Sodium Hydroxide (Caustic Soda)   Sodium Hydroxide Tank .com
by Bailiff Enterprises
Sodium Hydroxide Bonding

Caustic Soda 50% - Tank Considerations and Storage Guidelines

  These are excerpts from Dow Chemical
... 3 facts that require special consideration about Caustic Soda 50% storage:
  • Caustic soda solution is highly corrosive and can be hazardous to personnel.
  • The viscosity of 50% caustic soda solution increases rapidly when its temperature falls below 65 °F (16 °C).
  • The weight of 50% caustic soda solution is 1.5 times that of an equal volume of water.
General Storage Guidelines for 50% Caustic Soda Solution:
  • Product should be stored between 85° to 100°F (29° to 38°C).
  • Over time, precipitation of calcium and magnesium hydroxide, carbonates and oxalates will occur.  A 2-4 year out-of-service tank cleaning schedule is recommended.
  • Tank discharge should be elevated at least 1 ft (30 cm) above the tank bottom to minimize entrainment of sediment.
  • A second tank discharge and a manway at the bottom of the tank for cleaning is recommended.
  • Tank inlet should be above the highest anticipated tank level with an inlet dip pipe, which extends below the lowest anticipated tank level to prevent splashing of the caustic soda solution.
  • Splashing or freefalling liquid, leaking pump suction gaskets, etc. will enhance additional carbon dioxide absorption resulting in the formation of insoluble sodium carbonate. These situations should be avoided.
  • Tank inlet should have a syphon break and be opposite the discharge line.
  • A 100% containment dike should be built around the storage tank.
  • It is recommended that an all Alloy-20 material of construction plug valve be used as the first valve on the tank.
  • A continuous tank level measurement device should be installed.  High level and overf
  • Redundant temperature sensors should be installed for temperature control.
  • High temperature alarms should be included.
  • Tanks should be vented to atmosphere and the vent line routed to within 3-feet (0.9 meter) of grade.  The vent line should include a syphon break.
  • Tanks and pipes should be insulated and traced to prevent the caustic soda solution from freezing.
  • The entire piping system should be free draining.
  • Electric heat tracing is recommended and preferred over steam tracing.
  • Aluminum, magnesium, zinc, tin, chromium, bronze, brass, copper, and tantalum are incompatible with caustic soda solution and must not be used for wetted parts used in equipment such as tanks, pumps, piping, instrumentation, etc.
  • Galvanized (zinc coated) materials should not be used in caustic soda solution storage and process areas.
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