Tank Linings

Caustic soda solution users are responsible for building and maintaining a properly designed storage and handling system which meets applicable safety and regulatory requirements. Each caustic soda solution user is responsible for determining which tank linings are suitable for its individual facility.

Tank linings are used to limit iron contamination and minimize corrosion. A caustic soda solution tank lining should be selected after careful consideration of process conditions and consultation with the lining material or system supplier. Some tank lining materials for consideration include nickel/nickel alloys, thermoplastics, resins, and elastomers.

Nickel/Nickel Alloy
Highly resistant to attack by caustic soda solution, nickel/nickel alloys are used where high purity product must be maintained or for storage temperatures above 160°F (71°C).

Thermoplastic
Many thermoplastics have excellent chemical resistance to caustic soda solution but have temperature limits that must not be exceeded. Materials such as polysulfone, and fluorocarbon resins (PFA, FEP, PTFE, ECTFE) are compatible with 50% caustic soda solution. Thermoplastics should not be used for a freestanding vessel. They should primarily be considered as a lining material.

Although other thermoplastics, such as PVC, CPVC, and polypropylene, are compatible with caustic soda solution, their use must be limited to lower concentration levels and temperature limits due to their maximum allowable useful temperature, e.g. CPVC: 120°F (49°C) and polypropylene: 200°F (93°C). Caustic soda solution heat of dilution must be considered when evaluating the maximum temperature limit of the vessel.

Resins
Epoxy resin formulations are used for tank, tank truck, and tank car liners for 50% caustic soda solution. Consult with the resin supplier for applicability for the specific conditions.

Elastomers
Some rubber materials, such as natural rubber, neoprene and chlorobutyl rubber, have been successfully used in limited applications. Consult the manufacturer for specific recommendations.

Silica-containing materials
Silica-containing materials, such as glass, brick and tile can be attacked by caustic soda solution and should not be used.

For additional information on caustic soda solution tank lining selection, review The Chlorine Institute, Inc. Pamphlet 094 "Sodium Hydroxide Solution and Potassium Hydroxide Solution (Caustic): Storage Equipment and Piping Systems." This pamphlet and additional resource materials can be purchased through the Chlorine Institute web site or send your request via fax to (703) 741-6068.

The information contained above is supplemental to the Internet Disclaimer and is not intended to be all-inclusive as it relates to use, handling, storage, disposal and all other described activities. Recipients must make their own determination of suitability and are responsible for compliance with all applicable federal, state, provincial, municipal laws and/or other regulations. This information is offered solely for your consideration and verification and in no event will The Dow Chemical Company be responsible for damages of any nature whatsoever resulting from the use or reliance upon this information or the product to which this information pertains.