

hydraulic turbines or pumps, mixing vats, pans,
tanks, or chemical processing equipment and
where the absence of a second exit would in-
crease the risk of injury from hot, poisonous,
corrosive, suffocating, flammable, or explosive
substances.
Cal-OSHA 6799
1. Two means of egress shall be provided in the fol-
lowing situations when employees must perform
operating duties and when the lack of a second
means would prevent the egress... in case of fire
or other emergency:
• any elevated platform 10 feet or more above
the floor or ground level
• on fired process equipment
• where the platform serves or is connected to 3
or more vessels
The means of egress may be by fixed ladder, stair-
way... and shall be so located relative to each
other as to provide reasonably safe alternative
means of egress.
1.5 THE USE OF WOOD AND OTHER
COMBUSTIBLE MATERIALS
A. GENERAL REQUIREMENTS
1. The use of combustible building materials such as wood
and fiberglass in areas of hydrocarbon storage and han-
dling is not recommended due to the increased fire load,
the possibility of spreading the fire, and the risk of flash
back following extinguishment. The use of non-combus-
tible building materials such as steel or concrete is pre-
ferred.
B. NEW CONSTRUCTION
1. The use of combustible materials for walkways, plat-
forms, ladders, and stairs is not acceptable if their involve-
ment in a fire could:
• spread the fire to a tank top, another tank basin, plant
or process area
• increase the damage to important equipment, struc-
tures or controls
• prevent access to important valves and controls dur-
ing or immediately following the fire
2. The use of combustible materials is acceptable for tem-
porary walkways, platforms, scaffolding, etc., providing
they meet other requirements of this manual.
3. The use of combustible material including wood or fiber-
glass is acceptable in corrosive atmospheres such as fertil-
izer plants, cooling water towers, and some chemical areas.

Safety in Designs
C. EXISTING FACILITIES
1. Combustible building materials in the areas listed below
can remain in use until replacement or repair becomes
necessary. At that time non-combustible materials such
as steel and concrete shall be used. No new wood is to
be installed in these areas:
• inside tank impound basins or diked areas if the tank
contains Class I flammable liquids (flash < 100°F)
• for stairs on tanks containing Class I or II flammable
and combustible liquids (flash < 140°F)
• for tank manifold platforms
• for access to large or critical pump or piping mani-
folds
• for on plot labs, sheds, or other buildings in facility
handling, storing, or processing Class I or Class II
flammable and combustible liquids and gases
1.6 NOTES AND REFERENCES
ADDITIONAL REFERENCES
CRTC Standard Drawing GB-L99961
“Standard Valve Installation Guide”

Fed-OSHA 1910.23
Section 2 • Railings
2.0 RAILINGS
This section provides guidance for the design, use, and application
of railings and toeboards. Designs for both steel and wood construc-
tion are included in this section. Steel construction is preferred and
should be considered first. Use of wood should be minimized. See
Section 1.5 for additional guidelines.
2.2 General Requirements for Guard Railing,
Stair Railing, and Toeboards ................................................................... 2
2.3 Safety Design Requirements for Guard Railings
and Toeboards............................................................................................ 6
2.4 Steel Guard Railing ................................................................................... 8
2.5 The Use of Wood for Handrails ............................................................ 12

Fed-OSHA 1910.23
Safety in Designs
2.2 GENERAL REQUIREMENTS FOR GUARD
RAILING, STAIR RAILING, AND TOEBOARDS
A. CONDITIONS WHICH REQUIRE GUARD RAILING
Chevron Guidelines
1. Platforms, walkways, ramps, and floors with open sides
which have 4 or more risers or which are 30 inches or
higher above the adjacent floor or ground level require
guard railings.*
2. Open sides are those with 3 inches or more gap between
platform edge and nearest solid structure, equipment or
wall. In such case a standard guardrail is required.
3. Floor openings 12 x 12 inches or greater which are left
exposed and unattended require guard railings or barri-
ers.
4. Wall openings 30 inches in height by 18 inches in width,
or larger require a standard guardrail or equivalent bar-
rier if a fall through the opening to a level 30 inches or
more below is possible.
5. Platforms, walkways, ramps, and floors above or adja-
cent to dangerous equipment or dangerous hazards re-
quire guard railings regardless of platform, walkway,
ramp, or floor height.
B. CONDITIONS WHICH REQUIRE TOEBOARDS
Chevron Guidelines
1. Platforms, walkways, ramps, and floors with open sides,
48 inches or more above areas where a person can pass
or where portable tools, parts, or material are likely to be
used, require toeboards.
2. Platforms, walkways, ramps, and floors with open sides,
at any elevation above areas with moving machinery or
other equipment with which falling material could cre-
ate a hazard, require toeboards.
3. A toeboard is also required under the first tread of stairs
ascending at the open side from platforms, walkways, or
floors which require toeboards (see Figure 2.1).
1. Permanent floor openings for such purposes as
stairways, ladders, etc. require a standard guard-
rail except at the entrance. Other floor openings
require either a standard guard railing or a floor
opening cover.
OSHA Definition (1910.21)
A floor opening is an opening 12 inches or more in
its least dimension through which a person may
fall.
2. The maximum allowable floor opening where a
person cannot accidentally walk, such as around
machinery and equipment, is 1 inch.
3. Platforms, walkways, ramps and floors with open
sides which are 48 inches or higher above the ad-
jacent floor or ground level require guard railings.
Note: 30 inches in California
4. Platforms, walkways, ramps and floors adjacent
to dangerous equipment or dangerous hazards re-
quire railings regardless of platform, walkway,
ramp, or floor height.
5. Wall openings left exposed or unattended require
a guard railing or equivalent barrier if a fall through
the opening to a level 48 inches or more is pos-
sible.
OSHA Definition (1910.21)
A wall opening is an opening 30 inches in height
by 18 inches in width, or larger through which a
person may fall.
6. Window wall openings, where the bottom of the
opening is less than 36 inches above the floor,
platform, or landing require guarding equivalent to
a standard guard rail, if a fall through the opening
to a level 48 inches or more is possible.
sides 48 inches or more above where a person
can pass or where portable tools, parts, or materi-
als are likely to be used, require toeboards.
Note: 6 feet in California
sides, at any elevation, above areas with moving
machinery or other equipment with which falling
material could create a hazard, require a toeboard.

Fed-OSHA 1910.23
Figure 2.1 Stair Rail Terminations and Connections
Left side shows connection to straight ahead platforms and right side
shows connection to intersecting walkway.

Fed-OSHA 1910.23
Safety in Designs
4. Floor holes or gaps require a toeboard if the least dimen-
sion is greater than 1 inch (see Figure 2.2).
5. Floor holes or gaps may be covered provided the cover
does not present a tripping hazard (see Figure 2.2).
Figure 2.2 Gage Well Cover Plates

Fed-OSHA 1910.23
C. CONDITIONS WHICH REQUIRE STAIR
HAND/GUARD RAILING
Chevron Guidelines
1. Open sides of stairs which have 4 or more risers or which
are more than 30 inches above adjacent floor or ground
level at any point along the stairs require stair railings
(open sides are those with 6 inches or more gap between
stair stringer and nearest solid structure, equipment, or
wall).
2. Stairs with enclosed sides which have 4 or more risers
require at least one stair railing or handrail on one side
(preferably on the right side when descending).
3. Stairs wider than 44 inches may require additional stair
railings and/or handrails (see 29 CFR 1910.23(d)).
4. Figure 2.1 and Figure 2.3 show typical arrangements for
steel railings, terminations and connections.
Figure 2.3 Typical Steel Stair Rail
1. Open sides of stairs which have 4 or more risers
require a standard stairway railing having a verti-
cal height of 30 - 34 inches from the upper sur-
face of top rail to surface of tread in line with face
of riser at forward edge of tread.
2. Stairs with enclosed sides which have 4 or more
risers require at least a handrail on one side (pref-
erably on the right side when descending).
Note: Stairs wider than 44 inches may require
additional hand/guard railings (see 29 CFR
1910.23 (d)).

Fed-OSHA 1910.23
Safety in Designs
1. All types of railing (steel, wood, etc.) must with-
stand anticipated loads - but not less than 200 lb.
at any point and in any direction when applied to
the top rail.
2.3 SAFETY DESIGN REQUIREMENTS FOR
GUARD RAILINGS AND TOEBOARDS
A. DESIGN*
1. A standard guard railing consists of a top rail and a mid-
rail. The top rail shall have a vertical height of 42 inches
from the upper surface of the top rail to the floor or plat-
form. The midrail centerline shall be 21 inches below
the top rail centerline.
2. Astandard stairway railing consists of a top rail and mid-
rail. The construction is similar to a standard guardrail,
except that the top rail on stair railing serves as a hand-
rail. The top railing shall have a vertical height of 30 - 34
inches from the upper surface of the top rail to the sur-
face of the tread in line with the face of the riser at the
forward edge of the tread.
3. The 30 inch stairway handrail height is most commonly
used. The 34 inch handrail height may be used on cir-
cumferential stair railings.
4. All types of railing (steel, wood, etc.) must withstand an-
ticipated loads - but not less than 200 lb. at any point and
in any direction when applied to the top rail.
B. RAILING CLEARANCE
Chevron Guidelines
1. A minimum clearance of 3 inches along the top rail, or
handrail, shall be maintained.*
2. Equipment should not be attached to top rails. Where
attachments to the top rail are unavoidable, use a Z-type
connection as shown in Figure 2.4, or other arrangement
which maintains the minimum clearance.
C. GAPS IN GUARD RAILING
Chevron Guidelines
1. The allowable clear opening of gaps in guard railing on
platforms, walkways, ramps, or floors should not be more
than 3 inches.
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1. All handrails and railings shall be provided with a
clearance of not less than 3 inches between the
handrail or railing and any other object.
Note: 1-1/2 inches in California
OSHA Interpretation
Aclearance of 1-1/2 inches is allowed. [Fed-OSHA
Instruction Std. 1-1.6, (10-30-78)]

Fed-OSHA 1910.23
D. CORNERS AND EDGES
Chevron Guidelines
1. Exposed corners, edges, burrs or rough spots on guard-
rails, stair rails, and handrails shall be ground or filed
smooth. Welds should be ground or filed smooth, but
not flush with the metal surface.*
E. TOEBOARDS
Chevron Guidelines
1. The maximum allowable clear horizontal opening at the
toeboard is 1 inch. Gaps at toeboards should be avoided
where possible.
2. The maximum allowable toeboard gap above the surface
of the platform, walkway, ramp or floor is 1/4 inch verti-
cally and 1/4 inch horizontally.
3. Toeboard thickness should be 1/4 inch minimum.
1. The top rail of guardrail shall be smooth-surfaced
throughout the length of the railing.
1. A standard toeboard is 4 inches nominal in verti-
cal height from its top edge to the level of the plat-
form, walkway, ramp or floor.
OSHA Interpretation
3-1/2 inches is allowed. [ANSI A12.1-1967 incor-
porated by reference 1910.31]
2. The maximum allowable toeboard gap above the
surface of the platform, walkway, ramp or floor is
1/4 inch.
The maximum allowable gap is 1/4 inch vertically
and 1/4 inch horizontally.
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Figure 2.4 Equipment Attachment to Top Rail
Note: 3 inch clearance for both top and sides of top rail,
and that attachment connection is at bottom of top rail.

Fed-OSHA 1910.23
Safety in Designs
2.4 STEEL GUARD RAILING
A. GENERAL REQUIREMENTS FOR STEEL GUARD
RAILING
Chevron Guidelines
1. The dimensions for a standard guardrail are provided in
Figure 2.5.
2. Figure 2.6 shows only two of several acceptable bolted
supports.
3. 1-1/4 inch schedule 40 pipe is the preferred material for
handrails and midrails.
4. Angle posts are preferred because of ease of fabrication.
However, 1-1/2 inch schedule 40 pipe may be used as
shown in Figure 2.5.
5. Fabrication by welding is always preferred.
B. REMOVABLE STEEL GUARD RAILING
Chevron Guidelines
1. Removable steel guard railing may be used to facilitate
the removal of equipment or material handling, provided
the safety of personnel is not jeopardized.
2. Figure 2.7 shows only one of several acceptable supports.
3. Brace bar shall be installed on the platform side of re-
movable handrails to prevent outward movement.
4. Provide a 2-inch clearance between fixed and removable
railing, except at the toeboard where the gap should be 1
inch maximum.
C. TANK ROOF STEEL GUARD RAILING
Chevron Guidelines
1. Tanks with diameters of 20 feet or less should have a
guardrail and toeboard around the entire roof if access to
the roof is required. (Not required when railed walk-
ways and platforms are provided).* See Figure 2.8.
1. A standard guard railing consists of a top rail,
midrail and toeboard and has a vertical height of
42 inches nominal from the top of the rail to the
upper surface of the platform, walkway, ramp or
floor. The midrail shall be approximately halfway
between the top rail and the platform, walkway,
ramp or floor. The ends of the rails shall not over-
hang the terminal posts where such overhang cre-
ates a projection hazard.
OSHA Interpretation
The maximum opening between the top rail and
the midrail is 19 inches. [Fed-OSHA Instruction
Std. 1-1.10, (6-30-81)]
2. Pipe top rails, midrails and posts shall be at least
1-1/2 inches nominal diameter with posts spaced
no more than 8 feet on centers.
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Fed-OSHA 1910.23
Figure 2.5 Typical Welded Guardrail for Platforms, Walkways, Ramps, and Floors
Figure 2.6 Bolted Connection Alternatives
Where hot work is restricted, top rail, midrail, and rail post may be shop-welded together, and
the assembled guardrail may be bolted to equipment or structure as shown. Other bolting
arrangements may be used providing railing design requirements are met.

Fed-OSHA 1910.23
Safety in Designs
2. Tanks with diameters greater than 20 feet require a stan-
dard guardrail including a toeboard along the roof pe-
rimeter extending 8 feet from the designated work area
or 8 feet beyond the roof platform entrance (Figure 2.9).
3. Unusual circumstances may require running rail com-
pletely around tanks greater than 20 feet in diameter. Ex-
ample - in locations where heavy snow requires shovel-
ing off a tank’s roof, the roof should be completely en-
closed by a standard railing (including a toeboard).
Figure 2.7 Removable Steel Guard Railing and Support

Fed-OSHA 1910.23
Figure 2.8 Total Enclosure for Roof
of 20'0" Diameter or Smaller Tanks
Figure 2.9 Partial
Enclosure for Roof of
Tanks with Diameters
Greater than 20'0"

Fed-OSHA 1910.23
Safety in Designs
2.5 THE USE OF WOOD FOR HANDRAILS
A. CHEVRON REQUIREMENTS FOR THE USE OF WOOD
General Requirements
1. See Section 1.5, Chevron requirements for use of wood.
B. GENERAL REQUIREMENTS WOOD GUARD RAILING
Chevron Guidelines
1. Figure 2.10 shows only two of several acceptable supports.
2. Lumber shall be construction grade Douglas fir or equal.
3. All wood to be surfaced four sides (S4S). Top rails shall
be smooth and have corners rounded.
4. It is preferable to mount top rail on top of the posts but
they may be mounted on the inside of the posts. Midrails
and toeboards should always be on the inside of the posts.
Suggested Fabrication Details
5. Fasteners should be galvanized. Attach top rail and mid-
rail top post with one 20d and two 8d nails. Attach toe-
board to post with three 8d nails. (1/2-inch carriage bolts
may be used in lieu of nails.) Attach posts to walkway
stringers with two 1/2-inch machine bolts with washers
placed at a minimum of 2 inches from edges of stringers.
Note: See Section 2.2 A for OSHA design require-
ments for guard rails of all types.
1. Wood top rails, midrails, and posts shall be at least
2 inch x 4 inch stock. Spacing of posts shall not
exceed 6 feet. If the top rail is made of at least
two right angle pieces of 1 x 4 inch stock, posts
may be spaced on 8-foot centers.
2. When used, hardwood handrails must be at least
2 inches in diameter.
Figure 2.10 Wooden Guardrail for Platforms,
Walkways, Ramps, and Floors
Post spacing may be increased to 8'0" max.
C-C with alternative top rail design.

Fed-OSHA 1910.23
Note: See Section 2.2 C for OSHA design require-
ments for stairway hand/guard rails of all types.
Figure 2.11 Typical Stair Railing and Terminations
C. WOOD STAIRWAY HAND/GUARD RAILING AND
TERMINATIONS
Chevron Guidelines
1. Railing designs different from those in Figure 2.11 may be
used as long as they are capable of withstanding any an-
ticipated loads and meet design requirements.
2. Sills should be rough construction treated Douglas fir or
equal. Other lumber to be construction grade Douglas fir.
3. Wood, except sills, shall be surfaced four sides. Hand-
rails shall be smooth and have corners rounded.

Fed-OSHA 1910.23
Safety in Designs
Note: See Section 2.2 C for OSHA design require-
ments for stairway handrails and guardrails of all types.
Figure 2.12 Stair Rail Connections
Left Side shows connection to straight ahead platforms and right side shows
connection to intersecting walkway.
D. WOOD STAIRWAY HAND/GUARD RAILING
CONNECTIONS
1. All fasteners should be galvanized. Attach handrails and
midrails to posts with one 20d and two 8d nails. (1/2-
inch carriage bolts may be used in lieu of nails.) Attach
posts to stringers with two 1/2-inch carriage bolts with
washers placed a minimum of 2 inches from edge of
stringer.
2. It is preferable to mount handrails on top of the posts but
they may be mounted on the inside of the posts. Midrails
and toeboards should always be on the inside of the posts.

Fed-OSHA 1910.23
OTHER GUIDES
24 Cal. Code of Regs. 2-3305 State Building Code
“Stairways”
Uniform Building Code Section 1711
“Guardrails”
A1264.1-1995 ANSI Standard
“Safety Requirements for Floor and Wall Openings, Stairs, and
Railing Systems."
CRTC Standard Drawing GF-M99645
“Standard Railing”

Fed-OSHA 1910.24
Section 3 • Stairways, Ramps, Stiles,
Walkways, and Platforms
3.0 STAIRWAYS, RAMPS, STILES,
WALKWAYS, AND PLATFORMS
This section provides guidance for the design and use of stairways,
ramps, walkways, and platforms. Designs for both steel and wood
construction are included in this section. Steel construction is pre-
ferred and should be considered first. Use of wood should be mini-
mized. See Section 1.5 for additional guidelines.
3.2 General Requirements for Stairways .................................................... 2
3.3 Design Requirements for Stairways...................................................... 2
3.4 General Requirements for Steel Ramps, Stiles,
Walkways and Platforms....................................................................... 12
3.5 Typical Steel Tank Gauging Platforms ................................................ 17
3.6 General Requirements for Walkways
and Platforms for Tanks ......................................................................... 23
3.7 Bolted Stairways and Walkways......................................................... 27
3.8 Requirements for Wood Construction ................................................ 28

Fed-OSHA 1910.24
Safety in Designs
3.2 GENERAL REQUIREMENTS FOR STAIRWAYS
A. CONDITIONS WHICH REQUIRE FIXED STAIRWAYS
AS ACCESS
Chevron Guidelines
1. Stairways are required for access to and egress from el-
evated work platforms, walkways, and other elevated
work areas where the frequency of use is daily.
2. Stairways should be provided for access to elevated plat-
forms, walkways, and other elevated work areas where
the frequency of use is less than daily:
• if material, tools or other equipment must be carried
for operating or maintenance requirement, or
• if there is a potential for exposure to injurious chemi-
cals or materials at the elevated location.
3. Refer to the discussion in Section 1.4 B regarding second-
ary means of egress.
Fed-OSHA 1910.24
1. Fixed stairways are required:
• for access from one structure level to another
where operations necessitate regular travel be-
tween levels
• for access to operating platforms at any equip-
ment which requires attention routinely during
operations
• when access to elevations is daily or at least
once each shift for activities such as gaging,
inspection, regular maintenance, where
- such work may expose workers to acids,
caustics, gases or other harmful sub-
stances
- the carrying of tools by hand is normally
required
2. The use of fixed ladders is not precluded for ac-
cess to tanks, towers and similar structures where
the use of fixed ladders is common practice.
3. Spiral stairs are not permitted except for special
limited usage and secondary access situations
where it is not practical to provide conventional
stairs.
4. Winding stairs may be installed on tanks and simi-
lar round structures where the diameter of the
structure is not less than 5 feet.
3.3 DESIGN REQUIREMENTS FOR STAIRWAYS
A. GENERAL REQUIREMENTS FOR STAIRWAYS
Chevron Guidelines
1. The recommended maximum rise height in a stairway
or stile is 8 inches, except for a single step riser which
may have a 12-inch maximum rise height.
2. The recommended minimum tread run in a stairway or
stile is 9-1/2 inches.
3. The greatest rise height within any flight of stairs shall
not exceed the smallest by more than 3/8 inch.
4. The largest tread run within any flight of stairs shall not
exceed the smallest by more than 3/8 inch (see Figure 3.1).
5. Design Load:
Stairways shall be built to carry 5 times the normal an-
ticipated live load, but not less than a 1000 lbs. moving
concentrated load.
I
1. Fixed stairs shall be designed and constructed to
carry a load of 5 times the normal load anticipated,
but never of less strength than to carry safely a
moving concentrated load of 1,000 lbs.
2. All treads shall be reasonably slip resistant and
the nosing shall be of non-slip finish.
OSHA Interpretation
Each tread and top landing of a stairway, where
risers are used, should have a nosing which ex-
tends 1/2 - 1 inch beyond the face of the lower
riser. Noses should have an even leading edge.
[ANSI A64.1-1968 incorporated by reference
1910.24]

Fed-OSHA 1910.24
OSHA Interpretation
Avoid long flights of stairs, unbroken by landings
or intermediate platforms. [ANSI A64.1-1968 in-
corporated by reference 1910.24]
3. Welded bar grating treads without nosing are ac-
ceptable provided the leading edge can be readily
identified by personnel descending the stairway
and provided the tread is serrated or is of definite
non-slip design.
OSHA Interpretation
Stairs having less than 9-inch width should have
open risers. [ANSI A64.1-1968 incorporated by
reference 1910.24]
4. Rise height and tread width shall be uniform
throughout any flight of stairs, including any foun-
dation structure used as one or more treads of
the stairs.
This means that treads and risers shall deviate
no more than 3/8 inch in uniformity throughout
any flight of stairs.
Note: Uniformity is extremely critical at the top
step of a long flight of stairs.
5. Fixed stairs shall have a minimum width of 22
inches.
6. Stairway platforms shall be no less than the width
of a stairway and a minimum of 30 inches in the
direction of travel.
7. 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.
Note: Refer to Section 2.2 C.
8. Vertical clearance above any stair tread to an
overhead obstruction shall be at least 7 feet, mea-
sured from the leading edge of the tread.
Cal-OSHA 3234
1. The maximum variations in the height of risers or
the width of treads in any one flight shall be 1/4
inch.
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Figure 3.1 Stairway Terms
6. Landings:
Coordinate layout of stair landings for tanks and vessels
during foundation design to avoid interferences. See
Section 3.3 D.
7. Intermediate Landings:
Recommended vertical rise between landings on a stair-
way is maximum 24 risers or 16 feet 0 inches. Occasional
use stairways may not require intermediate landings.
8. Clear Pathway:
30 inch minimum width is required for egress stairways
and stiles.
9. Treads:
All steel stairs should have treads made of serrated grat-
ing.* (Refer to Figure 3.7.)
10. Nosing:
Treads shall have an even leading edge and be of non-
slip design. Nosing shall extend 1/2 inch to 1 inch over
risers.
11. Overhead Clearance:
7 feet 0 inches minimum vertical clearance shall be pro-
vided from the top of each tread at the leading edge, in-
cluding platform edge.

Fed-OSHA 1910.24
Safety in Designs
Suggested Fabrication Detail
12. Figures 3.2 and 3.7 provide suggested fabrication details
for steel stairs.
Figure 3.2 Steel Stairway and Stair Landing
Note 1: See Section 3.3 D-2.

Fed-OSHA 1910.24
C. STAIR SLOPE
Chevron Guidelines
1. Stair slopes should have angles to the horizontal of be-
tween 30° and 40°.
2. The recommended standard or rise height/tread run of
new stair construction is 7-3/4 inches/9-3/4 inches (stair
slope = 38°29'). This rise height/tread run may be ad-
justed so that the rise height between top or bottom tread
and platform or floor conforms with the uniform rise
height between treads on a flight of stairs.
3. Whenever possible, maintain a uniform slope of all stair-
ways in a plant or area. See Figures 3.4 and 3.5 for details.
1. Fixed stairs shall be installed at angles to the
horizontal of between 30o
and 50o
. Any uniform
combination of rise/tread dimensions may be used
that will result in a stairway at an angle to the
horizontal within the 30o
and 50o
range.
B. SUMMARY OF HANDRAIL & GUARDRAIL
REQUIREMENTS FOR STAIRS AND PLATFORMS
Chevron Guidelines
1. Figure 3.3 provides a summary of the requirements for
stairways and platforms.
Figure 3.3 Stair and Platform Requirement Summary
NOTE 1: Required for special hazards only (see Section 2.2 A)
NOTE 2: Intermediate landings are recommended for stairway to platform heights 16'0"
or greater. In some jurisdictions, Intermediate landings are required for stairway
to platform heights 12'0" or greater. Intermediate landings may not be required
for occasional use stairways.
STAIR OR PLATFORM TYPE
STAIR RAIL
HANDRAIL
PLATFORM
GUARDRAIL
PLATFORM
TOEBOARD
INTERMEDIATE
LANDING
1. Single Riser None Note 1 Note 1 None
2. Two to three risers and platform
heights less than 30”
Note 1 Note 1 Note 1 None
3. Four or more risers or platform
heights 30” to 48”
Required Required for
open sides
Note 1 None
4. Platform Heights
48” or greater
Required Required for
open sides
Required for
open sides
Note 2

Fed-OSHA 1910.24
Safety in Designs
D. STAIR LANDINGS
Chevron Guidelines
1. 30 x 30 inch minimum landing area is required for the base
and top of stairways and stiles and for intermediate land-
ings.
2. Use of separate landing pads should be avoided where
possible. However, where stairways lead to an uneven grade,
or where it is infeasible to adjust stair slope for the require-
ment of uniform stair risers in a flight of stairs, a minimum
30 x 30 inch stair landing may be installed so that a uniform
stair riser is provided between the tread and stair landing.
3. The stair landing is built up from grade to make up the
height of any uneven or non-uniform rise (see Detail A in
Figure 3.2).
1. Stairway platforms shall be no less than the width
of a stairway and a minimum of 30 inches in length
in the direction of travel.
WHICH WILL BE LEGALLY
ACCEPTABLE IN MOST
JURISDICTIONS
RISE HEIGHT
(INCHES)
TREAD RUN
(INCHES)
6 1/2 11
6 3/4 10 3/4
7 10 1/2
7 1/2 10
7 3/4 9 3/4
8 9 1/2
Figure 3.4 Range of Slopes for Stairs
and Ramps
Ref. Std. Dwg. GD-M13966 Ref. Std. Dwg. GD-M13966
Figure 3.5 Typical Rise/Run Combinations for
Stair Slopes 30° to 40°
(Recommended Tread Run + Rise = 17 1/2")

Fed-OSHA 1910.24
E. DOORS AND LANDINGS FOR ACCESS/EGRESS OF
BUILDINGS (INCL. PORTABLE BUILDINGS FOR
OFFICE USE)
Chevron Guidelines
1. See Section 3.3 A for guidelines for stair slopes and di-
mensions for risers and treads.
2. Stairway landings at outwardly swinging doors should
have a minimum 30 x 30 inch landing area which is clear
of the swing of the door. In some jurisdictions, the land-
ing shall have minimum length of 5 feet 0 inches.
3. Stairway landings shall be no more than 1 inch lower than
the threshold of the doorway (may be more stringent for
handicapped access - see Figure 9.4).
4. Railings shall be provided on open sides of stairs which
have four or more risers.
5. Stairways parallel to the building are preferred. See Fig-
ure 3.6 for details.
Fed-OSHA 1910.23
1. Where doors or gates open directly on a stairway,
a platform shall be provided, and the swing of the
door shall not reduce the effective width to less
than 20 inches.
Fed-OSHA 1910.37
Note: An exit or exit access door swinging into an aisle
or passageway shall not restrict the effective width
thereof at any point during its swing to less than the
minimum widths specified in 1910.37.
Cal-OSHA 3235
1. Width and height. Every required exit doorway
shall be of a size that permits the installation of a
door not less than 3 feet wide and
not less than 6 feet 8 inches high.
When installed in exit doorways, exit
doors shall be capable of opening at
least 90 degrees and shall be
mounted so that the clear width of
the exitway is no less than 32 inches.
In computing the exit width required,
the net dimension of the exitway shall
be used.
Figure 3.6 Landings at Outwardly Swinging Doors

Fed-OSHA 1910.24
Safety in Designs
F. CIRCUMFERENTIAL STAIRWAYS FOR
CYLINDRICAL TANKS
Chevron Guidelines
1. Circumferential stairs ascending clockwise are preferred.
A stair rail is also required between the tank and stairs if
the gap between the tank/tank insulation and stairs is
greater than 6 inches.*
2. All treads should be constructed from steel grating. See
Figure 3.7 for details.
3. SeeFigure 3.15for details of gaging platform for cone roof
tanks.
4. See Figures 3.16 through 3.19 for details of gaging plat-
form for floating roof tanks.
5. Intermediate landings are not required on circular stair-
ways.*
G. CIRCUMFERENTIAL STAIRWAYS FOR SPHERICAL
TANKS
Chevron Guidelines
1. All treads should be constructed from steel grating. See
Figures 3.2, 3.7, 3.8, and 3.9 for details.
2. Upper run of stairway may follow contour of tank.
3. Provide unobstructed 30 x 30 inchclear landing at base
of stairway.*
4. Intermediate platform is not required for circular stair-
ways. See Figure 3.10 for details.
Cal-OSHA 3214
1. Stairs that follow the contour of tanks or other cy-
lindrical structures where the construction requires
the inside clearance between the inside stair
stringer and wall or tank side to be 8 inches or
less, shall not be considered to be an “open side.”

Fed-OSHA 1910.24
Figure 3.7 Steel Stairway Details

Fed-OSHA 1910.24
Safety in Designs
Figure 3.8 Typical Circular Stair Ref. Std. Dwg. GF-D99639

Fed-OSHA 1910.24
Figure 3.10 Spherical Tank
Figure 3.9 Stair Tread Detail
(Modified for support from tank shell.) See Figure 3.8 for plan arrangement.

Fed-OSHA 1910.24
Safety in Designs
3.4 GENERAL REQUIREMENTS FOR STEEL
RAMPS, STILES, WALKWAYS AND
PLATFORMS
A. GENERAL REQUIREMENTS FOR RAMPS
Chevron Guidelines
1. 7° (1 to 8) is the maximum slope of ramps.
2. See Section 2.3A-2 for railing requirements. Note that in
California, when a guardrail is required, the height of
the top rail from the ramp is 42 inches. A handrail may
also be required depending on ramp slope.*
3. Exit ramps which have slopes greater than 3.5° (1 to 16)
require handrails, landings at top (5 feet long) and bot-
tom (6 feet long), and one intermediate landing (5 feet
long) for each 5 feet of rise.
B. STEEL RAMPS
1. Install L 1-1/2 x 1-1/2 x 1/4 inch under each joint be-
tween floor plates.
2. If bolted connections are required all holes shall be 9/16
inch for 1/2 inch bolts.
3. See Figure 3.11 for typical arrangement.
C. STEEL STILES
Chevron Guidelines
1. Length of stile walkway shall be not less than 30 inches
and shall not exceed 9 feet 6 inches (structural limit for
minimum loading - 75 psf live load) unless intermediate
supports are provided or a larger channel member is used.
Also structural limit for stair stringer plate is 6 risers maxi-
mum.
2. See Figure 3.12 for typical arrangement.
3. See Figure 3.14 for recommended walking surfaces.
4. Install L 1-1/2 x 1-1/2 x 1/4 inch under each joint be-
tween floor plates.
5. Width shall not be less that 30 inches.
6. Drill 1/2-inch diameter weep holes in floor plate where
necessary.
7. See Section 2.0 for guardrail and stair rail requirements.
CAL-OSHA 3233.
1. The slope of the ramp shall not exceed 1 vertical
to 8 horizontal, except ramps used for powered
industrial trucks shall not exceed 1 vertical to 3
horizontal.
2. Ramps more than 30 inches above the adjacent
ground or floor shall be provided with guardrails.
Guardrails shall be continuous from the top of the
ramp to the bottom of the ramp.
3. The surface of the ramp shall be roughened or
shall be non-slip material.

Fed-OSHA 1910.24
Figure 3.11 Steel Ramp

Fed-OSHA 1910.24
Safety in Designs
D. STEEL WALKWAYS AND PLATFORMS
Chevron Guidelines
1. See Figure 3.14 for recommended walking surfaces.
2. Where floor plate is used, drill 1/2-inch diameter weep
holes for drainage where necessary.
3. Walks or platforms not provided with railing (less than
30 inches high) shall have guardrail at any sharp change
of direction (L or T shaped), such stop railings being at
least as wide as the walkway.
4. The design load for walkways and platforms should be
the maximum probable loads produced by the intended
use. The design load shall be increased as necessary for
any machinery or equipment which may add to the live
load.
5. Steel plate with a non-skid coating is generally recom-
mended for walkway and platform surfaces (refer to
CRTC Civil and Structural Manual, Section 343). How-
ever, serrated steel grating or grip strut grating should be
used in the following situations:
Figure 3.12 Steel Stile
The requirement for uniform tread rise height (see Section 3.3-A) applies to rise from floor or lower
platform to first tread and rise from top tread to top platform. See Ref. Std. Dwg. GA-M1001 for single
riser stile.
Ref. Std. Dwg. GB-M1002

Fed-OSHA 1910.24
• platform where operating conditions make steel plate
with non-skid coating ineffective; such as areas where
liquid spillage is expected
• in wet and cold climates where precipitation and ice
commonly create walkway hazards
• for platforms, walks and stiles less than six feet from
grade
• for platforms where there is a need to “see through”
such as on furnace firing platforms and on plot limit
block valve manifolds
• for stair treads (see Figure 3.7 for design details)
6. Install L 1-1/2 x 1-1/2 x 1/4 inch under floor plate joints.
7. All holes shall be 11/16 inch for 5/8-inch bolts. See Fig-
Ref. Std. Form CIV-EF-632
Figure 3.13 Steel Walkways

Fed-OSHA 1910.24
Safety in Designs
E. STEEL SERRATED GRATING FOR WALKWAYS
AND PLATFORMS
Chevron Guidelines
1. Grating used in coastal areas should be galvanized; for
inland areas (non-corrosive atmospheres), steel grating
may be painted.
2. Some plants have special problems which may warrant
the use of aluminum or stainless steel grating, or the ap-
plication of special coatings to retard corrosion.
3. The use of pre-stressed concrete or fiberglass gratings re-
quires applicable design specifications from the appro-
priate engineering group. Fiberglass grating may be pro-
hibited. Also, see Section 1.5.
4. All cross bars shall be flush or lower than the bearing
bar. Some manufacturers of serrated steel grating cur-
rently allow a tolerance of plus or minus 1/16 inch be-
tween bearing bar and cross bar. Care must be taken when
ordering to insure an even or negative tolerance. The
following serrated gratings are presently acceptable for
use within the Company (Specification CIV-EG-398):
Metal Bar Grating
• IKG Borden Grating Type W/B
• Gary Type GW
• Blaw-Knox Electroforged
• Klemp KW-19-4
Expanded Metal Grating
• US Gypsum Serrated Grip Strut Grating
• US Gypsum Heavy Duty Grip Strut Safety Grating
See Figure 3.14 for details.
F. NON-PERMITTED WALKING SURFACES
Chevron Guidelines
1. Mechanically locked grating and non-serrated steel grat-
ing are not permitted for walking surfaces.
2. Checkered steel plate for use in stair treads is not permit-
ted. Checkered steel plate is not normally recommended,
but is acceptable where its common use has proven to be
reliable and safe and provided a non-skid coating is ap-
plied.

Fed-OSHA 1910.24
Figure 3.14 Types of Grating and Attachments
3.5 TYPICAL STEEL TANK GAGING PLATFORMS
A. CONE ROOF TANKS
Chevron Guidelines
2. A stair rail is also required between the tank and stairs if
greater than 6 inches (see Figure 3.15).
3. Provide 2 foot minimum clearance around gage and
sample hatches so gager can always work upwind of
hatch.
4. See Section 3.4 E for recommended walking surface.
5. All platform legs resting on tank roof shall be at tank roof
support locations or at adequately reinforced locations.

Fed-OSHA 1910.24
Safety in Designs
B. FLOATING ROOF TANKS
Chevron Guidelines
2. A stair rail is required between the tank and stairway if
greater than 6 inches.
3. Provide 2 foot minimum clearance around gage and
sample hatches so gager can always work upwind of
hatch (see Figure 3.16).
4. See Figure 3.14 for recommended walking surface.
5. Self-leveling treads are recommended for rolling ladders.
6. See Figures 3.17, 3.18, and 3.19 for details of tank plat-
forms, stairs and rolling ladder.
Ref. Std. Dwg. GF-D99639
Figure 3.15 Cone Roof Tank Gaging Platform

Fed-OSHA 1910.24
Figure 3.16 Floating Roof Tank Gaging Platform Ref. Std. Dwg. GF-D99639

Fed-OSHA 1910.24
Safety in Designs
Figure 3.17 Rolling Ladder Pivot Detail – Section A Ref. Std. Dwg. GF-D99639

Fed-OSHA 1910.24
Figure 3.18 Plan View of Platform and Circular Stairs at Wind Girder

Fed-OSHA 1910.24
Safety in Designs
Ref. Std. Dwg. GF-D99639
Figure 3.19 Gaging Platform – Elevation View

Fed-OSHA 1910.24
3.6 GENERAL REQUIREMENTS FOR WALKWAYS
AND PLATFORMS FOR TANKS
A. WALKWAYS AND PLATFORMS FOR VERTICAL
TANKS
Chevron Guidelines
1. Tank tops that are insulated must have independent plat-
forms and walkways or, where practical, side-of-tank plat-
forms.
2. Independent platforms and walkways are preferred for
all working and walking surfaces of tanks. However, tank
roofs on non-insulated tanks may be used for these pur-
poses if: the slope of the roof does not exceed 2 inches
per foot, a non-skid surface is applied to and properly
maintained on all working, walking surfaces, the tank
roof is properly reinforced for live load floor support, and
the tank content is non-corrosive material.
3. The walking surface shall be clearly defined by color con-
trast. The deck of the roof shall be at least 1/8-inch thick
and structurally capable of supporting maximum prob-
able live load and shall be inspected annually to assure
its structural integrity (see CRTC Loss Prevention Guide
No. 6).
4. In areas with significant snow, place stairway on shel-
tered side of tank if possible.
5. When two or more tanks are interconnected, a second
means of egress shall be provided if a potential hazard or
injurious chemical exposure can block access to the main
egress. Tanks in water or other service which present no
potential hazard exposure are exempt from this require-
ment. See Figure 3.20.
6. SeeFigures 3.21 and3.22 for details of walkways for tanks.
Cal-OSHA 6803
1. The roofs of tanks and reservoirs in service shall
be externally inspected by a qualified person at
intervals not to exceed one year. Where a roof
has been found to be unsafe or has not been
inspected, substantial barriers shall be erected
to block off the entire roof or that portion which is
unsafe. Legible signs shall be posted at all ap-
proaches to the tank or reservoir roof if the entire
roof is blocked off, or on the barrier facing all ap-
proaches to the defective area if only a portion of
the tank or reservoir roof is barricaded. These
signs shall read: “DANGER - UNSAFE ROOF -
KEEP OFF” or equivalent wording in letters at
least 2 inches in height.
2. Where the means of access, the walkways, or
the platforms of a group of two or more tanks are
connected, there shall be provided sufficient un-
obstructed stairways, ramps, fixed ladders,
slides, walkways or crosswalks to permit an em-
ployee to escape from the roof, walkway or plat-
form of any tank in the group in the event the
walkway or platform of any other tank in the group
becomes impassable due to fire or other emer-
gency. Provided, however, that this order shall
not apply to tanks containing water or tanks con-
taining petroleum products having an open cup
flash point above 300°F as determined by
A.S.T.M. Designation D92, or in the case of fuel
oils by the A.S.T.M. Designation D93, and where
such tanks are isolated from tanks, pipelines and
other equipment containing liquids at a tempera-
ture above 150°F, gases, flammable liquids or
corrosives.

Fed-OSHA 1910.24
Safety in Designs
Figure 3.20 Walkways for Tanks – Plan View

Fed-OSHA 1910.24
Figure 3.21 Walkways for Tanks – Elevation View

Fed-OSHA 1910.24
Safety in Designs
B. WALKWAYS FOR SMALL DIAMETER TANKS
Chevron Guidelines
1. Walkways should be designed for movement and settling
of tanks. See Figure 3.22 for details.
Figure 3.22 Walkway Arrangement for Small Tanks – Plan and Elevation

Fed-OSHA 1910.24
3.7 BOLTED STEEL STAIRWAYS AND WALKWAYS
A. GENERAL REQUIREMENTS FOR BOLTED
CONSTRUCTION
Chevron Guidelines
1. For some remote locations such as production tank batter-
ies, bolted stairways and walkways as defined in API, 12B
Standard may be used. However, if they are subject to wear
and tear of frequent use or to a severe or wet environment,
frequent maintenance may be necessary and their use may
not be appropriate. A safety engineer should be consulted
to determine applicability and suitability. See Figure 3.23.
B. DESIGN REQUIREMENTS FOR BOLTED
CONSTRUCTION
Chevron Guidelines
1. Railings are required to support 200 lbs. loading at any
point and in any direction on top railing.
2. Stair slope should be uniform within an area or location
and shall not exceed 45°.
3. Weather protection shall be provided. Galvanized parts
are generally recommended. Grating is preferred for stair
treads (see Figure 3.14 for details).
Figure 3.23 Typical Bolted Stairway and Walkway Construction

Fed-OSHA 1910.24
Safety in Designs
3.8 REQUIREMENTS FOR WOOD CONSTRUCTION
A. GENERAL REQUIREMENTS FOR THE USE
OF WOOD
Chevron Guidelines
1. See Section 1.5 for requirements when using wood.
B. GENERAL REQUIREMENTS FOR WOOD STILES
1. Use only galvanized nails:
• Treads to stringer: 3 - 20d nails each end
• Cleats to stringer: 5 - 20d nails each end
• Plank to brace: 3 - 20d nails each end
• Stringer to plank: 3 - 20d nails each side
2. Treads and planks shall be rough cut.
3. Baseboards shall be treated Douglas fir or equal. All other
lumber shall be construction grade Douglas fir, or equal,
and surfaced 4 sides (S4S).
4. The wooden stile shown in Figure 3.24 is designed for 75
PSF live load (acceptable for light duty use only). Struc-
tural limit for stair stringer is 3 risers maximum.
Figure 3.24 Wooden Stile

Fed-OSHA 1910.24
Figure 3.25 Wooden Stairway
C. GENERAL REQUIREMENTS FOR WOOD
STAIRWAYS
Chevron Guidelines
1. See Figure 3.4 and Figure 3.5 for general requirements for
stair slope, tread run, and rise dimensions.
2. Baseboard sill shall be treated Douglas fir or equal.
3. All other lumber shall be construction grade Douglas fir
or equal and surfaced 4 sides (S4S), except treads to be
rough.
4. For bolted construction use 5/8-inch galvanized carriage
bolts with steel cut washers and two nuts.
5. For nailed construction use only galvanized nails:
• Cleat to stringer: 5-8d nails (min.)
• Tread to stringer: 3-20d nails each end (min.)
6. Stairways shall be built to carry a load of five times nor-
mal anticipated live load but not less than a 1000 pound
moving concentrated load. See Figure 3.25 for details.

Fed-OSHA 1910.24
Safety in Designs
D. GENERAL REQUIREMENTS FOR WOOD RAMPS
Chevron Guidelines
1. 7° (1 to 8) is the maximum slope of ramps.
2. All lumber shall be construction grade Douglas fir, or
equal. Top rail shall be surfaced 4 sides (S4S).*
3. See Section 2.2 for railing requirements. Note that ramps
may require both guardrail and handrail.
4. The wooden ramp in Figure 3.26 is designed for 75 PSF
live load (acceptable for light duty use only).
5. Ramps used for exits that have slopes greater than 3.5° (1
to 16) require a handrail, landings at top (5 feet long),
and bottom (6 feet long), and one intermediate landing
for each 5 feet of rise.
6. All nails shall be galvanized:
• Cleat to plank: 3 - 8d nails each plank
• Plank to support: 3 - 20d nails each plank
Figure 3.26 Wooden Ramp

Fed-OSHA 1910.24
E. GENERAL REQUIREMENTS FOR WOOD WALKWAYS
Chevron Guidelines
1. All planking shall be construction grade Douglas fir,
rough cut. Top rail shall be surfaced 4 sides (S4S).*
2. Walks or platforms not provided with handrails (less than
30 inches high) shall have stop railings at any sharp
change of direction (L or T shaped), such railings being
at least as wide as the walkway.
3. The wooden walkway below is designed for 75 pounds
per square foot live load (acceptable for use in light duty
applications only). See Figure 3.27 for details.
Suggested Fabrication Detail
4. All nails to be galvanized:
• Cleat to plank: 5 - 8d nails each plank
• Plank to stringer joist: 5 - 20d nails each end
5. For bolting use 5/8-inch galvanized machine bolts with
steel cut washers.
Figure 3.27 Wooden Walkway

Fed-OSHA 1910.24
Safety in Designs
Fed-OSHA 1910.24
OTHER GUIDES
24 Cal Code of Regs. 2-3305 & 3306 State Building Code
“Stairways” and “Ramps”
Uniform Building Code Section 3306
“Stairways”
A64.1-1968 USA Standard
“Requirements for Fixed Industrial Stairs”
API Standard Spec. 12B
“Specification for Bolted Tanks for Storage of Production
Liquids”
Chevron Corporation Loss Prevention Guide No. 6
“Accessing Tank Roofs”
CRTC Civil and Structural Manual
Section 300
CRTC Engineering Standards:
Form CIV-EF-632 - “Low Walks”
Drawing GA-M1001 - “Standard Stile, Type 1”
Drawing GB-M1002 - “Standard Stile, Type 2”
Drawing GD-M13966 - “Standard Steel Stairs”
Drawing GF-D99639 - “Circumferential Stairways and
Platforms for Tanks”
Drawing GF-M99931 - “Platforms for Vertical Vessels”
Specification CIV-EG-398 - “Steel Fabrication”

Fed-OSHA 1910.27
Section 4 • Ladders
4.0 LADDERS
This section provides guidance for the design, and use of fixed lad-
ders. Designs for both steel and wood construction are included in
this section. Steel construction is preferred and should be consid-
ered first. Use of wood should be minimized. See Section 1.5 of this
manual for additional guidelines.
4.2 All Fixed Ladders ...................................................................................... 2
4.3 Steel Fixed Ladders .................................................................................. 4
4.4 Fall Protection Features........................................................................... 9
4.5 Wooden Fixed Ladders........................................................................... 13

Fed-OSHA 1910.27
Safety in Designs
4.2 ALL FIXED LADDERS
A. GENERAL REQUIREMENTS FOR ALL FIXED LADDERS
Chevron Guidelines
1. Fixed ladders may be used for access to elevated tanks,
towers, and similar structures, overhead traveling cranes,
etc., where the use of fixed ladders is common practice.
(See Figure 4.1 for summary.)
2. Fixed ladders may be used for secondary access, escapes,
maintenance access to platforms or other access which
are used infrequently or where stairways are impractical
(See Section 3.2 A).
3. The design load shall be determined by the anticipated
usage of the ladder, but not less than a single concen-
trated live load of 200 lbs.
4. The weight of the ladder and attached appurtenances to-
gether with the live load shall be considered in the de-
sign of rails and fastenings.
5. Fixed ladders may not be used as a substitute where stair-
ways are required. (See Section 3.2 A.)
6. Slide poles are not acceptable.
7. Ladders should be vertical whenever possible. Where
clearance problems require the ladder to be sloped, the
slope shall not exceed 15° forward and shall not slope
backward under any circumstances. Fixed ladders shall
be straight throughout their length.
8. Ladders should be oriented so that a person faces the
structure or vessel while climbing. Side access ladders
are preferred to the front access style.
1. The minimum design live load shall be a single
concentrated load of 200 lbs.
2. The weight of the ladder and attached appurte-
nances together with the live load shall be consid-
ered in the design of rails and fasteneings.
3. The number and position of additional concen-
trated live-load units of 200 lbs. each as deter-
mined from anticipated usage of the ladder shall
be considered in the design.
4. The minimum clear length of rungs or cleats shall
be 16 inches.
5. Rungs and cleats shall be free of splinters, sharp
edges, burrs or projections which may be a haz-
ard.
6. Side rails which might be used as a climbing aid
shall be of such cross sections as to afford ad-
equate gripping surface without sharp edges, splin-
ters, or burs.
7. The perpendicular distance on the climbing side
of the ladder from the centerline of the rungs to
the nearest permanent fixed object shall be 30
inches for a ladder with a pitch of 90°.
8. The perpendicular distance on the back side of
the ladder from the centerline of the rungs to the
nearest permanent fixed object shall be 7 inches,
except when unavoidable obstructions are en-
countered.
9. The step across distance from the nearest edge
of the ladder to the nearest edge of equipment or
structure shall not be more than 12 inches or less
than 2-1/2 inches.
Figure 4.1 Ladder Requirement Summary
NOTE: The requirements for drop bar, hoop guard, cage, and offset rest platform are applicable to both steel
and wooden ladders in general use. However, special use ladders and emergency only use ladders may have
alternate requirements. Refer to applicable code and regulation or consult with safety engineer.
PLATFORM HEIGHT STEEL STRINGER SIZE DROP BAR HOOP CAGE
2 x 1/2 2-1/2 x 1/2 GUARD
1. Less than 30" Required
2. 30" or greater and less than 10' Required Required
3. 10' or greater and less than 12' Required Required Required
4. 12' or greater and less than 20' Required Required Required
5. 20' or greater and up to 30' Required Required Required Required
6. NOTE: Long ladders require rest
platforms every 30 feet.
Not acceptable for typical plant use. Use offset sections with rest
platforms.

Fed-OSHA 1910.27
10. A clear width of at least 15 inches shall be pro-
vided each way from the centerline of the ladder
in the climbing space.
11. One rung of the ladder shall be located at the
level of the landing laterally served by the land-
ing.
12 Ladder rungs shall be equally spaced through-
out including the first rung below the landing.
13. Ladder extensions shall extend 3 1/2 feet (42
inches) above parapets and landings.
14. Clearance between rails on step through ladders
shall not be less than 18 inches nor more than
24 inches.
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Chevron adopted a 30 inch clearance prior to the
OSHA Standard. The 30 inch clearance is con-
sistant with ANSI A 14.3.
15. For side-step or off-set ladder sections, the side
rails and rungs shall be carried to the next regu-
lar rung beyond or above the 3 1/2 foot (42 inch)
minimum.
Cal-OSHA 3277
1. The vertical distance of the first rung from ground
level may be as high as 14 inches.
Fed-OSHA 1910.24
Figure 4.2 Clearance for Unavoidable
Obstructions at Rear of Fixed Ladders.
9. Ladder rungs, side rails, and supports shall be free of
splinters, sharp edges, burrs, and projections.
10. Ladder width:
• 16 inches minimum width between rails (stringers).
11. Landings:
• 30 x 30 inch minimum landing area is required for
the base of ladders. This clear area shall extend ver-
tically through the climbing space, except when
cages are installed.*
• Landing area with minimum opening of 30 inches
and minimum length of 30 inches measured at the
centerline of the opening is also required at top of
ladders or offset platforms.
• (Coordinate layout of landings for ladders during
foundation design to avoid interferences.)
12. Clearances:
• 7 inches minimum clearance behind the ladder rung
centerline is required throughout the length of the
ladder. Common problems are conduit, stiffening
rings, foundations, field routed small piping, etc.
• Exceptions: The edge of top landing is not included
in this requirement (see Figure 4.6). Unavoidable
structural members may infringe upon this clearance
if confined as shown in Figure 4.2.*
13. Rung Spacing:
• Rung spacing shall be 12 inches
center to center and shall be uni-
formly spaced throughout the
length of the ladder.
• The height between the bottom
rung and grade may be 6 to 18
inches.
Note: Max. 14 inches allowed in
California.
14. Ladder Guard:
• A barrier should be placed on the
back side of ladders that can be in-
advertently climbed on the wrong
side.
15. Platform Rung:
• One rung of the ladder shall be lo-
cated at the level of the platform
landing.
16. See Figure 4.1, “Ladder Requirement
Summary”, for cages, hoop guards,
and drop bars requirements.
17. Refer to Section 1.4 B, “Conditions
Which Require Secondary Egress from
Industrial Buildings and Structures.”*

Fed-OSHA 1910.27
Safety in Designs
B. REQUIREMENTS FOR LADDERS IN WELLS
1. Ladder wells shall have a clear width of 15 inches mea-
sured each way from the centerline of the ladder.
2. There shall be a 30 inch minimum clear distance on the
climbing side of the ladder to fixed objects.*
4.3 STEEL FIXED LADDERS
A. SPECIFIC REQUIREMENTS FOR STEEL FIXED
LADDERS
Chevron Guidelines
1. Platforms which access the same ladder flight should be
separated by 2 feet minimum elevation change. See Fig-
2. For details of ladder heads, see Figures 4.5 and 4.6.
3. For details and comments of hoop guards and drop bars,
see Section 4.4.
4. Ladder feet may be braced at landing or to the structure
or equipment. (See Std. Dwg. GF-M88575.)*
5. Fabricate ladder 12 inches longer at base than anticipated
length required. Trim base at installation.*
1. Ladder wells shall have a clear width of 15 inches
measured each way from the centerline of the
ladder.
2. Smooth-walled wells shall be a minimum of 27
inches from the centerline of the rungs to the well
wall on the climbing side of the ladder. There
shall be a minimum of 30 inches on the climbing
side where other obstructions on the climbing side
exist.
Note: See general OSHArequirements in Section 4.2.
1. All rungs shall have a minimum diameter of 3/4
inch, except when protection of deterioration is
required.

Fed-OSHA 1910.27
Ref. Std. Dwg. GF-M88575
Figure 4.3 Fixed Steel Ladder

Fed-OSHA 1910.27
Safety in Designs
Figure 4.4 Individual Rung Ladder
B. INDIVIDUAL RUNG LADDERS
Chevron Guidelines
1. See Chevron Guidelines in Section 4.2 and Figure 4.4.
2. Ladder rungs should be made of steel, protected from
corrosion, and made non-slip.
3. The design load shall be determined by the anticipated
usage, but not less than a single concentrated live load of
300 lbs.
4. Rungs welded to side of columns and towers are similar.
The ends of each rung welded to the supporting struc-
ture shall be designed to support the maximum load on
the rung.
Note: See general OSHA requirements in Section 4.2.
1. The rungs of an individual-rung ladder shall be
so designed that the foot cannot slide off the end.

Fed-OSHA 1910.27
Figure 4.5 Side Access Ladder Head (Preferred Arrangement)
C. SIDE ACCESS LADDER HEADS
Chevron Guidelines
1. The side access ladder head is preferred where structure
or equipment is available for supporting ladder string-
ers directly.
2. Figure 4.5 shows the side access arrangement.

Fed-OSHA 1910.27
Safety in Designs
Figure 4.6 Step Through Ladder Head (Alternate)
D. STEP THROUGH LADDER HEADS
Chevron Guidelines
1. Figure 4.6 shows the step through arrangement.

Fed-OSHA 1910.27
4.4 FALL PROTECTION FEATURES
A. HOOP GUARDS AND DROP BARS
Chevron Guidelines
1. Hoop guards shown inFigure 4.7 are required for all fixed
ladders serving elevations 10 feet or more above the
ground, existing platform or floor.
2. All fixed ladders serving elevations 30 inches or more
above ground, platform, or floor level shall be equipped
with drop bars attached as follows:
• Side access ladders hinge at the ladder side.
• Front access ladders hinge at the right when facing
the ladder from the platform side.
Drop bars shall not be placed beyond the outer edge of
the platform.
3. Figure 4.7 and Figure 4.8 shows the typical arrangement
for hoop guards and drop bars.
Fed-OSHA 1910.23
Figure 4.8 Drop Bar Details
1. Every ladderway floor opening or platform shall
be guarded by a standard railing with standard
toeboard on all exposed sides (except at entrance
to opening), with the passage through the railing
either provided with a swinging gate or so offset
that a person cannot walk directly into the open-
ing.
Chevron adopted a drop bar prior to Fed. OSHA
requirement.The drop bar provides equivalent pro-
tection.
Figure 4.7 Hoop Guards and Drop Bars
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Fed-OSHA 1910.27
Safety in Designs
B. LADDER CAGES
Chevron Guidelines
1. All fixed laddersserving elevations 20 feet or moreabove
grade shall be equipped with ladder cages.*
Exceptions:
• ladders on mobile equipment where such devices in-
terfere with mobility of equipment
• ladders on smokestacks, water towers, transmission
poles that are used by steeple jacks or riggers, etc.,
for occasional maintenance and where such persons
are required to use safety belts or approved ladder
climbing device
• ladders less than 20 feet in length, originating from
large platforms, such as 10 x 10 feet, located at eleva-
tions 20 feet or more above grade*
2. Unless protected by location, a barrier or additional
straps are required where the base of the ladder is less
than 4 feet from the platform edge when the platform is
greater than 20 feet above floor or grade level.*
3. Figure 4.9 shows typical ladder cage arrangement.
1. Cages or wells shall be provided on ladders of
more than 20 feet and a maximum unbroken length
of 30 feet.
OSHA Interpretation
The requirements of 1910.27 for cages, platforms
or similar fall protection devices are not appro-
priate for fixed ladders on structures where the
fixed ladders are used only as a means of ac-
cess for firefighters and other emergency per-
sonnel, or escape for employees in fire and other
emergency situations. In such cases, the em-
ployer must establish and implement adequate
administrative controls such as barricades and
signs to prevent non-emergency use of fixed lad-
ders which are meant for fire fighter and emer-
gency escape only. [Fed-OSHA Instruction Std
1-1.12, (6-20-83)]
2. Cages shall extend a minimum of 42 inches
above the top of the landing, unless other ac-
ceptable protection is provided.
3. 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 a bottom flare of not
less than 4 inches, or portion of the cage oppo-
site the ladder shall be carried to the base of the
ladder.
4. Cages shall not extend less than 27 inches nor
more than 28 inches from the centerline of the
rungs of the ladder. Cages shall not be less than
27 inches in width.
Chevron adopted a 30 inch clearance prior to the
OSHA Standard. The 30 inch clearance provides
additional space for workers wearing self-con-
tained breathing apparatus.The 30 inch clearance
is consistant with ANSI A 14.3.
5. The inside of cages shall be clear of projections.
6. Vertical bars shall be located at a maximum spac-
ing of 40° around the circumference of the cage.
This will give a maximum spacing of 9-1/2 inches
center to center.
Due to Chevron's 30 inch cage clearance, bar
spacing of 32° is required to achieve 9-1/2 inch
maximum center to center spacing of vertical bars.
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Fed-OSHA 1910.27
Figure 4.9 Ladder Cages

Fed-OSHA 1910.27
Safety in Designs
Figure 4.10 Offset Fixed Ladder Sections
C. REST PLATFORMS FOR LADDERS
Chevron Guidelines
1. Long ladders shall be built in offset sections with rest
platforms every 30 feet maximum. Where possible plat-
forms should be located so the ladder flights are equal or
located so that the shortest flight is at the highest eleva-
tion.
2. The minimum dimensions of ladder landings on rest plat-
forms are 30 inches wide and 30 inches long.
3. Rest platforms shall be enclosed by standard railing and
toeboard on open sides.
4. Figure 4.10 shows typical ladder rest platform arrange-
ment.
1. When ladders are used to ascend to heights ex-
ceeding 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 sec-
tion shall be offset from adjacent sections. Where
installation conditions (even for a short, unbro-
ken length) require that adjacent sections be off-
set, landing platforms shall be provided at each
offset.
2. All landing platforms shall be equipped with stan-
dard railings and toeboards.
3. Landing platforms shall be not less than 24 inches
in width and 30 inches in length.

Fed-OSHA 1910.27
Figure 4.11 Wooden Ladder
1. All rungs shall have a minimum diameter of 1-1/8
inches.
2. When used under conditions where decay may
occur:
• wood ladders shall be treated with a non-irritat-
ing preservative, and
• the detail shall be such as to prevent or mini-
mize the accumulation of water on wood parts.
Note: The design stresses for wood components of lad-
ders shall not exceed those specified in 1910.25. All
wood parts shall meet the requirements of 1910.25 (b).
Note: See Section 4.2 for general OSHArequirements.
4.5 WOODEN FIXED LADDERS
A. SPECIFIC REQUIREMENTS FOR WOODEN
FIXED LADDERS
1. Galvanized nails or machine bolts with steel cut washers
shall be used.
2. Drive nails into ends of rungs to insure snug fit in string-
ers.
3. Figure 4.11 shows typical wooden ladder arrangement.

Fed-OSHA 1910.27
Safety in Designs
OTHER GUIDES
A 14.3-1992 ANSI Standard
“Ladders-Fixed- Safety Requirements”
CRTC Engineering Standard Drawing GF-M88575
“Standard Ladder Cages and Guards”

Fed-OSHA 1910.219
Section 5 • Guards: Mechanical, Hot Surface,
and Chemical Spray
5.0 GUARDS: MECHANICAL, HOT
SURFACE, AND CHEMICAL SPRAY
This section provides guidance for the design, and use of machinery
guards. Designs for both steel and wood construction are included
in this section. Steel construction is preferred and should be consid-
ered first. Use of wood should be minimized. See Section 1.5 for
additional guidelines.
5.2 General and Design Requirements for Machinery Guards............... 2
5.3 Approved Materials for Guards .............................................................. 4
5.4 Guarding for Conveyors and Related Equipment ................................ 7
5.5 Typical Fabrication Arrangements for Guards .................................... 7
5.6 Pumping Unit Guards.............................................................................. 16
5.7 Requirements for Abrasive Wheel Guards......................................... 20
5.8 Protecting Personnel from Hot or Cold Surfaces .............................. 21
5.9 Protecting Personnel from Chemical Sprays ..................................... 23
5.10Notes and References ............................................................................ 25
NOTE: An asterisk (*) after a section of text indicates that the informa-
tion in that section is new or revised as of September 1996.

Fed-OSHA 1910.219
Safety in Designs
5.2 GENERAL AND DESIGN REQUIREMENTS FOR
MACHINERY GUARDS
A. CONDITIONS WHICH REQUIRE GUARDING OF
EXPOSED PARTS
Chevron Guidelines
1. All moving parts of machinery that could cause injury if
inadvertently contacted by personnel and that are not
guarded by equipment or by location shall be guarded if
located within 7 feet 0 inches vertical height of floors,
stairways or platforms and within 15 inches horizontal
distance of floors, platforms, walkways, stairs, or ladders.
2. Some moving parts may require guarding even though
located greater than 7 feet 0 inches vertical height or
greater than 15 inches horizontal distance because of haz-
ards when failure occurs - such as a broken drive chain
or belt which may fall onto platform or walkway.
3. Typical hazardous moving parts are:
• rotating equipment such as shafts, pulleys, gears, cou-
plings, and flywheels
• reciprocating equipment such as pistons and connect-
ing rods
• conveyor belts and drive chains
• in-running rolls and screws
1. Flywheels:
Flywheels located so that any part is 7 feet or less
above the floor or platform shall be guarded as
follows:
• With an enclosure of sheet, perforated, or ex-
panded metal, or woven wire.
• With guard rails placed between 15 - 20 inches
from the rim.
- When the flywheel extends into a pit or is
within 12 inches of the floor, a standard
toeboard shall also be provided.
- When the upper rim of a flywheel protrudes
through a working floor, it shall be entirely
enclosed or surrounded by a guardrail and
toeboard.
Note: For flywheels with smooth rims 5 feet or
less in diameter, see 1910.219 (b) (iv).
2. Whenever flywheels are located above working
areas, guards shall be installed having sufficient
strength to hold the weight of the flywheel in the
event of a shaft or wheel mounting failure.
3. Cranks and Connecting Rod:
When exposed to contact, cranks and connecting
rods shall be meet the general requirements for
“Standard Guards”.
Note: See Section 5.2 B.
4. Horizontal Shafting:
• All exposed parts of horizontal shafting 7 feet
or less from floor or working platform shall be
protected by a stationary casing enclosing
shafting completely or by a trough enclosing
sides and top or sides and bottom of shafting
as location requires.
Note: See Chevron Interpretation below.
• Shafting under bench machines shall be en-
closed by a stationary casing, or by a trough at
sides and bottom as location requires. The
sides of the trough shall come within 6 inches
of the underside of the table, or if the shafting
is near the floor, within 6 feet of the floor. In
every case the sides of the trough shall extend
at least 2 inches beyond the shafting or protu-
berance.
The sides of the trough protecting horizontal shaft-
ing shall come within 6 inches of the floor or foun-
dation. In every case the sides of the trough shall
extend at least 2 inches beyond the shafting or
protuberance.
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Fed-OSHA 1910.219
and Chemical Spray
5. Shaft Ends:
Projecting shaft ends shall present a smooth edge
and end and shall not project more than 1/2 the
diameter of the shaft unless guarded by non-ro-
tating caps or safety sleeves.
6. Pulleys:
Note: Any parts of pulleys which are 7 feet or
less from the floor or working platform shall be
guarded in accordance with 1910.219 (d).
7. Horizontal belts, ropes and chain drives:
• Overhead horizontal belts with lower parts 7
feet or less from the floor or platform shall
be guarded on the sides and bottom per
1910.219 (o)(3). Under certain conditions, over-
head belts must be guarded for their entire
length.
Note: See 1910.218(e)(2).
• Where both runs of horizontal belts are 7 feet
or less from the floor level, the guard must ex-
tend at least 15 inches above the belt, except
where both runs of belt are 42 inches or less
from the floor, the belt shall be fully enclosed.
8. Gears, sprockets, and chains, unless they are
more than 7 feet above the floor or work platform,
shall be guarded in accordance with one of the
following:
• By a complete enclosure
• By a standard guard
• By a band guard
Note: See 1910.219 (f)(1).
9. Keys, setscrews, and other projections:
• Such projections in revolving parts shall be re-
moved or made flush or be guarded by metal
covers.
Note: See exceptions in 1910.219 (h)(1).
10. Collars and Couplings:
All revolving collars, including split collars, shall
be cylindrical, and screws or bolts used in collars
shall not project beyond the largest periphery of
the collar.
Shaft couplings shall be constructed so as to
present no hazard from bolts, nuts, setscrews or
revolving surfaces. Bolts, nuts, setscrews are
permitted where they are covered with safety
sleeves or where they are used in parallel with the
shafting and are countersunk or else do not ex-
tend beyond the flange or the coupling.
11. Openings for oiling of gears, sprockets and chains:
Note: See 1910.219 (f)(4) for requirements for
guard openings for the purpose of oiling moving
parts.

Fed-OSHA 1910.219
Safety in Designs
1. Materials for guards shall be expanded metal,
perforated or solid sheet metal, wire mesh on a
frame of angle iron, or iron pipe securely fastened
to the floor or frame of machine. All metal should
be free from burrs.
2. Expanded metal, perforated or solid sheet metal
and wire mesh shall be securely fastened to
frame.
Cal-OSHA 3944
1. Where a guard or enclosure is within 2 - 4 inches
of moving parts, openings through the guard shall
be of such size as will preclude the passage of
any object 1/2 inch in diameter.
2. Where a guard or enclosure is within 4 - 15 inches
of moving parts, the maximum opening shall be of
such size as will preclude the passage of any ob-
ject greater than 2 inches in diameter. Where slat-
ted guard is used, the width of the opening shall
be not greater than 1 inch.
Cal-OSHA 3945
1. Where lubrication must be performed while the
machine is operating, openings with hinged or slid-
ing covers shall be provided.
2. Where machines or machine parts must be lubri-
cated while in motion the lubricant fittings shall be
located at least 12 inches from the dangerous
moving parts unless such parts are guarded and
the fittings are piped outside the guard.
B. DESIGN REQUIREMENTS FOR STANDARD
GUARDS
Chevron Guidelines
1. Design requirements for guards are as follows. Guards:
• shall be built according to recognized standards of
construction and performance
• shall not create a hazard of their own (free of sharp
edges and burrs and not a bumping or tripping haz-
ard)
• shall be securely fastened and sturdy enough to sup-
port impact load of personnel falling against guard,
• should contain hazard resulting from failure of any
moving part
• shall not interfere with the operation of equipment
or machinery
• should minimize need for removal of guard for rou-
tine inspection and lubrication or should be supplied
with removable, sliding, or hinged sections for rou-
tine maintenance or inspection
2. Where machinery or equipment is lubricated while in
motion, lubrication fittings shall be stationary and ex-
tended a minimum of 12 inches from the moving parts
or extended outside of the guard.
5.3 APPROVED MATERIALS FOR GUARDS
A. METAL GUARDS
Chevron Guidelines
1. Acceptable guard materials are specified in Figure 5.1.
2. Acceptable fastening methods are specified in
Figure 5.2.
3. Materials for framework of guards shall be metal angle 1
x 1 x 1/8 inch, 3/8 inch solid metal rod, or metal con-
struction of equivalent strength. Guards of woven wire
or expanded metal in a frame with a total area of more
than 6 square feet shall have additional reinforcement.
4. Guards shall have rigid braces every 36 inches maximum
spacing to a fixed part of the machinery or building struc-
ture. Where the guard may contact moving equipment,
additional strength or reinforcement may be required.
1. Metal Guards.
All guards shall be rigidly braced every 36 inches
or fractional part of their height to some fixed part
of machinery or building structure.
Note: Guards for overhead belts must comply with the
requirements of 1910.12219 (o)(3).

Fed-OSHA 1910.219
and Chemical Spray
5. The framework of guards fastened only to the floor or
working platform shall consist of 1-1/2 x 1-1/2 x 1/8 inch
metal angle, 1-1/2 inch outside diameter metal pipe or
metal construction of equivalent strength. The frame-
work shall be rigid for all probable loading conditions.
6. Rectangular guards shall have minimum 4 upright frame
members which shall be securely fastened to fixed equip-
ment or floor. Cylindrical guards shall have a minimum
3 supporting members which shall be securely fastened
to fixed equipment or floor.
Figure 5.1 Guard Filler Material
Other material may be used if equivalent strength and protection are
provided. Stronger and heavier gauge material may be required for vibra-
tion, chemical attack, or other exceptional stress. Wood guards shall not be
used except where the presence of fumes or other manufacturing condi-
tions would cause rapid deterioration of metal guards or where extreme
heat or cold would make metal guards undesirable.

Fed-OSHA 1910.219
Safety in Designs
Figure 5.2 Methods of Fastening Filler to Frame
The filler may be fastened to framework by:
• rivets or bolts spaced not more than 5 inches center to center;
• welding spaced not more than 4 inches center to center;
• weaving through angle frame or pipe; or
• bending entirely around rod frames (if filler material is 14 gauge or heavier).

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