Q. Show the scope of materials used in caustic service?

This Engineering Practice presents metallic materials of construction commonly used in caustic service. The term 'Caustic' generally refers to Caustic Soda or Sodium Hydroxide (NaOH) but also includes Caustic Potash or Potassium Hydroxide (KOH). Corrosion of metals and nonmetals is generally considered the same for both NaOH and KOH. However, some indications show that KOH can be slightly more aggressive at elevated temperatures due to the higher boiling point.

This Engineering Practice does not cover every application particularly with respect to mixed streams. The user may wish to consult with the Materials Engineer or review previous inspection history as well as a thorough literature search.

Since this is an Engineering Practice, not a standard, it does not include specific material specifications. However, adherence to the types of materials of construction listed for the various temperatures and concentrations, is highly recommended.