Does my flammable liquid storage/processing require “explosion venting” design?

As I have said many times, OSHA’s 1910.106 is badly outdated, so for those who are looking for that extra edge to improve flammable liquids process safety (not just OSHA PSM/EPA RMP compliance, but real process safety), we should consider utilizing the 2018 International Fire Code (IFC). I should also point out that a fair number of states have or will soon be adopting this 2018 version, so for some of you, this may soon become “code” for your state. Until then, we should study these requirements closely and give serious consideration as this final layer of MITIGATION can mean a lot to a business that has suffered from an explosion. So what does the 2018 IFC require in terms of Explosion Control for areas storing, handling/ processing flammable liquids (I also cover combustible dust and gases) …

(emphasis by me)

SECTION 911 EXPLOSION CONTROL

911.1 General.

Explosion control shall be provided in the following locations:

1. Where a structure, room or space is OCCUPIED FOR PURPOSES INVOLVING EXPLOSION HAZARDS as identified in Table 911.1.

2. Where quantities of hazardous materials specified in Table 911.1 EXCEED THE MAXIMUM ALLOWABLE QUANTITIES in Table TABLE 5003.1.1(1)

Here are the applicable sections of TABLE 5003.1.1(1):

 

TABLE 5003.1.1(1) MAXIMUM ALLOWABLE QUANTITY PER CONTROL AREA OF HAZARDOUS MATERIALS POSING A PHYSICAL HAZARD

For SI: 1 cubic foot = 0.02832 m³, 1 pound = 0.454 kg, 1 gallon = 3.785 L. NA = Not Applicable, NL = Not Limited, UD = Unclassified Detonable.

1. For use of control areas, see Section 5003.8.3.
2. The aggregate quantity in use and storage shall not exceed the quantity listed for storage.
3. The quantities of alcoholic beverages in retail and wholesale sales occupancies shall not be limited providing the liquids are packaged in individual containers not exceeding 1.3 gallons. In retail and wholesale sales occupancies, the quantities of medicines, foodstuff or consumer products and cosmetics containing not more than 50 percent by volume of water-miscible liquids with the remainder of the solutions not being flammable shall not be limited, provided that such materials are packaged in individual containers not exceeding 1.3 gallons.
4. Maximum allowable quantities shall be increased 100 percent in buildings equipped throughout with an approved automatic sprinkler system in accordance with Section 903.3.1.1. Where Note e applies, the increase for both notes shall be applied accumulatively.

5. Maximum allowable quantities shall be increased 100 percent where stored in approved storage cabinets, day boxes, gas cabinets, gas rooms, exhausted enclosures or in listed safety cans in accordance with Section 5003.9.10. Where Note d applies, the increase for both notes shall be applied accumulatively.

6. Quantities shall not be limited in a building equipped throughout with an approved automatic sprinkler system in accordance with Section 903.3.1.1.

7. Allowed only in buildings equipped throughout with an approved automatic sprinkler system.

8. Containing not more than the maximum allowable quantity per control area of Class IA, Class IB or Class IC flammable liquids.

9. The maximum allowable quantity shall not apply to fuel oil storage complying with Section 603.3.2.

10. Quantities in parenthesis indicate quantity units in parenthesis at the head of each column.

11. A maximum quantity of 220 pounds of solid or 22 gallons of liquid Class 3 oxidizers is allowed where such materials are necessary for maintenance purposes, operation or sanitation of equipment where the storage containers and the manner of storage are approved.

12. Net weight of pyrotechnic composition of the fireworks. Where the net weight of the pyrotechnic composition of the fireworks is not known, 25 percent of the gross weight of the fireworks including packaging shall be used.

13. For gallons of liquids, divide the amount in pounds by 10 in accordance with Section 5003.1.2.

14. For storage and display quantities in Group M and storage quantities in Group S occupancies complying with Section 5003.11, see Table 5003.11.1.

15. Densely-packed baled cotton that complies with the packing requirements of ISO 8115 shall not be included in this material class.

16. The following shall not be included in determining the maximum allowable quantities: 1. Liquid or gaseous fuel in fuel tanks on vehicles. 2. Liquid or gaseous fuel in fuel tanks on motorized equipment operated in accordance with this code. 3. Gaseous fuels in piping systems and fixed appliances regulated by the International Fuel Gas Code. 4. Liquid fuels in piping systems and fixed appliances regulated by the International Mechanical Code. 5. Alcohol-based hand rubs classified as Class I or II liquids in dispensers that are installed in accordance with Sections 5705.5 and 5705.5.1. The location of the alcohol-based hand rub (ABHR) dispensers shall be provided in the construction documents.

17. Where manufactured, generated or used in such a manner that the concentration and conditions create a fire or explosion hazard based on information prepared in accordance with Section 104.7.2.

Here is Table 911.1, and as we can see that when the “control area” exceeds the amounts shown above (e.g. 120 gallons of a flammable liquid or any area that is determined to be a Class 2 HAZLOC), Explosion (Deflagration) Venting or Explosion (Deflagration) Prevention systems are REQUIRED.

1. Combustible dusts that are generated during manufacturing or processing. See definition of “Combustible dust” in Chapter 2.
2. Storage or use.
3. In open use or dispensing.
4. Rooms containing dispensing and use of hazardous materials where an explosive environment can occur because of the characteristics or nature of the hazardous materials or as a result of the dispensing or use process.
5. A method of explosion control shall be provided where Class 2 water-reactive materials can form potentially explosive mixtures.
6. Explosion venting is not required for Group H-5 Fabrication Areas complying with Chapter 27 and the International Building Code.

Such areas shall be provided with explosion (deflagration) venting, explosion (deflagration) prevention systems or barricades in accordance with this section and NFPA 69, or NFPA 495 as applicable.

Deflagration venting shall NOT be utilized as a means to protect buildings from detonation hazards.

 

911.2 Required deflagration venting.

Areas that are required to be provided with deflagration venting shall comply with the following:

1. Walls, ceilings and roofs exposing surrounding areas shall be designed to resist a minimum internal pressure of 100 pounds per square foot (psf) (4788 Pa). The minimum internal design pressure shall be not less than five times the maximum internal relief pressure specified in Item 5 of this section.
2. Deflagration venting shall be provided only in exterior walls and roofs. Exception: Where sufficient exterior wall and roof venting cannot be provided because of inadequate exterior wall or roof area, deflagration venting shall be allowed by specially designed shafts vented to the exterior of the building.
3. Deflagration venting shall be designed to prevent unacceptable structural damage. Where relieving a deflagration, vent closures shall not produce projectiles of sufficient velocity and mass to cause life threatening injuries to the occupants or other persons on the property or adjacent public ways.
4. The aggregate clear area of vents and venting devices shall be governed by the pressure resistance of the construction assemblies specified in Item 1 of this section and the maximum internal pressure allowed by Item 5 of this section.
5. Vents shall be designed to withstand loads in accordance with the International Building Code. Vents shall consist of any one or any combination of the following to relieve at a maximum internal pressure of 20 pounds per square foot (958 Pa), but not less than the loads required by the International Building Code:

5.1. Exterior walls designed to release outward.

5.2. Hatch covers.

5.3. Outward swinging doors.

5.4. Roofs designed to uplift.

5.5. Venting devices listed for the purpose.

6. Vents designed to release from the exterior walls or roofs of the building when venting a deflagration shall discharge directly to the exterior of the building where an unoccupied space not less than 50 feet (15 240 mm) in width is provided between the exterior walls of the building and the lot line.

Exception: Vents complying with Item 7 of this section.

7. Vents designed to remain attached to the building when venting a deflagration shall be so located that the discharge opening shall be not less than 10 feet (3048 mm) vertically from window openings and exits in the building and 20 feet (6096 mm) horizontally from exits in the building, from window openings and exits in adjacent buildings on the same lot and from the lot line.

8. Discharge from vents shall not be into the interior of the building.

 

911.3 Explosion prevention systems.

Explosion prevention systems shall be of an approved type and installed in accordance with the provisions of this code and NFPA 69.

911.4 Barricades.

Barricades shall be designed and installed in accordance with NFPA 495.