standard de praxair segÚn norma osha

PRAXAIR STANDARD S-1

ISSUE DATE 12/15/63REVISION DATE 2/12/03

EFFECTIVE DATE 2/27/03WRITTEN BY F. J. Clay

PRAXAIR, INC. REVISED BY R. CritelliPRAXAIR TECHNOLOGY CENTER APPROVED BY E. N. SaccocciaTONAWANDA, NY 14151-0044 RELEASED BY J. P. Bernard

FOR USE ONLY IN CONJUNCTION WITH THE PROPOSAL,ORDER OR CONTRACT OF WHICH THIS IS A PART of 34

SPECIFICATIONS FOR DESIGN OF LADDERS, STAIRWAYS,RAILINGS, AND PLATFORMS

1.0 SCOPE

This Standard defines the minimum requirements and best practices for the selection,design and construction of fixed ladders, stairways, rails and platforms in Praxair facilities.Requirements related to floor and wall openings and tops of domed structures requiring access areincluded.

This Standard is based on United States Occupational Safety and Health Administration(OSHA) requirements for non-construction ladders, 29 CFR 1910.21 through .27, which have beenadopted in many parts of the world in one form or another. It is not intended for this Standard to beconsistent with OSHA 29 CFR 1926, Construction Regulations.

2.0 TABLE OF CONTENTS

Tables Page

1 Fixed Metal Ladders 4

2 Fixed Stairways 9

3 Railings 11

4 Platforms 14

5 Floor and Wall Openings 16

6 Top of Domed Structures Requiring Access 18

Figures:

Note: Figures referenced in the tables are shown with the generic figure number only (i.e.,Fig. 1). The user shall determine the appropriate English or metric reference (i.e., Fig 1E or Fig.1M).

Praxair Standard S-1 (Rev. 2/12/03)


English Units Metric Units Component Page E/M

1E 1M Ladders 19 / 27



4E 4M Stairways 22 / 30

5E 5M Stairways 23 / 31

6E 6M Handrailings 24 / 32

7E 7M Handrailings 25 / 33

8E 8M Individual Rung Ladders 26 / 34

9E 9M Pitch of Fixed Ladders 26 / 34

10E 10M Open Clearance in Grating 26 / 34

11E 11M Grating Spacing 26 / 34

12E 12M Platform Clearance for Equipment 26 / 34

13E 13M Door Swing into Elevated Platform 26 / 34

3.0 GENERAL

Whenever this Standard deviates from local codes or regulations, the local codes orregulations shall have precedence if they are more stringent.

Except where required by this Standard, ladders, platforms and stairways should be locatedso as to minimize or eliminate the use of temporary structures in the performance of routine tasks.Examples of routine tasks include, but may not be limited to, the reading of local gauges and thefrequent manual adjustments of valves for process control. Final decisions related to these struc-tures should have the understanding and acceptance of the operating group or external customerthat will have accountability for plant operation.

4.0 REFERENCES

1) Local, state, federal, country, building, and fire marshal codes, etc.

Note: Civil Design Engineering has steel fabrication details available in the CivilDesign Engineering directory: \\tonsrv1\ACAD2\Standards\Details\Civil\05_Metal_Steel

These AutoCAD standard details are for ladders, stairways, handrails, andplatforms and are available upon request. “tonsrv1” is the GSS AutoCAD file



server located in Tonawanda, NY. For directory access instructions, contact yourlocal network administrator.

2) Praxair Standard GS-32 – Cooling Tower Specification

3) Praxair Standard GS-91 – Truck Scale Specification

4) ASCE 7 Minimum Design Loads for Buildings and Other Structures

5) International Building Code 2000

6) Uniform/National/Standard Building Codes – through 1999

7) U. S. Code of Federal Regulations, title 29, part 1910, subpart D – Walking-WorkingSurfaces (sections 1910.21 through 1910.27)



Table 1Fixed Metal Ladders

Item Design Requirements (Reference OSHA 1910.27 except where noted)

1.1 DESIGN REQUIREMENTS:1.1.1 Design

Considerations• Minimum design live load shall be a single concentrated load of 300

pounds (136 kg). (ASCE) (See Fig. 1)• The number and position of additional concentrated live load units of

300 pounds (136 kg) each as determined from anticipated usage of theladder shall be considered. (Praxair)

• The live load imposed by persons shall be considered to beconcentrated at such points as will cause the maximum stress.

• The weight of the ladder and attached appurtenances together with thelive load shall be considered in the design of rails and fastenings.

• The maximum allowable uninterrupted ladder length between landingsshall not be greater than 30 feet (9144 mm). Personnel must be forcedto step off a ladder onto a working or rest platform before climbingmore than 30 feet (9144 mm).

1.2 SPECIFIC FEATURES:1.2.1 Rungs and Cleats • Minimum diameter of 3/4 inch (20 mm) for metal and 1-1/8 inch (30

mm) for wood. Ladders rungs imbedded in concrete shall have aminimum diameter of 1 inch (25 mm) or shall be painted or otherwisetreated to resist corrosion and rusting. (Fig. 1)

• Spacing of rungs shall not exceed 12 inches (305 mm) and shall beuniform throughout the length. (Fig. 1)

• Minimum clear length is 18 inches (460 mm). (Praxair)• Free of splinters, sharp edges, burrs, or projections.• Individual rungs (without side rails, example cast in concrete or welded

to casing) shall be designed so the foot cannot slide off the side end(make down loop depression or equal). (Fig. 8)

• ¾ inch (20 mm) or larger square bars turned on edge are not acceptable.(Praxair)

• Note that rungs are not required to be designed or treated to minimizeslipping as specified in 29 CFR 1926.1053 (construction use ladders).

1.2.2 Side Rails • Might be used as a climbing aid and shall be of such cross sections as toafford adequate gripping surface without sharp edges, splinters, orburrs.

• The minimum side rails shall be channels C3x4.1 or member of equalstrength. (Fig. 1) (Praxair)

1.2.3 Fastenings(Attachment ofladder to structure)

• Shall be an integral part of the design.• Fastenings shall not be more than 10 feet (305 cm) apart and typically

bent bar 4 inch x 3/8 inch (102 mm x 10 mm) or equal. (Praxair) (Fig.2)




Item Design Requirements (Reference OSHA 1910.27 except where noted)1.2.4 Splices • Shall have smooth transition with original members and with no sharp

or extensive projections.1.2.5 Electrolytic Action • Adequate means shall be employed to protect dissimilar metals from

electrolytic action when such metals are joined.1.2.6 Welding • Shall be in accordance with “Code of Welding in Building

Construction” (AWS D1.0) including AWS D1.4 for reinforcing steelrungs or meet the equivalent country code.

1.2.7 Protection fromDeterioration

• Rungs and cleats shall be painted or otherwise treated to resistcorrosion and rusting when location demands. Consider 1 inch (25mm) diameter rungs in corrosive areas.

• Wood ladders, where decay may occur, shall be treated with anonirritating preservative. Detail to prevent or minimize accumulationof water on wood parts.

1.3 CLEARANCE:1.3.1 Climbing Side • Perpendicular distance from centerline of rungs to nearest permanent

object shall be 30 inches (765 mm). (Fig. 3)• Note: Required distance increases for non-vertical ladders [Max. 36

inches (915 mm) @ 76 degrees]. Required clearances for intermediatepitches varies between the 30 inches (765 mm) @ 90 degrees to the 36inches (915 mm) @ 76 degrees in proportion to the slope.

1.3.2 Ladders w/o Cages • A clear width of at least 15 inches (380 mm) shall be provided eachway from the centerline of the ladder in the climbing space, exceptwhen cages are used.

1.3.3 Chimney, WaterTank & TowerLadders

• Exempted from “Climbing Side” and “Ladder w/o Cages” but shallhave ladder safety devices provided. See Item 1.4.5.

1.3.4 Clearance in Backof Ladders

• The distance from the centerline of rungs to the nearest permanentobject in back of the ladder shall be not less than 7 inches (180 mm),except that when unavoidable obstructions are encountered, minimumclearances as follows shall be maintained for members bearing againstthe back side of the side rail: (Fig. 1)– 1-1/2 inches (40 mm) minimum from center of a rung down to top of

member.– 4-1/2 inches (115 mm) minimum from center of a rung up to bottom

of member.1.3.5 Clearance at bottom

of ladder• There shall be a level landing of 30 inch (765 mm) by 30 inch (765

mm) at the bottom of each ladder (See Fig. 3). There shall be a 30 inch(765 mm) by 30 inch (765 mm) area free of all obstructions from thebottom of the ladder cage to the landing.




Item Design Requirements (Reference OSHA 1910.27 except where noted)1.3.6 Clearance in Back

of Grab Bar• The distance from the centerline of the grab bar to the nearest

permanent object in the back of the grab bars shall not be more than 6inches (152 mm) or less than 4 inches (102 mm). (Fig. 3)

1.3.7 Step-AcrossDistance

• The distance from the nearest edge of ladder to the nearest edge ofequipment or structure shall not be more than 12 inches (305 mm) orless than 2-1/2 inches (64 mm). (Fig. 2)

1.4 SPECIAL REQUIREMENTS:1.4.1 Cages • Shall be built as shown in Figure 2.

• Shall be provided on ladders of more than 12 feet (427 cm) to amaximum unbroken length of 30 feet (915 cm). (Praxair)

• Not required on interior ladders of equipment where space is limited,such as cold boxes, concrete pits, sumps and manholes. Landings are tobe provided. Where cages are not used, provisions for tie-off cable arerequired. (Praxair)

• Hoop bars: 3 inch x ¼ inch (75 mm x 6 mm) min. steel. Vertical bars:1-1/2 inch (40 mm) x ¼ inch (6 mm) min. steel. (Praxair)

• Shall extend a minimum of 3 feet 6 inches (107 cm) above the top oflanding (front access ladders), unless acceptable protection is provided.

• Except for side access ladders (side step or offset-fixed), where cageshall extend 4 feet (122 cm) above landing. (See Fig. 2)

• Shall extend down the ladder to a point not less than 7 feet (213.5 cm)nor more than 8 feet (244 cm) above the base of the ladder

• The ascending entrance to a cage shall flare out an additional 4 inches(102 mm).

• Shall not extend less than 27 inches (685 mm) nor more than 28 inches(790 mm) from the centerline of the rungs of the ladder. Shall not beless than 27 inches (685 mm) in width. The inside shall be clear ofprojections. The bottom of the cage must be flared not less than 4inches (102 mm) between the bottom horizontal band and the nexthigher band. Vertical bars shall be located at a maximum spacing of40o around the circumference of the cage; this will give a maximumspacing of about 9-1/2 inches (240 mm), center-to-center. Vertical barsshall be a minimum of 1-1/2 inches (38 mm) wide by ¼ inch (6 mm)thick. (Praxair) Horizontal hoop bars shall be 3 inches (75 mm) wideby ¼ inch (6 mm) thick (Praxair) and spaced a maximum of 4 feet (122cm) on centers.




Item Design Requirements (Reference OSHA 1910.27 except where noted)1.4.1 Cages (Continued) • Ladder wells shall have a side clearance width of at least 15 inches (380

mm) from centerline of ladder. Ladder wells shall be smooth-walledand a minimum of 27 inches (685 mm) from the centerline of rungs towell wall on the climbing side. This clearance shall be increased to aminimum of 30 inches (765 mm) when other obstructions exist.

• The continuity of the handrail and midrail must be maintained.Therefore, the upper [at 42 inches (107 cm) standard height], middlerail and toeboard must be continued and attach to the ladder cage asapplicable.

1.4.2 Landing Platforms • When ladders are used to ascent to heights exceeding 12 feet (427 cm)[except chimneys], landing platforms shall be provided for each 30 feet(915 cm) of height or fraction thereof. (Fig. 3)

• Where a person has to step a distance greater than 12 inches (305 mm)from the centerline of the rung of a ladder to the nearest edge of struc-ture or equipment, a landing platform shall be provided. The minimumstep-across distance shall be 2-1/2 inches (65 mm).

• All landing platforms above 4 feet (122 cm) shall be equipped withstandard railings on all open sides and toeboards except where there isan entrance to a stairway, ramp, or fixed ladder.

• One rung of any section of ladder shall be located at the level of thelanding laterally served by the ladder. Where access to the landing isthrough the ladder, the same rung spacing as used on the ladder shall beused from the landing platform to the first rung below the landing.

• Platforms shall be sized to allow a minimum width of 24 inches (610mm) unencumbered egress path. For unavoidable individual pointcontacts along the egress path a minimum width of 18 inches (460 mm)is acceptable. Exception: Doors opening on to elevated platforms shallhave a minimum of 20 inches (510 mm) unencumbered egress patharound them.

1.4.3 Ladder Extensions • The side rails of ladder extensions shall extend 3 feet 6 inches (107 cm)for step through ladders or 4 feet (122 cm) for side step above parapetsand landings. For through ladder extensions, the rungs shall be omittedfrom the extension and shall have not less than 18 inches (460 mm) normore than 24 inches (610 mm) clearance between rails. A vertical grabbar shall be added on both side rails of step through ladder extensionswhere the ladder rungs have been omitted. (Praxair) For side-step oroffset fixed ladder section, at landings, the side rails and rungs shall becarried to the next regular rung beyond [4 rungs minimum]. (Fig. 3)

1.4.4 Grab Bars(Individual handholds as extension ofladder)

• Vertical grab bars shall have the same spacing as the ladder side rails.Grab bar diameters shall be the same as the rungs.




Item Design Requirements (Reference OSHA 1910.27 except where noted)1.4.5 Ladder Safety

Devices• Shall be used on tower, tank and chimney ladders over 12 feet (305 cm)

in unbroken length in lieu of cage protection. (Praxair) No landingplatform is required. All ladder safety devices such as those thatincorporate lifebelts, friction brakes, and sliding attachments shall meetthe design requirements of the ladders which they serve. An approvedwritten deviation shall be obtained from Praxair for the use of a safetydevice in lieu of cages on towers, water tanks and chimneys. (Praxair)

1.5 LADDER PITCH:1.5.1 Preferred • Ranges from 75 degrees to 90 degrees with the horizontal. (Fig. 9)1.5.2 Substandard • Ranges from 60 degrees to 75 degrees with the horizontal. Permitted

only where it is found necessary to meet conditions of installation.Avoid whenever possible. (Fig. 9)

1.5.3 Pitch greater than 90and less 60 degreesare not allow

• Pitches greater than 90 and less 60. (Fig. 4)

1.6 MISCELLANEOUS:1.6.1 Color of Ladder

Cages and Handrails• There are no color requirements for cages and handrails. Therefore,

galvanized cages and ladders do not require painting. However, ifcages and handrails are constructed of material that will be painted, it issuggested that the country color representing caution be used. In theUSA, yellow is the color representing caution.

PitchDegree with Horizontal

Item Range PreferredLadder 60°- 90° 75° - 90°Stairs 20°- 50° 30° - 38°Ramps 0° - 20° 0° - 15°



Table 2Fixed Stairways


2.1 LADDER OR STAIRWAY2.1.1 Application of

Requirements• Includes interior and exterior stairs around equipment and stairs leading

to or from floors, platforms, or pits.2.1.2 Where Fixed Stairs

are Required• Provide for access from one structure level to another where operations

necessitate regular travel between levels.• Provide for access to operating platforms at any equipment which

requires attention routinely during operations.• Suggested for daily access to elevations for gauging, inspections,

maintenance, etc., where such work may expose employees to harmfulsubstances.

• Spiral (not winding) stairways are not permitted except for special limitedusage and secondary access situations where it is not practical to provideconventional stairway.

• Winding stairways permitted on round structures over 5 feet (152.5 cm)in diameter, i.e., large diameter circular tanks (LR).

• Ladder or stairway shall be provided at all designated personnel pointsof access where there is a break in elevation of 19 inches (480 mm) ormore and no ramp, runway, sloped embankment or personnel hoist isprovided. (Praxair, also reference OSHA 1926.1051. For high-frequency areas, steps shall be provided when there is a break inelevation of 16 inches (405 mm). (Praxair)

2.1.3 Stair Design Loads • Designed and constructed to carry a load of five times the normal liveload anticipated but never less strength than to safely carry a movingconcentrated load of 1000 pounds (454 kg). (Fig. 5)

2.1.4 Stair Height • Maximum vertical heights of 12 feet (366 cm) between platforms with theexception of minimal use winding stairways.

2.1.5 Stair Width • Minimum width of 22 inches (560 mm). (Fig. 5)2.1.6 Stair Rise Angle • Installed at angles to the horizontal of between 30 and 50 degrees.

(See Table 2A)2.1.7 Stair Treads • Reasonably slip-resistant and the nosing shall be of non-slip finish.

Welded bar grating treads without nosing are acceptable providing theleading edge can be readily identified by personnel descending thestairway and provided the tread is serrated or is of definite non-slipdesign. Rise height and tread width shall be uniform throughout anyflight including any foundation structure used as one or more treads ofthe stairs. (Fig. 5)

• Stairs having treads less than 9 inches (240 mm) front to back shallhave open risers. (Praxair)



Table 2Fixed Stairways

Item Design Requirements (Reference OSHA 1910.24 except where noted)2.1.8 Stairway Platforms • Shall be no less than the width of a stairway and a minimum of 30

inches (765 mm) in length measured in the direction of travel.• Where doors or gates open directly on a stairway, a platform shall be

provided that extends at least 20 inches (510 mm) beyond the swing ofthe door. (Praxair and reference OSHA 1926.1052.a)

• Minimal usage winding stairways such as at LR tanks do not requirerest landings. (Praxair)

2.1.9 Vertical Clearance • Above any stair tread to an overhead obstruction shall be at least 7 feet(213.5 cm) measured from the leading edge of the tread. (Fig. 4)

2.1.10 Miscellaneous • Pipes shall not pass through stairs.• Stairs shall not be used as storage.

Table 2AStair Rise Angle

Preferred MarginalAngle to

HorizontalRise(In.)

Tread Run(In.)

Angle toHorizontal

Rise(In.)

Tread Run(In.)

30° 35 min. 6.50 11.00 40° 08 min. 8.00 9.5032° 08 min. 6.75 10.75 41° 44 min. 8.25 9.2533° 41 min. 7.00 10.50 43° 22 min. 8.50 9.0035° 16 min. 7.25 10.25 45° 00 min. 8.75 8.7536° 52 min. 7.50 10.00 46° 38 min. 9.00 8.5038° 29 min. 7.75 9.75 48° 16 min. 9.25 8.25

49° 54 min. 9.50 8.00Note: Rise + Tread Run = 17.5

Table 2A (continued)Stair Rise Angle (Metric Units)

Preferred MarginalAngle to

HorizontalRise(mm)

Tread Run(mm)

Angle toHorizontal

Rise(mm)

Tread Run(mm)

30° 35 min. 165 280 40° 08 min. 205 24032° 08 min. 170 275 41° 44 min. 210 23533° 41 min. 180 265 43° 22 min. 215 23035° 16 min. 185 260 45° 00 min. 225 22536° 52 min. 190 255 46° 38 min. 230 21538° 29 min. 195 250 48° 16 min. 235 210

49° 54 min. 240 205Note: Rise + Tread Run = 445



Table 3Railings


3.1 STAIRWAY RAILINGS AND GUARDS3.1.1 With four or more

risers• Provide standard railings, the width of the stair to be measured clear of

all obstructions.a) On stairways less than 44 inches (111.5 cm) wide having both sides

enclosed, at least one handrail, preferably on right side descending.b) On stairways less than 44 inches (111.5 cm) wide having one side

open, at least one stair railing on open side.c) On stairways less than 44 inches (111.5 cm) wide having both sides

open, at least one stair railing on each side.d) On stairways more than 44 inches (111.5 cm) wide but less than 88

inches (223.5 cm) wide, one handrail on each enclosed side and onestair railing on each open side.

e) On stairways more than 88 inches (223.5 cm) wide, one handrail oneach enclosed side, one stair railing on each open side and oneintermediate stair railing located about midway of the width.

3.1.2 Winding Stairs • Provide handrail offset to prevent walking on all portions of the treadshaving less than 6 inches (115 mm) width.

3.1.3 Ramps • Ramps designed specifically for handicap access to office buildings andhaving a total rise greater than 6 inches (152 mm) shall have handrailson both sides.

3.2 RAILING AND TOE BOARDS SPECIFICATIONS:3.2.1 Standard Railing on

Platforms• Top rail, intermediate rail, and posts, having vertical height of 42 inches

(107 cm) nominal from upper surface of top rail to floor, platformrunway, or ramp level. The top rail shall be a smooth continuous sur-face without any gaps. The intermediate rail shall be about halfwaybetween top rail and floor. The ends of the rails shall not overhang theterminal posts except where such overhang does not constitute aprojection hazard.



Table 3Railings

Item Design Requirements (Reference OSHA 1910.23 except where noted)3.2.2 Stair Railing • On stairways more than 44 inches (1115 mm) wide but less than 88

inches (2235 mm) wide, one handrail on each side of stairs is required.On stairways more than 88 inches (2235 mm) wide, one intermediatestair handrail is required located approximately midway of the width.

• Similar to standard railing but the vertical height shall be not more than34 inches (864 mm) nor less than 33 inches (838 mm) from uppersurface of top rail to surface of the front edge of the tread. (Praxair)Note: OSHA limits are 30 to 34 inches. Other codes limit themaximum height to 38 inches (965 mm) and the minimum height to 34inches (865 mm). 34 inches (865 mm) to 38 inches (965 mm) is theacceptable height range of the top rail surface if OSHA or localregulations do not govern. (Praxair)

• For wood systems, all members shall be at least 2 inch (51 mm) by 4inch (102 mm) with posts spaced not more than 6 feet (150 mm) oncenters, unless the top rail is made of two right-angle pieces of 1 inch(25 mm) by 4 inch (102 mm), then posts not spaced more than 8 feet.(OSHA 1910.27)

• For pipe systems, all members shall be at least 1-1/2 inches (40 mm)OD (outside diameter) but no more than 2 inch (50 mm) OD, with postsspaced not more than 8 feet (2440 mm) on centers. [Note: 1-1/4 inchnominal pipe typically used has OD of 1.660 inch (42 mm).]

• For other structural steel shapes, all materials shall be at least 2 inch by2 inch by 3/8-inch (10 mm) angles or equivalent bending strength withposts spaced not more than 8 feet (244 cm) on centers.

Note: Local-building codes may require the use of ASCE7 standards.ASCE7 requires a loading of 50 lbm/ft on handrails. This load on 8-foot (244 cm) centers would require the use of 2-1/2 inch by 2-1/2 inchby 3/8-inch (10 mm) angles. (ASCE)

• Anchoring of posts and framing members to withstand 200 pounds (91kg) or 50 lb/ft (74.55 kg/m) if required by local codes applied in anydirection at any point.

• Other systems meeting above conditions are acceptable.See Figure 6.



Table 3Railings

Item Design Requirements (Reference OSHA 1910.23 except where noted)3.2.3 Standard Toeboard • 4 inches (102 mm) nominal in vertical height from top edge of floor or

grating with no more than ¼-inch (6 mm) clearance above floor. (Fig.6) Material may be solid or with openings not over 1 inch. Reinforceunsupported toeboards and allow for fabrication tolerances andwarpage to assure the maximum allowable opening (gap) of 1 inch isnot exceeded.

• Where material is piled to such height that a standard toeboard does notprovide protection, paneling from floor to intermediate rail, or to toprails shall be provided.

• Steel toeboard to be 3/16 inch (5 mm) thick minimum. (Praxair)3.2.4 Handrails (Mounted

directly to wall orpartition)

• Lengthwise members mounted by bracket on lower side so as to offerno obstruction. Ends shall be turned in so as not to constitute a projec-tion hazard.

• Height shall be no more than 34 inches (865 mm) nor less than 30inches (765 mm) from floor or front edge of stair. Design provides tripprotection when climbing stairs, not to be used where there is a possi-bility of falling over the top railing.

• Minimum size of material: 1-1/2 inches (40 mm) outside diameter (OD)for pipe; 2 inches (50 mm) thickness for wood. Minimum clearancebetween handrail and wall or any projection shall be at least 3 inches.Bracket spacing shall not exceed 8 feet (244 cm).

• Mounting shall be able to withstand at least 200 pounds (91 kg) or ifrequired by local codes, 50 lbm/ft (74.55 kg/m) applied in any directionat any point.

3.2.5 Handrail andRailing Clearance

• Minimum clearance between handrail and wall or any projection shallbe at least 3 inches (75 mm).

3.2.6 Extended Handrail(Ladder Guard)

• Provide railing with 3 feet (920 mm) vertical extension [for a totalrailing height of 6 feet 6 inches (1990 mm)] at elevated locations wherea 4 feet (1220 mm) radius measured from the center of the ladderextends beyond the platform railings. (Praxair) (Fig. 7)



Table 4Platforms


4.1 LANDINGS4.1.1 Ladder Landing • Platforms shall be not less than 30 inches (765 mm) in width and 30

inches (765 mm) in length. For larger platforms, a minimum 30 inches(765 mm) by 30 inches (765 mm) area centered on the ladder gate mustbe free of all obstructions to a minimum height of seven feet to allowfor unencumbered ladder access and egress. (Praxair) (Fig. 3)

4.1.2 Stairway Landing • Shall be no less than the width of a stairway and a minimum of 30inches (765 mm) in length measured in the direction of travel. (OSHA1910.24.g)

• Where doors or gates open directly on a stairway, a platform shall beprovided that extends at least 20 inches (510 mm) beyond the swing ofthe door. (Praxair and reference OSHA 1926.1052.a) (Fig. 13)

• Minimal usage winding stairways such as at LR tanks do not requirerest landings. (Praxair)

4.2 DESIGN LOADS:4.2.1 Not Supporting

Equipment• Design for live load of 30 lb/ft2 (146.70 kg/m2) or snow load, whichever

is greater, plus dead load, plus any concentrated loads (such as pipesupports, etc.)

4.2.2 SupportingEquipment

• Design for live load of 75 lb/ft2 (366.75 kg/m2) or snow load, whicheveris greater, plus dead load, plus maximum equipment weight, plus anyconcentrated loads (such as pipe supports, etc.), plus any dynamicloads.

4.2.3 Standard Railings • Required on all platforms 4 feet (122 cm) or more above floor orground level.

4.2.4 Grating • Any type of grating properly designed for the imposed loads may beused. Typically used is welded steel grating with bearing bars 3/16inch (5 mm) thick, spaced 1-3/16 inches (30 mm) on center, with depthrequired for the design loading. Plank grating may also be used.Grating shall be selected so as to minimize slipping and, in the case ofexterior platforms, accumulation of snow and ice. When necessary,gratings with optional slip resistant surfaces shall be used. Gratingshall be secured in place. Grating opening shall not allow a 1-inch (25mm) by 1-inch (25 mm) object to pass through. (Fig. 11E or 11M)



Table 4Platforms

Item Design Requirements (Reference OSHA 1910.27 except where noted)4.2.5 Grating Openings • The maximum size of an unprotected floor opening shall be 1 inch wide

by the length of the grating bearing bar spacing. All cutouts and open-ings that are to be provided and banded by the manufacturer shall beshown on the design drawings. All openings with gaps greater than 1inch (25 mm) shall have a minimum 4 inch (102 mm) high bandingabove the grating to act as toeboard. Gaps greater than 4 inches (102mm) between the banding and piping penetration are unacceptable.(Figs. 10E or 10M, 11E or 11M)

4.2.6 Openings Betweenthe Edge of Plat-forms and AdjacentStructures

• Openings greater than 4 inches (102 mm) between the end of the plat-form and an adjacent structure are unacceptable unless they are guardedby handrails or the openings are covered with standard grating or plate.(Fig. 12E or 12M)

4.2.7 Hinged GratingSections

• Provide as required to allow access to manholes or other equipmentlocated below platforms and walkways. The hinged grating shall bepermanently attached to fixed grating to prevent grating from fallingthrough opening when being opened.

4.2.8 Swing Gates • Provide self-closing type directly across from ladder openings on plat-forms. Gates must be of a U-shaped design with an 18 inch (460 mm)minimum width to a 24 (610 mm) inch maximum width. The gate mustbear on the handrail column opposite the pivot-connected side. Pivot(hinge) side to be on far side of ladder. (Fig. 7) Suggested prefab-ricated safety gate assemblies are shown on Civil Detail # 05500-311,located in directory:\\tonsrv1\ACAD2\Standards\Details\Civil\05_Metal_Steel(reference Section 4). (Praxair)

• Metal-to-metal, gravity-type, self-closing gates are not acceptable sincethe metal-to-metal contact area deteriorates and the gates stick open. Aspring-return must be used for better reliability. (Praxair)



Table 5Floor and Wall Openings


5.1 PROTECTION FOR FLOOR OPENINGS:5.1.1 Stairway • Guarded by standard railing on all exposed sides, except at entrances.5.1.2 Ladderway • Guarded by standard railing and toeboard on all exposed sides, except

entrance.5.1.3 Hatchway and

Chute• Guarded by one of the following:

a) Hinged cover with standard railings to leave only one exposed side.When opening not in use, the cover shall be closed or exposed sideshall be covered with removable standard railing. When the design ofa hinged cover is such that in the open position wind or personnelcould cause the cover to fall closed, a hold-open device is required.Typically a chain and clip meets this requirement.

b) A removable railing with toeboard on no more than two sides andfixed standard railing with toeboard on all other exposed sides. Keepremovable in place when not in use.

5.1.4 Skylight • Guarded by standard skylight screen or fixed standard railing on allexposed sides.

5.1.5 Pit or Trapdoor • Guarded by cover.5.1.6 Manhole • Guarded by standard manhole cover which need not be hinged. When

the design of a hinged cover is such that in the open position wind orpersonnel could cause the cover to fall closed, a hold open device isrequired. Typically a chain and clip meets this requirement.

5.1.7 Temporary • Opening shall be protected by removable standard railings or othersuitable barrier.

5.1.8 Floor holes intowhich people canwalk

• Guarded by either:a) Standard railing and toeboard on all exposed sides.b) Use of a cover. When cover not in place, opening shall be constantly

attended by someone or shall be protected by removable standardrailings.

5.1.9 Floor holes intowhich people cannotwalk

• Protected by securely held in place cover that leaves no openings morethan 1 inch (25 mm) wide.

5.1.10 Doors or gates opendirectly to stairway

• Provide platform where swing of door does not reduce effective widthto less than 20 inches (510 mm). (Fig. 13)





5.2 PROTECTION FOR WALL OPENINGS AND HOLES:5.2.1 All, with more than

4 feet (122 cm) drop• Guarded by one of the following:

a) Rail, roller picket fence, half door, or equivalent barrier. Whereexposure below to falling materials, provide a removable toeboard orequivalent. Provide grab bar on each side of opening with its centerabout 4 feet (122 cm) above floor level.

b) Extension platform with side rails onto which material can be hoistedfor handling.

5.2.2 Chute • Same as item 5.2.1 above.5.2.3 Window, with more

than 4 feet (122 cm)drop

• At landing, floor, platform, or balcony where the bottom is less than 3feet above floor, shall be guarded by standard slats, grills, or railings.

5.2.4 Temporary • Adequate guards suitable for the circumstance.5.2.5 Where hazard of

material fallingthrough

• When lower gap between the hole and the penetration object is greaterthan 1 inch (25 mm) the hole must be banded with plate that extends 4inches (102 mm) above the platform floor. The gap between thebanded plate and the penetration shall not exceed 4 inches (102 mm).(Praxair) (Fig. 10)

5.3 PROTECTION OF OPEN-SIDED FLOORS, PLATFORMS AND RUNWAYS5.3.1 Every 4 feet (122

cm) or more aboveadjacent floor orgrade

• Guarded by standard railing on all open sides except where there is anentrance ramp. Provide toeboard whenever, beneath the open sides: (i)persons can pass, (ii) there is moving machinery, or (iii) there isequipment with which falling materials could create a hazard.

5.3.2 Runway • Same as 5.3.1 above.5.3.3 Regardless of height

and adjacent to dan-gerous equipment orhazards

• Guarded with standard railing and toeboard.

5.4 COVER SPECIFICATIONS:5.4.1 Floor Opening

Cover Material• Any material that meets the following:

a) Manhole, trench or conduit covers and supports, when located inplant roadways, shall be designed to carry a truck rear-axle load of atleast 20,000 pounds (9090 kg).

b) Covers projecting not more than 1 inch (25 mm) above floor may beused providing all edges are chamfered to an angle of not over 30degrees. Incidentals to be flush.

5.4.2 Skylight Screens • Capable of withstanding a load of at least 200 pounds (91 kg) appliedperpendicular to screen.




Item Design Requirements (Reference OSHA 1910.23 except where noted)5.4.3 Wall Opening

Barrier• Capable of withstanding a load of at least 200 pounds (91 kg) applied in

any direction.5.4.4 Wall Opening Grab

Handles• Capable of withstanding a load of at least 200 pounds (91 kg) applied at

any point. The handles shall be not less than 12 inches (305 mm) andmounted to give 3 inches (75 mm) clearance from the side framing ofthe opening.

5.4.5 Wall OpeningScreens

• Capable of withstanding a load of at least 200 pounds (91 kg) applied atany point.

Table 6Top of Domed Structures Requiring Access

Item Design Requirements

6.1 DOMED CASINGS6.1.1 Domed Casing with

Grating Walkwayand No DomeWalking Surface

• Provide standard railing and standard toeboard system for walkway.(Praxair)

• Provide a standard toeboard around the perimeter of the casing at theintersection of the dome and casing. (Praxair)

6.1.2 Domed Casing withDome WalkwaySurfaces

• Provide handrail and toeboard system at least 5 feet (153 cm) high with2 intermediate rails at about 18 inches (460 mm) on center. Provide a36 inch (915 mm) high chain link fencing mesh attached to the insidebottom of the railing system. (Praxair) (Fig. 7)

• Provide grating banded edge finish on surfaces facing walkwaysurfaces. (Praxair)

• Provide domed surface with non-slip finish. (Praxair)

standard de praxair segÚn norma osha

Documents

unencumbered

nearest permanent

open position

gates open

praxair standard

removable

fixed standard

require rest