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Subchapter 7. General Industry Safety Orders
Group 1. General Physical Conditions and Structures Orders
Article 2. Standard Specifications

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§3234. Fixed Industrial Stairs.

(a) Scope. This Section contains specifications for the safe design and construction of fixed general industrial stairs. This classification includes interior and exterior stairs around machinery, tanks, and other equipment, and stairs leading to or from floors, platforms, or pits. This Section does not apply to stairs used for required exit purposes, to construction operations, to private residences, or to articulated stairs, such as may be installed on floating roof tanks or on dock facilities, the angle of which changes with the rise and fall of the base support. (Title 24, Part 2, Section 2-3326(a).)

(b) Where Fixed Stairs Are Required.

(1) Fixed stairs shall be provided for access from one structure level to another where operations necessitate regular travel between levels, and for access to operating platforms at any equipment which requires attention routinely during operations. Fixed stairs shall also be provided where access to elevations is daily or at each shift for such purposes as gauging, inspection, regular maintenance, etc., where such work may expose employees to acids, caustic, gases, or other harmful substances, or for which purposes the carrying of tools or equipment by hand is normally required. (It is not the intent of this Section to preclude the use of fixed ladders for access to elevated tanks, towers and similar structures, overhead traveling cranes, etc., where the use of fixed ladders is common practice.)

(2) Spiral stairways shall not be permitted except for special limited usage and secondary access situations where it is not practical to provide a conventional stairway.

(3) Winding stairways may be installed on tanks and similar round structures where the diameter of the structure is not less than 5 feet.

(Title 24, Part 2, Section 2-3326(b).)

(4) Alternating tread stairs, meeting the requirements of 3234(i) shall be permitted for:

(A) Limited usage.

(B) Secondary access.

(c) Stair Strength. Fixed stairways shall be designed and constructed to carry a load of 5 times the normal live load anticipated but never of less strength than to carry safely a moving concentrated load of 1,000 pounds. (Title 24, Part 2, Section 2-3326().)

(d) Stair Width. Fixed stairways shall have a minimum usable width of 22 inches. No chute or open conveyor shall be parallel to and adjoin a stairway unless the usable width of the stairway is at least 22 inches and the stairway is equipped with a stair railing separating the chutes and open conveyors from the stairway.

Chutes shall not be hinged or otherwise constructed or used so as to cover stairways. (Title 24, Part 2, Section 2-3326(d).)

(e) Angle of Stairway Rise.

(1) Fixed stairs shall be installed at angles to the horizontal of between 30 and 50 degrees.

(2) Any uniform combination of rise-tread dimensions may be used that will result in a stairway at an angle to the horizontal within the permissible range.

(3) The following is a table of rise/tread dimensions which will produce a stairway within the permissible range, stating the angle to the horizontal produced by each combination. However the rise/tread combinations are not limited to those given below.

(4) Each tread and the top landing of a stairway, where risers are used, shall have a nose which extends one-half-inch to one-inch beyond the face of the lower riser. Noses shall have an even leading edge.

(5) All treads shall be slip-resistant.


                        Table IS-1. 

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 Angle to                 Rise                       Tread Run

Horizontal             (in inches)                  (in inches)

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30° 35'                  6 1/2                       11

32° 08'                  6 3/4                       10 3/4

33° 41'                  7                           10 1/2

35° 16'                  7 1/4                       10 1/4

36° 52'                  7 1/2                       10

38° 29'                  7 3/4                       9 3/4

40° 08'                  8                           9 1/2

41° 44'                  8 1/4                       9 1/4

43° 22'                  8 1/2                       9

45° 00'                  8 3/4                       8 3/4

46° 38'                  9                           8 1/2

48° 16'                  9 1/4                       8 1/4

49° 54'                  9 1/2                       8

Welded bar grating treads without nosings are acceptable providing the leading edge can be readily identified by personnel descending the stairway and provided the tread is serrated or is of definite non-slip design.

(6) Rise height and tread width shall be uniform throughout any flight of stairs including any foundation structure used as one or more treads of the stairs.

The maximum variations in the height of risers or the width of treads in any one flight shall be one-fourth-inch.

(7) Where the rise would exceed 9 1/2 inches and the run would be less than 8 inches, portable, fixed, or ships ladders shall be used.

(Title 24, Part 2, Section 2-3326(e).)

(f) Stairway platforms shall be no less than the width of a stairway and minimum of 30 inches in length measured in the direction of travel. (Title 24, Part 2, Section 2-3326(f).)

(g) Stair Railings and Handrails.

(1) Stair railings shall be provided on the open sides of all exposed stairways.

(2) Handrails shall be provided on at least one side of closed stairways, preferably on the right side descending.

(3) Stair railings and handrails shall be installed in accordance with the provisions of Section 3214.

(4) Standard guardrails shall be installed on stairway platforms. See Section 3209. (Title 24, Part 2, Section 2-3326(g).)

(h) Vertical Clearance. Vertical clearance above any stair tread to an overhead obstruction shall be at least 6 feet 6 inches measured from the leading edge of the tread.

In existing installations where the overhead clearance is less than 6 feet 6 inches, the obstruction shall be removed, or if this is impracticable, a suitable warning shall be placed near the obstruction so as to notify employees of its presence. Where the nature of the hazard is such that padding it will increase safety, this also shall be done. (Title 24, Part 2, Section 2-3326(h).)

(i) Alternating Tread Stairs.

(1) The stairs shall have a series of steps between 50 and 70 degrees from horizontal.

(2) Stair rails, designed to provide employees an adequate handhold to avoid falling, shall be provided on both sides of the stair.

(3) A minimum distance of 6 inches shall be provided between the stair rail and any fixed structure, machine or other object.

(4) A minimum of 12 inches shall be provided between the stair rails of adjacent alternating tread type stairs.

(5) The stair shall have:

(A) A minimum of 17 and a maximum of 24 inches of width between the stair rails.

(B) A minimum tread depth of 8 1/2 inches, a minimum tread width of 7 inches, a minimum tread run of 5 inches and a maximum rise to the next alternating tread surface of 9 1/2 inches.

(C) A minimum usable width of 17 inches.

(6) The initial tread of the stair shall begin at the same elevation as the platform or landing.

(7) The stair shall meet all other requirements of Sections 3214 and 3234.

EXCEPTION: The installation of a midrail and toeboard is not required.

NOTE: Authority cited: Section 142.3, Labor Code. Reference: Section 142.3, Labor Code.

HISTORY

1. New section filed 6-20-75; effective thirtieth day thereafter (Register 75, No. 25).

2. Amendment filed 7-16-76; effective thirtieth day thereafter (Register 76, No. 29).

3. Amendment of subsection (g) filed 10-5-77; effective thirtieth day thereafter (Register 77, No. 41).

4. Amendment of subsection (h) and repealer of subsection (i) and Figure IS-1 filed 7-26-78; effective thirtieth day thereafter (Register 78, No. 30).

5. Amendment filed 5-25-83; effective thirtieth day thereafter (Register 83, No. 22). Approved by State Building Standards Commission 1-24-83.

6. Amendment of subsection (b)(4) and new subsection (i) filed 6-3-85; effective thirtieth day thereafter (Register 85, No. 23).

7. Amendment of subsections (e)(4) and (f) filed 7-8-85; effective thirtieth day thereafter (Register 85, No. 28).

8. Editorial correction of subsection (f) filed 8-29-85; effective thirtieth day thereafter (Register 85, No. 35).

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