CCLME.ORG - DIVISION 1. DEPARTMENT OF INDUSTRIAL RELATIONS CHAPTERS 1 through 6

(continued)
(g) Any welding necessary when making repairs or alterations to tanks shall be done by welders and welding procedures qualified in accordance with Section IX of the ASME Code in the position or positions used in making the repair.

s 513. Anhydrous Ammonia Refrigeration Systems.
Mechanical refrigeration systems using anhydrous ammonia as a refrigerant shall be installed and maintained according to the provisions of the General Industry Safety Orders.

s 514. Installation of Refrigerated Storage Containers.
(a) Containers shall be supported on suitable noncombustible foundations designed to accommodate the type of container being used.
Adequate protection against flotation or other water damage shall be provided wherever high flood water might occur.
Containers for product storage at less than 32 degrees F shall be supported in such a way, or heat shall be supplied, to prevent the effects of freezing and consequent frost heaving.
(b) A check valve shall be installed in lieu of the required excess flow valve on the fill connection, except when flow is needed in both directions, and a remotely operated shutoff valve shall be installed on all other connections located below the maximum liquid level.
(c) The filling density for refrigerated storage containers shall be such that the container will not be liquid full at a liquid temperature corresponding to the vapor pressure at the start-to-discharge pressure setting of the safety-relief valve.
(d) Safety-relief valves shall be set to start-to-discharge at a pressure not in excess of the design pressure of the container and shall have a total relieving capacity sufficient to prevent a maximum pressure in the container of more than 120 percent of the design pressure. Relief valves for refrigerated storage containers shall be self-contained spring-loaded, weight-loaded, or self-contained pilot-operated type.
The total relieving capacity shall be the larger of:

(1) Possible refrigeration system upset such as (A) cooling water failure, (B) power failure, (C) instrument air or instrument failure, (D) mechanical failure of any equipment, (E) excessive pumping rates.
(2) Fire exposure determined in accordance with Compressed Gas Association (CGA) S-1, Part 3, Safety Relief Device Standards For Compressed Gas Storage Containers, 1959, except that "A" shall be the total exposed surface area in square feet up to 25-foot above grade or to the equator of the storage container if it is a sphere, whichever is greater. If the relieving capacity required for fire exposure is greater than that required by (1) of this subdivision, the additional capacity may be provided by weak roof-to-shell seams in containers operating at essentially atmospheric pressure and having an inherently weak roof-to-shell seam. The weak roof-to-shell seam is not to be considered as providing any of the capacity required in (1) of this subdivision.
If vent lines are installed to conduct the vapors from the relief valve, the back pressure under full relieving conditions shall not exceed 50 percent of the start-to-discharge pressure for pressure balanced valves or 10 percent of the start-to-discharge pressure for conventional valves. The vent lines shall be installed to prevent accumulation of liquid in the lines.

The valve or valve installation shall provide weather protection.
Atmospheric storage shall be provided with vacuum breakers. Ammonia gas, nitrogen, methane, or other inert gases can be used to provide a pad.
(e) Appurtenances shall be protected against tampering and physical damage.
(f) Containers of such size as to require field fabrication shall, when moved and reinstalled, be reconstructed and reinspected in complete accordance with the requirements under which they were constructed. The containers shall be subjected to a pressure retest and if rerating is necessary, rerating shall be in accordance with applicable requirements.
(g) Precaution shall be taken against damage from vehicles.
(h) The total refrigeration load shall be computed as the sum of the following:
(1) Load imposed by heat flow into the container caused by the temperature differential between design ambent temperature and storage temperature.

(2) Load imposed by heat flow into the container caused by maximum sun radiation.
(3) Maximum load imposed by filling the container with ammonia warmer than the design storage temperature.
More than one storage container may be handled by the same refrigeration system.
(i) A minimum of two compressors shall be provided, either of which shall be of sufficient size to handle the loads listed in Section 514(h)(1) and (2). Where more than two compressors are provided, minimum standby equipment equal to the largest normally operating equipment shall be installed. Filling compressors may be used as standby equipment for holding compressors.
Compressors shall be sized to operate with a suction pressure at least 10 percent below the minimum setting of the safety valve(s) on the storage container and shall withstand a suction pressure at least equal to 120 percent of the design pressure of the container.
(j) Each compressor shall have its individual driving unit.
An emergency source of power of sufficient capacity to handle the loads listed in Section 514(h)(1) and (2) shall be provided unless facilities are available to safely dispose of vented vapors while the refrigeration system is not operating.
(k) The refrigeration system shall be arranged with suitable controls to govern the compressor operation in accordance with the load as evidenced by the pressure in the container(s).
An emergency alarm system shall be installed to function in the event the pressure in the container(s) rises to the maximum allowable operating pressure.
An emergency alarm and shutoff shall be located in the condenser system to respond to excess discharge pressure caused by failure of the cooling medium.
All automatic controls shall be installed in a manner to preclude operation of alternate compressors unless the controls will function with the alternate compressors.
( l) An entrainment separator of suitable size and design pressure shall be installed in the compressor suction line of lubricated compression. The separator shall be equipped with a drain and gaging device.
An oil separator of suitable size shall be installed in the compressor discharge line. It shall be designed for at least 250 p.s.i. and shall be equipped with a gaging device and drain valve.
(m) The condenser system may be cooled by air or water or both. The condenser shall be designed for at least 250 p.s.i. Provision shall be made for purging noncondensibles either manually or automatically.
(n) A receiver shall be provided with a liquid-level control to discharge the liquid ammonia to storage. The receiver shall be designed for at least 250 p.s.i. and be equipped with the necessary connections, safety valves, and gaging device.
(o) Refrigerated containers and pipelines which are insulated shall be covered with a material of suitable quality and thickness for the temperatures encountered. Insulation shall be suitably supported and protected against the weather. Weatherproofing shall be of a type which will not support flame propagation.

Note: Authority cited: Section 142.3, Labor Code.

s 515. Systems Utilizing Portable DOT NH sub3 Containers.
(a) Cylinders shall comply with DOT specifications and shall be maintained, filled, packaged, marked, labeled, and shipped to comply with 49 CFR Chapter 1 and Marking Portable Compressed Gas Containers to Identify the Material Contained, ANSI Z48.1-1954 (R1970).
(b) Cylinders shall be stored in an area free from ignitable debris and in such manner as to prevent external corrosion. Storage may be indoors or outdoors.
(c) Cylinders filled in accordance with DOT regulations will become liquid full at 145 degrees F. Cylinders shall be protected from heat sources such as radiant flame and steampipes. Heat shall not be applied directly to cylinders to raise the pressure.
(d) Cylinders shall be stored in such manner as to protect them from moving vehicles or external damage.
(e) Any cylinder which is designed to have a valve protection cap shall have the cap securely in place when the cylinder is not in service.

Note: Authority cited: Section 142.3, Labor Code.

The provisions of Article 7 apply to the storage, dispensing and use of natural
gas as a motor fuel, but do not apply to the storage or use of natural gas on
public roads and highways.

s 523. Design and Construction of Natural Gas Tanks.
(a) General. All new natural gas tanks shall be constructed, inspected, and stamped in compliance with the Code, unless the design, material, and construction of the tank are accepted by the Division as equivalent to code.
(b) Compressed Natural Gas. In addition to the stamping required by the Code, the stamping on all new CNG tanks shall include the following:
(1) Volumetric capacity in standard cubic feet of natural gas when filled to the limits provided by these regulations.
(2) The words "For CNG."
(3) The head and shell thicknesses.
(c) Liquefied Natural Gas. The outer vessel of double wall cryogenic vessels shall be designed for the full range of pressure and/or vacuum to which it will be subjected and for adequate structural support of the inner tank and insulation under all imposed loadings. Equipment shall For Appendix A, refer to end of subchapter 1.
In addition to the stamping required by the Code, the stamping for all new LNG tanks shall include the following:
(1) Net volumetric capacity in U. S. gallons.
(2) The words "For LNG."

(3) The head and shell thicknesses.
(4) Minimum safety relief valve capacity in cfm air. See 541 (c) (1) and (2).
[FNa1] For Appendix A, refer to end of Subchapter 1.

Note: Authority cited: Section 142.3, Labor Code. Reference: Section 142.3, Labor Code, and Chapter 855, Statutes of 1977.

s 524. Design and Construction of Compressed Natural Gas Cylinders.
All new natural gas cylinders shall be constructed for the service pressure specified in and meet other DOT regulations.
[FNa1] For Appendix A, refer to end of Subchapter 1.

s 525. Design and Construction of LNG Vaporizers.
[FNa1] For Appendix A, refer to end of Subchapter 1.

s 526. Repairs and Alterations to Tanks, Welded Piping and to Welded Vaporizers Having a Volumetric Capacity in Excess of 1 U. S. Gallon.
(a) No repairs or alterations involving flame, arc or other method of welding shall be made on any tank, vaporizer or piping unless such tank, vaporizer or piping shall first have been certified as natural gas free or oxygen free by competent personnel.
(b) No repair or alteration to a natural gas tank or welded vaporizer which affects the safety of such natural gas tank or welded vaporizer shall be made until the contemplated repair or alteration has been authorized by a qualified inspector. The exchange or interchange of valves, fittings and accessories intended for the same purpose need not be considered a repair or alteration.
(c) No tank, vaporizer or piping system that has been subjected to possible damage by fire shall be returned to service until it has been inspected by a qualified inspector and found to be safe.
(d) Any vessel, vaporizer or piping requiring repair or alteration or that has been subjected to a fire shall be prepared for hydrostatic test by the owner when such test is deemed necessary by the qualified inspector.
(e) No repairs shall be performed on any natural gas fueled motor vehicle nor on a transport tank, trailer or skid tank, whether empty or loaded, until reasonable precaution has been taken to provide the required safety.
(f) All repairs to natural gas tanks or vaporizers affecting the safety of such tanks or vaporizers shall be reported to the Division within 21 days by the qualified inspector authorizing such repairs. The qualified inspector shall stamp his certificate of competency number adjacent to all welded repairs authorized by him except that in the case of repairs to quenched and tempered steels, this number need not be stamped. This exception shall be noted in the inspector's report.
(g) Any welding necessary when making repairs or alterations to tanks, vaporizers or piping shall be done according to welding procedures and by welders qualified in accordance with the rules of Section IX of the ASME Code in the position or positions used in making the repair.
(h) Repairs to DOT cylinders shall be made under DOT regulations and control.
[FNa1] For Appendix A, refer to end of Subchapter 1.

s 527. Control of Products in Tanks and Cylinders.
(a) General. Natural gas contaminants such as hydrogen sulfide and water shall be so minimized as to prevent any adverse effects on storage and utilization equipment.
(b) Compressed Natural Gas.
No natural gas shall be delivered into any vessel or system covered by these Safety Orders unless odorized. The gas shall have a distinctive odor of sufficient intensity so that the presence of the gas may be detected down to the concentration in air of not over 20 percent of the lower explosive limit. Odorants in the concentrations used shall be:
(1) Harmless to humans.
(2) Non-toxic.
(3) Non-corrosive to steel, iron, brass or copper.
(4) Non-soluble in water to an extent greater than 2.5 parts by weight of odorant to 100 parts by weight of water.
(5) Be compatible with natural gas at the pressures and temperatures to be encountered in storage, transfer and service.
(c) Liquefied Natural Gas.
The delivery of LNG into any vessel or system covered by these Orders shall be subject to monitoring by a methane gas detection system, as follows:
(1) Each methane gas detection system required by this section shall provide a warning when an airborne methane gas concentration exceeding 20 percent of the lower explosive limit is detected. The warning shall be plainly audible and visible to those within the zone of potential exposure to fire or explosion of the vessel, system, or delivery operation.
(2) Where LNG is delivered into a vessel or system that is part of a motor vehicle, the methane gas detection system shall function continuously during the course of the delivery operation so that methane leaks resulting in an airborne concentration exceeding 20 percent of the lower explosive limit will be detected in the immediate vicinity of the operation.
(3) Where LNG is delivered to any other vessel or system covered by these Orders, the methane gas detection system shall function continuously during the course of the delivery operation so that methane gas leaks resulting in an airborne concentration exceeding 20 percent of the lower explosive limit will be detected in the immediate vicinity of the operation and the entire vessel or system into which the LNG is delivered. After delivery is completed, the methane gas detection system shall be operated continuously in the immediate vicinity of the entire vessel or system into which the LNG was delivered for as long as the vessel or system contains LNG.
(4) Nothing in this section is intended to supercede or alter the applicable requirements of 13 CCR Section 935.
[FNa1] For Appendix A, refer to end of Subchapter 1.

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

s 528. Transfer, Operation and Maintenance.
(a) General.
(1) No natural gas shall be vented to the atmosphere unless the vent is led to a safe point of discharge. Nothing in this Order shall prohibit the use of gaging devices which vent to the atmosphere through an opening not exceeding No. 54 drill size.
(2) No smoking or open flame shall be permitted within 10 feet of any vessel during the filling operation.
(3) All threaded filling connections shall be kept effectively capped when not in use. These caps or plugs shall be so designed that they will vent to the atmosphere while at least 3 full threads are engaged.
(4) No employer or employee shall charge natural gas into any tank or cylinder not specifically designed for the most severe pressure and temperature conditions to which the vessel may be subjected.
(5) During the transfer of natural gas at least one attendant familiar with the transfer operation shall be responsible for and be on the premises during the transfer operation. During the transfer of LNG the attendant shall remain in attendance at the controls necessary to stop the transfer operation. The attendant required by this Order may be considered familiar with the transfer operation after he has been provided with a set of instructions for the transfer operation and has performed the operation at least through 3 full cycles under supervision. When natural gas is being transferred to or from a motor vehicle, the engine shall be stopped unless the motor is used to operate a pump or compressor required to transfer the product. During such loading or unloading from transportation tanks, the hand or emergency brake of the vehicle shall be set and the wheels blocked. Transportation tanks shall be bonded during the transfer operation except that bonding is not required where the transfer systems are depressurized by bleeding before disconnecting, see Paragraph 537 (a) (4), and providing also that closed connections are made before transfer begins.
(6) No natural gas shall be transferred with the point of delivery less than 10 feet from any important building or house trailer, or within 5 feet from a sidewalk or public highway, street or road unless the failure to transfer would create a hazard. At the discretion of the Division, the point of delivery may be located a lesser distance from important buildings constructed of concrete or masonry materials. Nothing in this Order shall be so construed as to prohibit the following:
(A) The fueling of machinery or vehicles used in road construction or maintenance.
(B) The filling of motor fuel tanks or cylinders of not more than 30-gallon capacity.
(7) Pumps and compressors shall be suitable for use with the product to be handled for the full range of pressure and temperature to which they may be subjected. Positive displacement transfer pumps shall be equipped with a pressure actuated bypass valve and/or a recirculating system which shall limit the pressure to the maximum design pressure of the pump or piping system whichever is lower.
(8) Control devices shall be designed for the pressure, temperature and service expected and shall be so installed that icing conditions will not cause malfunction.
(9) The owner and/or user shall maintain all pressure vessels and their appurtenances, piping systems, vaporizers, controls and devices in a safe condition.
(10) A portable fire extinguisher having a rating of not less than 20BC shall be provided at the transfer operation area.
(b) Compressed Natural Gas.

(1) The pressure to which a CNG tank is charged shall not exceed the maximum allowable working pressure of the tank being filled at normal temperature. DOT cylinders shall be charged in accordance with DOT pressure and temperature regulations.
(c) Liquefied Natural Gas.
(1) To provide for the expansion of LNG with temperature, the tanks shall not be filled beyond the level specified by the tank manufacturer and in no case more than 90 percent.
(2) Tank fuel loading and unloading areas shall be substantially level.
[FNa1] For Appendix A, refer to end of Subchapter 1.

s 529. Gaging Devices for Liquefied Natural Gas Tanks.
(a) A permanent dip pipe shall be installed in all LNG tanks filled by volume and shall be of such length that it will indicate when the tank is filled to the level specified by the manufacturer and in no case more than 90 percent. This fixed dip pipe shall be permanently installed in the tank. Additional dip pipes may be used providing they are permanently marked to show the outage they indicate.
(b) In addition to the fixed dip pipe required in (a) above, each LNG tank 60- gallon capacity or more, filled by volume, and each motor fuel tank shall be equipped with a liquid level gage.
(c) Gaging devices that require bleeding of the product to the atmosphere shall be so designed that the maximum opening of the bleeder valve is No. 54 drill size.
(d) Gaging devices shall be designed for the most severe pressure and temperature conditions to which the device may be subjected with a factor of safety of not less than 4. Such gaging devices shall be labeled with the maximum permitted pressure by the manufacturer.
(e) Where the efficiency of the insulation of an insulated tank is dependent upon the vacuum in an annular space, an indicating device or other means shall be provided to warn of loss of vacuum.
[FNa1] For Appendix A, refer to end of Subchapter 1.

s 530. Approval of Devices.
(a) All devices which are used in natural gas installations shall be of a type and construction suitable for their intended use. The Division may approve or accept devices or package units upon satisfactory evidence that they are designed and constructed for safe operation in natural gas service.
(b) Except for control and indicating devices that are also designed for natural gas and which have an orifice not larger than No. 54 drill size, natural gas shall not be used to operate any device or equipment designed to be operated with compressed air which exhausts to the atmosphere. Natural gas vapor shall not be released into the air except as permitted by these Orders.
(c) All natural gas devices not otherwise specifically provided for shall be constructed and installed to provide safety equivalent to that required for other parts of the system.
(d) All electrical wiring and electrical equipment used with natural gas storage or dispensing apparatus shall be in accordance with the Electrical Regulations administered by the Division.
Note: For the purpose of this Order 530 (d), the electrical equipment installed in out-of-doors installations for stationary storage or the transfer of natural gas shall be suitable for use in a Class 1, Division 1, Group D hazardous location when installed within 10 feet in any direction of any connection used for the transfer of natural gas.
In order to comply with the "source of ignition" provisions of Order 531 (a) electrical switches, lamps, etc., located outside the above 10-foot area, but within the area specified in Order 531 (a) shall be suitable for use in a Class 1, Division 2, Group D, hazardous location. All electrical motors within this area shall be suitable for use in out-of-doors locations and shall be either:
(1) Of the explosion-proof type.
(2) Of a type having no contactors, commutators or sparking parts.
(3) Of a totally enclosed type.
[FNa1] For Appendix A, refer to end of Subchapter 1.

s 531. Location of Storage Tanks and Regulating Equipment.
(a) General.
(1) Except as provided elsewhere in these Orders, tanks, cylinders and regulating equipment used with natural gas storage and/or dispensing installations shall be located outside of buildings. Each individual tank or cylinder used for storage or dispensing natural gas shall be located with respect to the nearest important building, or line of adjoining property which may be built upon, or source of ignition, in accordance with the following table:

Capacity Per Storage ............................. Distance Between
Tank or Bank of .......... Minimum Distance Above Ground
Cylinders U. S. Gallons ...... In Feet Storage Tanks, Feet
To 500 .......................... 10 3
501 To 2,000 .................... 25 3
2,001 To 30,000 ................. 50 5
30,001 To 70,000 ................ 75 1/4 of Sum of Diameter
of Adjacent Tanks with
70,001 To 90,000 ............... 100 a Minimum of 5 Feet

Note: At the discretion of the Division, tanks may be located a lesser distance from important buildings constructed of concrete or masonry materials.
(2) No stationary storage vessel shall be located less than 10 feet from the nearest street line or sidewalk, nor less than 50 feet from the nearest rail of any railroad main track.
The distance between underground tanks shall be not less than 12 inches.
(3) Except as permitted in Section 543, filling connections shall not be located less than 10 feet from any opening into or under a building closed on more than 3 sides for filling connections 1/2-inch pipe size or less and 15 feet for larger sized filling connections.
(4) Readily ignitible material shall not be permitted within 10 feet of any stationary vessel or vaporizer.
(5) Regulators which are vented to atmosphere shall be installed in such a manner that moisture cannot enter the vent and accumulate above the diaphragm. Where the regulator vent may be obstructed due to rain, snow or icing conditions, shields, hoods or other suitable devices shall be provided to guard against closing the vent opening.
(b) Compressed Natural Gas.

(1) Multiple cylinder units or groups stored in the vertical position shall be limited to a width of no more than 4 cylinders. Units or groups stored in the horizontal position shall be limited to a height of 6 and a width of 4 cylinders. When stacked horizontally, the units or groups shall be separated by not less than 3 feet.
(2) No cylinder filling platform shall be located less than 10 feet from any storage tank, or 25 feet from the nearest important building or line of adjoining property that may be built upon. At the discretion of the Division, cylinder filling platforms may be located a lesser distance from important buildings constructed of concrete or masonry materials.
(c) Liquefied Natural Gas.
(1) All aboveground LNG tanks larger than 2,000 gallons shall have diked impounding areas or equivalent in accordance with Pamphlet 59-A of the National Fire Protection Association.
[FNa1] For Appendix A, refer to end of Subchapter 1.

s 532. Installation of Aboveground Storage Tanks.
(a) General.
(1) Storage tanks installed aboveground shall be installed on firm masonry or concrete foundations. Aboveground horizontal tanks shall have no more than 2 points of support longitudinally. Where necessary, tanks shall be securely anchored to prevent floating.
(2) Metallic structural supports, when used, shall be encased in concrete or other material having a fire resistant rating of at least 2 hours when the distance between the lower surface of the tank and the top of the concrete or masonry foundations exceeds 18 inches. In the case of a vertical tank having no more than one opening in the support skirt, interior fire protection of the skirt may be omitted. (Tanks of not more than 575-gallon capacity installed in areas having an average snowfall exceeding 18 inches may, at the discretion of the Division, be exempt from the provisions of this paragraph.)
(3) Every tank shall be so supported as to prevent the concentration of excessive loads on the tank at the points of support. All foundations and fastenings shall be designed to provide reasonable safety under all imposed loads including wind, earthquake, vibrations, etc. All tanks over 1,200 gallons capacity shall be installed on foundations in such a manner as to permit expansion and contraction.
(4) The valves and other appurtenances on tanks at all bulk plants, if the plant is not otherwise fenced, shall be surrounded by a rugged steel fence or equivalent. Fences which are not of an open mesh type may be used providing they are acceptable to both the local fire department and the Division. The fence required by this Section shall be at least 6 feet in height. Any fence completely surrounding the tank shall be located a minimum distance of 3 feet from the tank. Other tanks shall also be surrounded by a rugged steel fence or equivalent, if in the opinion of the Division a fence is needed to prevent unauthorized tampering. All fenced areas shall be kept locked when unattended.
(5) Aboveground storage tanks shall be protected from impact from trucks, trailers and other vehicles, where such impact is likely or probable, by suitable curbs, fences or posts and railings. Such curbs or fences shall be arranged so that they will not hamper free ventilation around the tanks.
(6) All loading and unloading connections at bulk plants shall be secured to a concrete bulkhead or equivalent designed to withstand the load imposed by the strongest pipe, hose or flexible metal hose, and fittings to be used in the transfer operation without breaking, or 2,000 pounds whichever is greater unless other adequate protection is provided. This bulkhead shall not be located underneath the tank. The loading and unloading connections shall be firmly secured to this bulkhead and the line between the bulkhead and tank shall be installed in a manner to provide for expansion, contraction, jarring, vibration and settling. Such bulkhead shall be located no less than 25 feet from the nearest important building or line of property adjoining that may be built upon. When in the opinion of the Division such bulkhead is necessary for the safety of the place of employment, it shall be required at storage plants other than bulk plants mentioned above.
(7) The fill line on storage tanks shall be equipped with a back-flow check valve to prevent discharge of the natural gas from the receiving tank in case of line, hose or fittings rupture.
(8) A fire extinguisher conforming to the provisions of California Administrative Code, Title 19, Chapter 1, Subchapter 3, and having a rating of not less than 20B shall be available and ready for use during the time natural gas is being transferred. The extinguisher carried on a bulk delivery or transportation vehicle may be considered as meeting the requirements of this Order when transferring natural gas from or to such vehicle provided the extinguisher has the required rating listed above.
(b) Compressed Natural Gas.
(1) When the tank is installed directly on concrete or masonry foundations, a corrosion pad shall be provided at the points of contact with the foundation. These corrosion pads shall be at least 3/16-inch thick, and have a width at least equal to the width of the foundation at the point of contact with the tank, but in no case shall they be less than 8 times the shell thickness in width. When corrosion pads or pad-type steel supports are used, the pads shall have corners rounded to a radius of not less than 6 times the pad thickness, and shall be attached to the shell with a continuous seal weld. These pads shall be not less than 1/4 the circumference of the shell in length.
(2) Pressure vessels which are made of materials that are subject to corrosion by atmospheric conditions and which are not provided with an allowance for external corrosion by a suitable increase in the design thickness shall be protected by painting or other equivalent means necessary to check active corrosion.
(3) Cylinders used at dispensing stations shall be installed on firm concrete or masonry foundations and located in accordance with 531 (a) and (b).
(c) Liquefied Natural Gas.
(1) Supports for LNG tanks shall be designed to withstand low temperature effects of LNG spillage.

(2) LNG tanks installed in battery shall be so installed that the 90 percent outage levels or the top surfaces of the tanks are substantially in the same horizontal plane.
(3) Tanks installed in battery shall not be installed with liquid and/or vapor lines connecting into common headers unless either:
(A) The working pressure of all such tanks is the same.
(B) Check valves or other devices are installed in the system to prohibit the introduction of the higher pressure product into the lower pressure tank.
[FNa1] For Appendix A, refer to end of Subchapter 1.

s 533. Location and Installation of Underground Tanks.
(a) General. Tanks and regulating equipment shall not be buried below ground unless written permission to do so has been obtained from the Division and the following special conditions are complied with:
(1) The proposed location complies with Order 531 (a) (1), (2) and (3).

(2) The tank shall be set with the top at least 24 inches below the surface of the ground, shall rest on firm foundations and shall not be installed under roadways.
(3) Before any back-filling is done, the installation shall be inspected by a qualified inspector and shall comply with all applicable sections of these Orders.
(4) The back-filling shall be done in such a manner that there will be at least 6 inches of water-washed sand free from soil, rocks or gravel immediately adjacent to the tank. The sand shall be well tamped into place during the back-filling operation.
(5) All buried tanks shall be constructed for underground service and the manufacturer shall provide means for lowering the tank into place without damage to the tank or corrosion-resistant coating.
(6) If the valves and fittings are located in a curb box, adequate provision shall be provided for proper drainage and ventilation of the curb box.

(7) No curb box shall be larger than necessary for the operation and maintenance of the valves and fittings located therein nor more than 3 feet in depth.
(8) All buried tanks shall be completely uncovered for an inspection of all external surfaces at intervals of at least once every 3 years.
The intervals may be changed at the discretion of the Division if a test plate is buried adjacent to the tank and shows no appreciable corrosion on inspection after 3 years of service; provided, however, that every tank shall be uncovered at least every 15 years. The test plates shall be of the same material as the shell of the tank and shall be at least 1/4 of the tank diameter in length and 6 inches wide and shall be buried in water-washed sand at least as deep as the lowest surface of the tank, and shall not be coated. Test plates shall be provided in accordance with the following table:
(A) Tanks 10 feet or less in length, one test plate.
(B) Tanks more than 10 feet but less than 20 feet in length, 2 test plates, one on each side near opposite ends.

(C) Tanks 20 feet or more in length, one test plate for each 10 feet of length, placed on alternate sides at 10-foot intervals.
(9) No tank used underground shall be reinstalled aboveground until it has been inspected and found to be in compliance with requirements for an aboveground installation.
(10) Where necessary, tanks shall be securely anchored or weighted to prevent floating.
(b) Compressed Natural Gas.
The exterior surfaces of CNG tanks shall be covered with an acceptable corrosion-resistant material.
Tanks will be considered acceptable when prepared and coated as follows:
(1) Clean and prime.
(2) Coat with asphalt enamel.

(3) Wrap with 40-pound felt.
(4) Coat with asphalt enamel.
(5) Wrap with 40-pound felt.
(6) Coat with asphalt enamel.
(7) Wrap with Kraft paper.
Equivalent corrosion protection may be accepted at the discretion of the Division.
(c) Liquefied Natural Gas.
(1) LNG vessels utilizing a vacuum jacket shall be so installed that a vacuum leak can be detected, and so piped that means can be provided to restore the vacuum or minimize the leak.
(2) Consideration shall be given to the design and installation of the supporting members and surrounding materials in the possible freezing zone to prevent damage to the tank and its supports by low temperature effects of LNG spillage or by frost-heaving.
(3) LNG vessels having an outer jacket made of a material which may be subject to corrosion shall be protected in accordance with (b) above.
[FNa1] For Appendix A, refer to end of Subchapter 1.

s 534. Skid Tanks.
(a) Skid tanks shall be securely fastened to skids extending the full length of the tank, including fittings and guards at the end of the tank. The bottom of the skids shall be not less than 2 inches nor more than 12 inches below the outside bottom of the tank shell. The skids or lugs for attachment of the skids shall be secured to tanks in accordance with the Code or rules under which the tank is designed and built, and shall be designed to withstand the loaded weight of the tank in any direction with a factor of safety of at least 8.
(b) Fittings on skid tanks shall be installed in a recessed well or otherwise protected by means of adequate guards properly installed.
(c) Unless installed in compliance with Order 532, skid tanks shall not be used at any location for more than 180 days without written permission from the Division.
(d) When skid tanks are transported from one location to another, they shall be adequately secured to the transporting vehicle.
[FNa1] For Appendix A, refer to end of Subchapter 1.

s 535. Installation of Tanks on Transportation and Bulk Delivery Vehicles.
Transportation tanks shall comply with the regulations for such vehicles adopted by the Department of Highway Patrol.
[FNa1] For Appendix A, refer to end of Subchapter 1.

s 536. Piping Standards.
(a) General.
(1) All pipe, tubing, fittings and other piping components between the tank and the first shutoff valve shall be designed for the full range of pressures, temperatures and loadings to which they may be subjected with a factor of safety of at least 8 based on the minimum specified tensile strength at room temperature. All other pipe, tubing, fittings and other piping components shall be suitable for the full range of pressures, temperatures and loadings to which they may be subjected with a factor of safety of at least 4. In no case may underground piping be less than Schedule 80 for piping systems having a working pressure exceeding 100 psi. Any material used, including gaskets and packing, shall be compatible with natural gas and its service conditions.
(2) All piping and tubing shall be run as directly as practical with adequate provisions for expansion, contraction, jarring, vibration and settling. Exterior piping may be either buried or installed aboveground and shall be well supported and protected against mechanical damage.
Underground piping shall be buried not less than 18 inches below the surface of the ground unless otherwise protected. All underground piping shall be protected from corrosion by coating in compliance with Section 533 (b) or equivalent. Zinc coatings (galvanizing) shall not be considered adequate protection for piping below ground.
(3) All welded piping shall be fabricated and tested in accordance with the ANSI Code for Pressure Piping, Petroleum Refinery Piping, B31.3, 1966 Edition or equivalent.
(4) All valves shall be suitable for the full range of pressure and temperature to which they may be subjected. The manufacturer shall stamp or otherwise permanently mark the valve body to indicate the service ratings. Other piping components such as strainers, snubbers and expansion joints shall also be permanently marked by the manufacturer to indicate the service ratings. All materials such as valve seats, packing, gaskets, diaphragms, etc. shall be resistant to the action of natural gas under the conditions to which they are subjected.
(5) Use of the following is prohibited:
(A) Valves, cocks, fittings and other piping components of cast iron or semisteel other than ASTM Specifications A-536-67, Grade 60-40-18; A-395-68; A-47-68, Grade 35018 and A-445-66 unless they have pressure-temperature ratings at least equal to 1 1/2 times the design service conditions. In no case shall valves of cast iron or semisteel other than the 3 ASTM specifications listed above be used for primary stop valves.
(B) Street ells and screwed service tees.

(C) Valves of a design that will allow the valve stem to be removed without removal of complete valve bonnet or disassembly of the valve body.
(D) Plastic pipe, tubing, hose and fittings, without written permission from the Division.
(E) Valves with valve stem packing glands which cannot be repacked under pressure, unless there is another stop valve of acceptable type between them and the vessel. This does not apply to service valves.
(F) Aluminum tubing for exterior locations and threaded aluminum connections and adapters that are required to be connected or disconnected as part of the filling or transferring operation except for those connections and adapters that are specifically designed with special threads suitable for this service.
(G) Pipe nipples in lieu of couplings or flanges in tank connections.
(H) Copper alloy with copper content exceeding 70 percent.
(b) Compressed Natural Gas.
Hose shall not be used in lieu of manifolds, piping or tubing between dispensing tanks and cylinders and the connection for the loading and/or unloading hose connections, except that a section of metallic hose not to exceed 24 inches in length may be used in each pipeline to provide flexibility where necessary. Each section shall be so installed that it will be protected against mechanical damage and be readily visible for inspection. The manufacturer's identification shall be retained in each section.
(c) Liquefied Natural Gas.
(1) Flanged joints or threaded joints which have not been seal welded on liquid lines between the tank and the first shutoff valve are prohibited.
(2) All LNG piping over 2-inch pipe size shall be welded, flanged or silver brazed with a material having a melting point exceeding 1,000 degrees Fahrenheit. Compression type couplings and threaded joints shall not be used except that seal welded threaded joints may be used.
(3) Piping 2-inch or smaller may be threaded, welded or flanged except as prohibited in 536 (c) (1).

(4) Threaded nipples and pipe shall be at least Schedule 80.
(5) Plugs shall be solid or else they shall be bull plugs of at least Schedule 80 seamless pipe.
(6) For service temperatures of minus 20 degrees Fahrenheit or above, threaded piping and tubing with compression type couplings may be used except as prohibited in 536 (c) (2).
(7) Pipe supports for piping having a service temperature below minus 20 degrees Fahrenheit shall be designed to minimize heat transfer so that support steel embrittlement and piping restraints caused by ice formation will be prevented.
(8) Bellows type expansion joints in low temperature service shall be provided with external insulation that will prevent ice from forming on the bellows.
[FNa1] For Appendix A, refer to end of Subchapter 1.

s 537. Piping Systems Valving and Labeling.
(a) General.
(1) All piping and tubing shall be tested after assembly and proved free from leaks at a pressure equal to the maximum working pressure of that portion of the system or its safety valve setting, whichever is greater, except for welded piping [see 536 (a) (3)].
(2) Where excess-flow valves are used, the closing flow shall be less than the flow rating of the piping system between the excess-flow valve and the equipment downstream of the excess-flow valve.
(3) When two or more vessels, other than motor fuel tanks or cylinders, are manifolded together or when branches or restrictions are incorporated into the piping system, additional excess-flow valves or equivalent shall be installed where the flow rating of the piping is less than the closing flow rating of the excess-flow valves in the vessels. The additional excess-flow valves or equivalent shall be located as close to the point of branching or restriction as possible.
Note: A quick-closing manually operated valve may be considered equivalent to an excess-flow valve at the point of pipe size reduction or other restriction providing:
(1) It is equipped with a means for closing the valve manually from a point remote from the delivery connection.

(2) The loading and/or unloading line in which it is located is secured to a bulkhead complying with Section 532 (a) (6).
(3) The quick-closing valve is in the pipeline on the tank side of the bulkhead.
(4) Bleed connections shall be provided in transfer systems to permit depressurizing the line before disconnecting. These bleed connections shall discharge at a safe place.
(5) Piping, compressors, pumps, valves, regulators, gaging and other vessel accessory equipment shall be protected against physical damage, including vehicular.
(b) Compressed Natural Gas.
(1) Except for safety relief valves and gaging connections all vessel connections, other than in motor fuel tanks or cylinders, larger than 1/4 inch pipe size shall have one of the following installed directly in each connection:

(A) A back-flow check valve to prevent flow from the tank.
(B) An excess-flow valve.
(2) A manually operated shut-off valve shall be installed as close to the vessel as practicable. Manually operated shut-off valves for DOT cylinders shall be provided in accordance with DOT regulations.
(3) Piping systems shall be protected against overpressure by safety relief devices. Relief devices installed to protect the piping system shall have sufficient capacity and shall be set to open at a pressure not exceeding 110 percent of the maximum allowable working pressure of the system or the pressure which produces a hoop stress of 75 percent of the specified minimum yield strength, whichever is lower.
(c) Liquefied Natural Gas.
(1) Except for safety relief valves and gaging connections all vessel connections, other than in motor fuel tanks, larger than 1/2-inch pipe size shall have one of the following installed directly in each connection (for the purpose of this Section tank connection location for double wall cryogenic vessels may be the point of penetration through the outer vessel or its jacketed extension):
(A) A back-flow check valve to prevent flow from the tank.
(B) A manually operated internal valve equipped with a means for closing the valve from a point remote from the delivery connection. The closing mechanism or its control shall be fitted with a fusible link having a melting point of 200 degrees Fahrenheit to 250 degrees Fahrenheit which will cause the valve to close automatically in case of fire.
(C) Either an internal valve which can be operated manually and will close on excess-flow conditions or one which is normally closed and is opened by pump discharge pressure. These valves shall be equipped with a means for closing from a point remote from the delivery connection and the closing mechanism shall be fitted with a fusible section as required in (B) above.
(D) An excess flow valve. In addition, there shall also be a quick closing automatic valve located as close to the tank as possible and which shall remain closed except during transfer. This valve shall be equipped with a means for closing automatically from a point remote from the delivery connection and shall be fitted with a fusible section having a melting point of 200 degrees Fahrenheit to 250 degrees Fahrenheit which will cause the valve to close in case of fire. Piping and valves shall be of austenitic stainless steel as listed in ANSI Code For Pressure Piping, B 31.3 1966 Edition, Table 302.3.1.A. Piping between the tank and the valve inlet shall be seamless and at least Schedule 40. All joints in the piping to and including the valve inlet shall be welded in accordance with 536 (a) (3).
(2) (A) Systems installed in accordance with (A) or (B) above shall have a manually operated shut-off valve located as close to the tank as practicable. Systems installed in accordance with (D) above shall have a manually operated shut-off valve located between the quick-closing automatic valve and the vessel.
(B) Systems with tank connections installed in accordance with (C) above shall have a manually operated shut-off valve located in the loading and/or unloading pipelines between the tank and the pump, meter or bulkhead whichever is nearest the tank.
(3) Wherever liquid can be trapped between two or more valves, a safety relief valve shall be installed to prevent excessive hydrostatic pressure. This safety relief valve shall start to discharge at not less than 125 percent nor more than 150 percent of the safe working pressure of the piping system between the two shut-off valves.
(4) All LNG tank connections having manually operated shut-off valves shall be labeled to indicate whether they communicate with the vapor or liquid space. At least one of the following methods shall be employed in labeling these connections:
(A) Tags of metal or other suitable material labeled "Liquid" or "Vapor." These tags shall be fastened securely to the tank, to the primary manual valve or to the piping system at the valve. The legibility of these tags shall be maintained.
(B) Complete color painting of all visible parts of the piping or its insulation.
(C) Color bands not less than 4 inches wide at each tank connection or primary manual valve. These bands shall be readily visible on the insulation. Where identification is provided by complete color painting or by color bands, a color code shall be posted where visible from the transfer operation.

[FNa1] For Appendix A, refer to end of Subchapter 1.

s 538. Hose, Metallic Hose, Flexible Metal Hose and Tubing Specifications.
(a) Hose and metallic hose shall be of or lined with materials that are resistant to corrosion and to the actions of natural gas.
(b) Hose, metallic hose, flexible metal hose and tubing shall be suitable for the most severe pressure and temperature service conditions expected with a burst pressure of at least 4 times the maximum working pressure. Flexible metal hose or pipe with swivel joints shall be used for transfer operations where operating temperatures during transfer will be less than minus 20 degrees Fahrenheit. (continued)