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Subchapter 7. General Industry Safety Orders
Group 8. Points of Operation and Other Hazardous Parts of Machinery
Article 64. Pulp, Paper and Paperboard Mills

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§4415. Stock Preparation and Reprocessing.

(a) Digester Valves and Piping.

(1) The digester blow valve shall be arranged so as to be operated from another room, remote from safety valves.

(2) Digester piping installed after May 30, 1999, shall conform with Sections 122-135 ASME B31.1-19957, Power Piping, which is hereby incorporated by reference. Digester piping installed on or before May 30, 1999, shall conform with either Sections 122-135 ANSI B31.1-1977, or the updated version of the ANSI/ASME B31.1 standard in effect at the time of installation.

(3) Couplings and flanges shall be secured by bolted studs.

(4) Digester blow valves or controls shall be pinned or locked in closed position throughout the entire cooking period.

(5) Heavy-duty pipe, valves, and fitting shall be used between digester and blow-pit. The piping system shall be inspected at least semiannually to determine the degree of deterioration and, repaired or replaced when necessary.

(6) Test holes in blow lines of piping systems shall not be covered with insulation or other materials.

(b) Blowing Digester.

(1) Audible warning signals and red warning lights shall be installed in areas which may be hazardous to personnel while digesters are being blown. Such devices shall be activated prior to blowing a digester and the warning lights shall remain lighted as long as the hazard exists.

(2) After the digester has started to be blown, the blow-off valve shall be left open, and the hand plate shall not be removed until the person responsible signals the blow-pit person that the blow is completed.

(3) Whenever it becomes necessary to remove the hand plate to clear stock, operators shall wear eye protection equipment and protective clothing to guard against burns from hot stock.

(c) Blow pits and blow tanks.

(1) When located on top, openings shall be provided with guardrails.

NOTE: Blow-pit openings should be on the side of the pit.

(2) The blow-pit door shall remain open when the access ladder is in place or when employees are in the blow-pit.

(3) A signaling device shall be installed in the digester, blow-pit rooms and chip bins to be operated as a warning before and while digesters are being blown.

(4) Blow-pit hoops shall be maintained in a safe condition.

NOTE: Sections (a), (b), and (c) pertain to batch digesters.

(d) Bleach Plant.

(1) An audible emergency alarm system shall be installed and it shall be activated whenever a serious leak or break develops in the bleach plant area.

(2) Chlorine gas shall be exhausted from the bleach plant by an exhaust system meeting the requirements of Article 107.

(3) The gas shall be rendered neutral or harmless before being discharged into the atmosphere.

(4) The requirements of ANSI Z9.2-1979 shall apply.

(e) Pulping Device.

(1) When beaters are fed from the floor above, the chute opening, if less than 42 inches from the floor, shall be provided with a standard railing or other enclosure. Openings for manual feeding shall be sufficient only for entry of stock and shall be provided with at least two permanently secured crossrails, in accordance with Section 3209.

(2) When beaters are fed manually from the floor above, an emergency stop control within reach of the operator's normal work station shall be provided at the top level.

(3) Where the opening is large enough to admit a worker, any employee feeding the pulper shall be secured with a safety belt with attached lifeline.

(4) Guardrails 42 inches high shall be provided around beaters where tub tops are less than 42 inches from the floor.

(f) Shredders, Cutters, Dusters, and Blowers.

(1) On manually fed shredders, cutters, and dusters, the feed table shall be of such height and distance from the knives as to prevent the operator from reaching or falling into the knives or the operator shall be safeguarded by other acceptable means.

(2) Any manually fed cutter, shredder, or duster shall be provided with a smooth-pivoted idler roll resting on the stock or feed table in front of feed rolls except when arrangements prevent the operator from standing closer than 36 inches to any part of the feed rolls.

(3) Hoods of cutters, shredders, and dusters shall be provided with exhaust ventilation in accordance with Article 107.

(4) The blower discharge outlets and work areas shall be arranged to prevent material from falling onto workers.

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


1. Repealer and new section filed 9-15-86; effective thirtieth day thereafter (Register 86, No. 38).

2. New subsection (e)(4) and amendment of subsections (f)-(f)(2) filed 12-7-92; operative 1-6-93 (Register 92, No. 50).

3. Amendment of subsection (a)(2) filed 4-30-99; operative 5-30-99 (Register 99, No. 18).

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