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Subchapter 20. Tunnel Safety Orders
Article 19. Shafts and Hoisting Systems

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§8497. Wire Rope and Sheaves.

(a) Factor of Safety. All rope to be used for regular hoisting shall be wire rope providing a factor of safety not less than five to one for material hoist and ten to one for personnel hoist when new, which shall be calculated by dividing the breaking strength of the wire rope as given in the manufacturer's published tables, by the total load to be hoisted including the total weight of the wire rope in the shaft when fully let out, plus a proper allowance for impact and acceleration.
The acceleration allowance shall be in accordance with manufacturer's recommendations, but in all cases the factor of safety of five or more must be maintained when the load, used in determining it, is greater than the actual weight by a percentage that is numerically three times the acceleration or deceleration, whichever is greatest. For example, a deceleration or acceleration of two feet per second that increases the load would require use of an effective load 6 percent greater than the actual weight, in the calculation of a factor of safety.
(b) Wire Rope Fastenings. Every wire rope used for hoisting shall be securely fastened at both ends and when in use shall not be fully unwound; at least three full turns shall remain on the drum so as to protect the end fastening at drum from overload. The wire rope end at the cage, skip or bucket shall be securely fastened by a properly made tapered socket joint, by an eye in the wire rope made with an oval thimble and wire rope clips, or by another method acceptable to the Division for this or similar service. If the wire rope clip method is used, the spacing and number used shall be as shown in Table - 1 for U-Bolts and in Table - 2 for Fist-Grip clips based upon using RRL or RLL wire rope, 6 x 19 or 6 x 37 Class, FC or IWRC; IPS or XIP. If Seale construction or similar large outer wire type construction in the 6 x 19 Class is to be used for sizes 1 inch and larger, add one additional clip. If a pulley (sheave) is used for turning back the wire rope, add one additional clip.
The number of clips shown also applies to rotation-resistant RRL wire rope, 8 x 19 Class, IPS, XIP, sizes 1-1/2 inch and smaller; and to rotation-resistant RRL wire rope, 19 x 7 Class, IPS, XIP (sizes 1-3/4 inch and smaller for U-Bolts and size 1-1/2 inch and smaller for Fist Grips).
NOTE: Wire rope abbreviation used above --
Right Regular Lay
Right Lange Lay
Fiber Rope Core
Independent Wire Rope Core
Improved Plow Steel
Extra Improved Plow Steel
Table 1 - Manufacturer's Recommendation for Using U-Bolt with Thimble Terminations
Table 2 - Manufacturer's Recommendation for Using Fist Clips with Thimble Terminations.
(c) Unsafe Wire Rope. No wire rope shall be used for hoisting when:
(1) There are 6 broken wires in one rope lay or 3 broken wires in one strand of a rope lay, or
(2) Wires on the crown are worn to 65 percent of their original diameter, or
(3) Kinking, birdcaging, high stranding, displacement or distortion of the rope structure exists, or
(4) Heat damage or marked corrosion exists, or
(5) Conditions exist which exceed the wire rope manufacturer's removal criteria.
(6) Loss of more than ten percent of rope strength as determined by nondestructive testing.
(d) Splicing. Spliced wire rope shall not be used, except that the end may be attached to the load by the thimble and/or clip method, as provided in subsection (b) of this section.
(e) Sheave and Drum Diameters. Each head sheave and hoist drum shall have a minimum diameter, according to the type of wire rope used, as follows:
6 x 7 wire rope
42 times rope diameter
6 x 19 wire rope
30 times rope diameter
6 x 37 wire rope
18 times rope diameter
8 x 19 wire rope
21 times rope diameter
(f) End Connections.
(1) A safety hook, shackle or other means providing closed design protection shall form the attachment between rope and a bucket, cage, skip or load. The attachment shall be made so that the force of the hoist pull, vibration, misalignment, release of lift force, or impact will not disengage the connection. Moused or open-throat hooks with light safety latches do not meet this requirement.
(2) All wire rope fittings and connections shall be in accordance with the manufacturers' specifications and compatible with the type of wire rope used.
(3) Spin-type connections, where used, shall be maintained in a clean condition and protected from foreign objects that could affect their operation.
(4) Where wire rope wedge sockets are used, means shall be provided to prevent wedge escapement and to ensure the wedge is properly seated.
(g) Drum Flanges. The drum of any hoist used for hoisting shall have flanges which extend at least 2 inches radially beyond the last layer of rope when all the rope is coiled on the drum.
Note: Authority cited: Sections 142.3 and 7997, Labor Code. Reference: Sections 142.3 and 7997, Labor Code.
1. Renumbering and amendment of former section 8497 to section 8494 and new section heading, section and Note filed 3-5-96; operative 4-4-96 (Register 96, No. 10).
2. Editorial correction of subsection (g) (Register 2013, No. 16).
3. Amendment of subsection (a) filed 1-9-2014; operative 4-1-2014 (Register 2014, No. 2).

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