Keep Damage from Corrosive Liquids in Check!

By definition, corrosive liquids are hazardous. Aqueous liquids with a <2 or >12.5 pH are capable of corroding steel at a rate of more than 6.35 mm (0.250")/yr at a test temperature of 55 C. The fumes of these corrosives in the presence of humidity will condense predominately on metal surfaces. When the water evaporates, you are left with a very corrosive residue.

The first step toward keeping the damage from corrosives in check is a sound hazardous materials management program. This article addresses only the storage considerations.

Recommended practice:

• Store corrosives in a low-humidity, well-ventilated area.
• Store corrosives in properly sealed containers.
• Inspect containers regularly for damage.
• Store corrosives containers in cabinets on chemical-resistant trays to capture spills or leaks and promptly clean up any residue.
• Corrosives cabinets are typically vented only when required by the authority having jurisdiction. When venting, PVC is the preferred material.
• Connecting to an existing exhaust, such as a fume hood, is encouraged and may be required by the local jurisdiction.

Sound practice limits the amount stored on site to what is really needed. When possible, store in specially constructed corrosives cabinets. Amounts as small as two 4-L containers may be safely placed in countertop cabinets.

Safety cabinets should be selected for their durability and economics in regards to your application. It’s critical that incompatible chemicals be segregated to avoid disastrous reactions or fire. Depending on proper care, most cabinets will last a long time. Other considerations occur if you need a flammable liquid safety cabinet.

Five types of construction are available for corrosives safety storage cabinets:

• Double-wall steel
• Double-wall steel—combination flammable and corrosives
• Lined double-wall steel
• Molded polyethylene
• Wood with laminate finish

Double-wall steel cabinets with 1.5" air space incorporating dual vents, grounding connections, adjustable shelves, 3-point self-latching lockable doors and leveling feet are appropriate for corrosives that exhibit flammable characteristics. Corrosion protection is provided by molded spill-catching shelf-lining trays, which may be removed for cleaning. The steel cabinet is coated inside and out with a baked-on epoxy. The standard in the industry is a blue-colored finish for acids and bases. It has been exclusively formulated for chemicals commonly used in laboratories. Large iridescent, reflective labels identify the contents.

In some instances, double-wall steel combo cabinets may be used to store both flammables and corrosives. An inner double-wall partition with 1.5" air space segregates two independent 5-gal storage compartments. The corrosive side includes a removable polyethylene sump liner, and each compartment door is independently lockable. Large warning labels, yellow for flammables and blue for corrosives, clearly identify the contents. These cabinets are protected inside and out with a white epoxy powder coat finish.

Double-wall steel with a 100% seamless liner on all interior walls, ceilings, sumps, inside doors and shelves protects cabinet surfaces from rust and corrosion. The seam-free surface eliminates the need for rivets or any other metal fasteners with the accompanying risk of corrosion from seep-through chemicals. The non-porous surface resists staining, and spills can be cleaned easily.

A molded polyethylene design with no steel components may be applicable if the fire protection afforded by the double-wall steel cabinets is unnecessary. The chemically inert polyethylene material is impervious to the detrimental effects of harsh acids and other corrosive chemicals, and the benefit of removable polyethylene spill-catching trays is retained. This design also incorporates two vent openings with “removable caps” in the rear to accommodate pressurized vapor removal systems.

Wood cabinets with a laminate finish are the best for chemical durability. Long-lasting wood core construction provides exceptional strength, and stainless steel handles and hinges resist the corrosive effects of harsh acids and bases. The construction, however, does not meet the requirements for flammable liquids storage.

Remember to maintain low humidity, ventilate the area well, clean up spills promptly and store your chemicals in properly sealed containers. Maintained properly, any of these cabinets—steel, polyethylene or laminate—will keep damage from corrosives in check and serve the user well for years.