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Subchapter 14. Petroleum Safety Orders--Drilling and Production
Article 14. Reservoirs and Stationary Tanks
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§6546. Reservoirs and Stationary Tanks.

(a) Design and construction of stationary tanks shall be in accordance with the provisions of the General Industry Safety Orders, Article 145.

(b) Tank roofs shall be capable of supporting anticipated live loading.

(c) Where it is necessary for employees to gage, sample, or perform other operating duties at a tank roof level or from or on tank roofs, safe access to the roof shall be provided.

(1) Locations on tank roofs where operating duties are performed shall be provided with safe platforms and safe means of access. A walkway will be accepted as a safe platform if the operating duties are performed entirely from the walkway.

(2) If such duties are performed from a ladder providing access to the tank top, the ladder shall be equipped with a cage, ring, or equivalent protection to support the employee while performing such duties.

(d) Where the means of access, the walkways, or the platforms of a group of two or more tanks are connected, there shall be a safe alternate means to permit an employee to escape from the roof, walkway or platform 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 emergency. This subsection shall not apply to tanks containing non-combustible liquids.

(e) Within this subsection tanks shall be classified as follows:

Class A--Tanks with fixed steel roofs, except steel waterseal roofs.

Class B--Tanks with nonmetal roofs.

Class C--Tanks with steel waterseal roofs.

Walkways and platforms on tank roofs required by subsections (c) and (d) of this section, and the railings and toeboards, shall be provided as follows:

(1) The roofs of Class A tanks shall have walkways as follows:

(A) Tank roofs having a thickness less than one-eighth inch (1/8") shall not be used as a walkway regardless of the slope of the roof. In measuring the thickness of metal roofs, allowance shall be made for manufacturer's tolerances.

(B) Tank roofs having a slope of two inches (2") or less per foot may be used as a walkway. Such walkways shall be clearly defined by color contrast, and if the slope of the tank roof is one inch (1") or more per foot the walkway shall have a nonskid surface.

(C) Tank roofs having a slope greater than two inches (2") per foot shall be provided with independent walkways of steel or wood.

(2) Class B and C tank roofs shall have independent walkways of metal or wood.

(3) No independent walkways on Class A or B tank roofs shall have a slope greater than three inches (3") per foot.

(4) No walkway on Class A or B tank roofs shall have a transverse slope greater than two inches (2") per foot.

(5) Walkways on tank roofs shall have a minimum clear width of 20 inches (20"). Walkways shall be designed to carry the load to the supporting structure of the tank roof and shall be securely attached to the tank.

(6) Platforms on Class A, B and C tanks shall be at least equivalent in safety to the type of walkway required for the tank class.

(7) Class A, B and C tanks more than 30 inches (30") above ground or floor level below shall either:

(A) Have railings and toeboards at those portions of their walkway and platform edges that are within six feet (6') of the roof edge; or

(B) Have railings and toeboards on tank edges that are within six feet (6') of the walkways or platforms.

Toeboards are not required on the side of a platform that faces the peak of the roof, unless their absence would create a hazard to employees.

(f) Where a roof is found to be unsafe, barriers shall be erected to block off the entire roof or that portion which is unsafe. Legible signs shall be posted at all approaches to the tank or reservoir if the entire roof is blocked off, or on the barrier facing all approaches to the defective area if only the unsafe portion is barricaded. These signs shall read: "Danger--Unsafe Roof--Keep Off," or equivalent wording, in letters at least two inch (2") high.

(g) Tank roofs, platforms, walkways and stairways shall be kept clear of loose material or equipment except for sampling and gaging equipment kept on tank roofs in special racks or containers. Oil spills shall be cleaned up to prevent fire and slipping hazards.

(h) When in the open position, the covers of gage, sampling and manhole openings in tank roofs shall be securely attached to the roof or roof opening fixture.

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


1. Amendment filed 7-20-59; effective thirtieth day thereafter (Register 59, No. 12).

2. Amendment of article 14 heading, section heading, section and Note filed 5-8-95; operative 6-7-95 (Register 95, No. 19).

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