How To Manage and Reduce Hazmat Storage Risks

Whether you have chemicals that are the virgin constituents of a process, the useful byproducts of that process, or its hazardous waste, improper storage can result in a fire or explosion—along with all the legal, financial, and public-relations ramifications thereto. This blog entry discusses basic safety requirements for chemical storage. Q&As include:

1. Why can’t certain chemicals be stored next to one another?
2. How are chemicals grouped?
3. What are the storage requirements for Flammables & Combustibles?
4. What are the storage requirements for Volatile Poisons?
5. What are the storage requirements for Oxidizing Agents?
6. What are the storage requirements for Organic & Mineral Acids?
7. What are the storage requirements for Liquid Bases?
8. What are the storage requirements for Liquid Oxidizers?
9. What are the storage requirements for Non-Volatile Poisons?
10. What are the storage requirements for Metal Hydrides?
11. What are the storage requirements for Dry Solids?
12. What are some general dos and don’ts for storing chemicals?
13. What are the five most common and serious hazardous materials storage risks?
14. Where can you get comprehensive advice about hazmat storage safety?

1. Why can’t certain chemicals be stored next to one another?

In a word: reactivity.

Because otherwise benign chemicals can be hazardous in the presence of one another, the EPA has stringent regulations about inventorying, managing, handling, and storing them.

Perhaps you have diligent employees who think it neat and tidy to store chemicals nearby one another, arranged in alphabetical order, so that everyone knows which is what, exactly where it is, and all at a moment’s notice.

At first blush, that might seem laudable. But such orderliness can result in a fire or explosion.

For example, while copper sulfide and cadmium chlorate might exist benignly next to one another on your inventory list, in real life they’ll violently explode so juxtaposed.

Ditto for hydrogen peroxide (conveniently listed under H) and iron sulfide (logically listed nearby under I). While they get along well enough together on an Excel® spreadsheet, they react violently to one another up-close & personal.

Something else to consider—chemical groups react with other groups. For example, oxidizers, (of course) give off oxygen, making the ambient air more supportive of combustion. Thus, storing flammable materials nearby is asking for trouble.

2. How are chemicals grouped?

OSHA segregates chemicals into nine groups according to the UN Globally Harmonized System of Classification and Labeling, which was developed to standardize the classification and labeling of chemicals in order to augment their safe handling, transportation, and use worldwide. These groups are:

1. Flammables & Combustibles (See Q.3)
2. Volatile Poisons (See Q.4)
3. Oxidizing Acids (See Q.5)
4. Organic & Mineral Acids (See Q.6)
5. Liquid Bases (See Q.7)
6. Liquid Oxidizers (See Q.8)
7. Non-Volatile Poisons (See Q.9)
8. Metal Hydrides (See Q.10)
9. Dry Solids (See Q.11)

3. What are the storage requirements for Flammables & Combustibles?

Flammables & Combustibles are liquids that have flashpoints below 1000 F (38.780 C). So, the chief storage challenge is fire prevention. They should be kept in a cabinet designed specifically for flammables, or a refrigerator/freezer designed specifically to keep them below their flashpoints. Note: Flammables & Combustibles may be kept with Volatile Poisons (Group 2) or Liquid Bases (Group 5), but not with both simultaneously.

4. What are the storage requirements for Volatile Poisons?

Volatile Poisons include toxins and suspected carcinogens that have an evaporation ratio greater than 1.00, which essentially means that they evaporate into the air at a rate faster than butyl acetate, which is the standard. The chief storage challenge is that they’re a volatile poison when airborne and consequently inhaled. They require storage in a cabinet designed specifically for flammables, or refrigeration in containers of less than 1.06 quarts (1 liter). Note: Volatile Poisons can be stored alongside Flammables & Combustibles (Group 1), but only if bases are not present.

5. What are the storage requirements for Oxidizing Agents?

Oxidizing Acids require especially careful handling as all of them react robustly with one another, as well as with most other substances. The chief storage challenge is keeping them isolated in order to prevent the corrosion of whatever substance they inadvertently contact. They need to be stored in purpose-built safety cabinets, and each must be double contained (the primary container kept inside another, such as a canister, tray, or tub). Note: Small double‑contained quantities can be stored with Organic & Mineral Acids (Group 4) but must not be stored above them.

6. What are the storage requirements for Organic & Mineral Acids?

The chief challenge for storing organic and mineral acids is preventing contact and consequent reaction with bases and oxidizing acids, which corrode whatever substance they inadvertently contact. They need to be stored in purpose-built safety cabinets. Note: Small amounts of double-contained Oxidizing Acids (Group 3) can be stored in the same compartment with organic acids, if the oxidizing acids are stored below them. However, acetic anhydride and trichloroacetic anhydride are extremely reactive and should not be stored with Organic & Mineral Acids.

7. What are the storage requirements for Liquid Bases?

Just as acids must not come in contact with bases (see Q.5), the opposite is true. I.e., the chief storage challenge for liquid bases is preventing contact and consequent reaction with acids. Like acids, they can be stored in purpose-built safety cabinets. Unlike acids, they can otherwise be stored in tubs or trays in a regular cabinet. Note: Liquid Bases can be stored with Flammables & Combustibles (Group 1) if Volatile Poisons (Group 2) aren’t stored there.

8. What are the storage requirements for Liquid Oxidizers?

Liquid Oxidizers are particularly dangerous because they react with everything. Inadvertent contact will corrode surfaces and can even cause explosions. Thereby, the chief storage challenge is keeping them separated from all other substances. Quantities in excess of 3.17 quarts (3 liters) must be kept in a cabinet housing no other chemicals, although smaller quantities can be double-contained and stored near other chemicals. Otherwise: there are no compatible storage groups for liquid oxidizers.

9. What are the storage requirements for Non-Volatile Poisons?

A substance is deemed nonvolatile if it doesn’t readily evaporate into a gas. Nonetheless, one can be highly toxic and include known and suspected carcinogens, as well as mutagens. The chief storage challenge is preventing contact and consequent reaction between them and other substances. They should be stored in enclosed containers in a cabinet or refrigerator—and never on open shelves in a lab or cold room. Amounts in containers larger than 1.06 qt. (1 liter) must be stored with nothing below. Note: Non-volatile liquid poisons can be stored with non-hazardous liquids, except anhydrides (e.g., acetic and trichloroacetic acids).

10. What are the storage requirements for Metal Hydrides?

Metal hydrides react violently with water; some are even pyrophoric, igniting spontaneously in air. Thus, they pose a significant storage challenge, having to be isolated from all liquids and, in some cases, kept in a vacuum. They require storage in secure, waterproof, double-containment vessels; and they must be isolated from other storage groups. Note: If securely double-contained to prevent contact with water or air, metal hydrides can be stored nearby Dry Solids (Group 9).

11. What are the storage requirements for Dry Solids?

Dry Solids include all powders, whether hazardous or not. Those that are hazardous should be prominently labeled as such—and probably segregated, as well. The chief storage challenge is keeping them dry. Cabinets are recommended; open shelves are acceptable; but in either case, they should be stored above liquids. Note: It’s particularly important to store liquids below any dry solid containing cyanide or sulfide, as a spill would cause a reaction emitting poisonous gas. Metal Hydrides (Group 8) can be stored nearby dry solids in double containers, with the exception of solid picric or picric sulfonic acids, which can be explosive when exposed to shock or friction.

12. What are some general dos and don’ts for storing chemicals?

• Check regularly for spills, leaking containers, improper temperatures, etc.
• Dispose of expired chemicals, following hazardous waste removal rules.
• Ensure that all incompatible chemicals are segregated by hazard class codes.
• Label all chemicals with Material Safety Data Sheets (MSDS).
• Never store chemicals on the floor, nor any higher than eye level.
• Post appropriate signs (e.g., No Smoking, Flammable Liquids, Acids, Corrosives, Poisons, Chemical Storage, etc.).
• Shelves should be firmly anchored to walls and have anti-roll lips.
• Store like chemicals together, but away from others that might react if mixed.
• Store liquids in unbreakable or double-contained vessels, or in a storage cabinet that can contain the spill should the container fail.
• Use storage cabinets designed specifically for flammables.

13. What are the five most common and serious hazardous materials storage risks?

• Fire
• Explosion
• Sudden release of pressure (if a compressed tank is punctured)
• Reactivity
• Health hazards
• Environmental/community risks

14. Where can you get comprehensive advice about hazmat storage safety?

Don’t go it alone. The nuances of chemical storage—especially in the realm of hazardous waste management—require diligence on your part and that of your employees. As in all things involving the EPA—not to mention OSHA and a raft of state and local agencies—expert advice is crucial.

Get some here.