Spacing between process unit equipment and offsite storage tanks shall be a minimum of 60 m. For tanks exceeding 45 m in diameter, radiation calculations based on provisions in the Appendix, will be made for fire involvement of the full dike area to confirm that heat exposure from a dike area fire will not adversely affect the process equipment in the process units. Process unit grade level should be at least 0.6 m above adjacent tank area grade level. Locate low-pressure storage tanks downgrade and downwind of ignition sources in process units.
Offsite Tank Storage | Safety Considerations for Plant Layout Levels
The spacing from offsite storage tanks to substations, remote instrument enclosures, and control houses should be as follows:
a. For remote instrument enclosures, control houses, and for process unit substations:
(i) A minimum of 60 m from the tank shell and 30 m from the top of the dike for tanks greater than 12,720 m3 capacity and less than 45 m in diameter.
(ii) A minimum of 30 m from the tank shell and 15 m from the top of the dike for tanks less than 12,720 m3 bbl capacity and less than 45 m in diameter.
(iii) Crude storage should be spaced as far as practical from substations, remote instrument enclosures, and control houses.
(iv) For tanks over 45 m in diameter, see the Appendix.
(v) For central control houses see Paragraph 8.2.2.
b. For substations serving offsite storage areas only:
(i) A minimum of 30 m from the tank shell and 15 m from the top of the dike. Transformers may be located between the top edge of the dike and the substation.
(ii) For tanks over 45 m in diameter, see the Appendix.
(iii) Crude storage should be spaced as far as practical from substations, remote instrument enclosures, and control houses.
(iv) Consideration should be given to the potential consequences of exposing substations, remote instrument enclosures, and control houses to tank fires. The need to pump products during a fire, the potential loss of emergency shutdown, and potential business interruption should be considered.
Minimum spacing, between tanks and property lines, and between tanks and public ways shall be in accordance with NFPA 30, Chapter 2, with the following exceptions:
Access
a. Tanks, other than crude tanks, any diameter: Spacing between shells shall be a minimum of one-half the diameter of the larger tank.
b. Crude tanks any diameter: Spacing between tank shells shall be one and one-half diameter of the larger tank.
c. Hot oil tanks heated above 121 °C, excluding high-flash asphalt: Minimum spacing, shell to shell, shall be one and one-half times the diameter of the larger tank.
d. Slop oil emulsion-breaking tanks: Minimum spacing, shell to shell, shall be one and one-half times the diameter of the larger tank.
e. Low-pressure storage tanks shall be located at least 45 m to 60 m from other plant facilities, including process units and flammable liquid atmospheric storage tanks. These tanks shall be placed a minimum of 75 m from property lines or normally occupied buildings; from a flare, furnace, or similar
continuous ignition source; or from any fixed source of ignition. A refrigerated storage tank shall be installed at a distance of 1½ times its greatest dimension (diameter or height) but need not be more than 60 m from the line of adjoining property that may be built upon, as specified in API Std 2508 and API Std 2510. Refrigerated storage tanks of over 190 m3 shall be installed with a minimum spacing of at least half the diameter of the largest tank.
f. The minimum distance between adjacent low-pressure storage tanks shall be 15 m when they are protected by water spray or a system of water monitors. If the requirements of item (a) of this paragraph are met, water spray or deluge protection may be omitted.
g. Spare ISO containers in a storage area shall be kept 15m from adjacent units. Segregation of products within the storage area is recommended.
Tankage shall be arranged so that every tank with a diameter greater than 15 m is directly accessible from a fire fighting access road on at least one side. Tanks 45 m in diameter or larger shall be accessible from fire fighting access roads on at least two sides.
Tanks and Pipeway Protection
Pipeways shall not be routed through diked areas, except for product, utility, and foam piping to the tank. Grade should slope away at an angle of one percent beneath pipeways so that oil will not be contained in the immediate area. Sewer catch basins or drainage ditches shall not be located beneath
pipeways. When the grade is relatively slight, the pipeway shall be placed over a berm that is on a higher elevation than the adjacent area.
Pipeways shall be protected by installation of a fire resistant ditch cover or by a fixed water spray system at drainage ditch crossings. The fire resistant ditch cover, which may be a concrete culvert pipe, shall extend at least 9 m each side of the piping right-of-way. When a water spray system is provided, spray nozzles shall be located beneath the pipeway and shall be designed to provide a density not less than 20.4 (l/min)/m2) of the area beneath the exposed section of the pipeway.
Flanged or threaded joints and valves shall not be located over drainage areas that may contain oil due to a spill.
Fire seals, or fire stops, shall be installed in drainage ditches and pipe sleeper ways at 150 m to 215 m intervals and at roadway crossings to prevent the spread of fire. The seals shall be designed to skim the liquid surface to avoid trapping oil in the ditch.
Storage tanks with High Flash point Lube Oil
Storage tanks in high-flash lube oil service with flash points of 93 °C or higher and stored at ambient temperature should be spaced 30 m or more from process units, other refinery equipment, and refinery boundary limits.
Drainage and Dikes | Safety Considerations for Plant Layout Levels
High Pressure Storage Tanks and Spheres | Safety Considerations for Plant Layout Levels
Underground Storage Tanks | Safety Considerations for Plant Layout Levels