scope:

This standard establishes recommended practices to avoid caustic SCC of CS refinery equipment and piping. It addresses applications that use ¿fresh¿ caustic. Caustic SCC has been observed in the presence of contaminated caustic (especially contaminated with sulfide) in services that would otherwise fall within ¿area A¿ of the Caustic Soda Service Chart.

The practices detailed below are specifically intended for handling aqueous solutions containing sodium hydroxide (NaOH). However, several companies extend these practices to other strong alkali compounds (i.e., KOH and LiOH).

Some proprietary caustic solutions used in the industry (e.g., for carbon dioxide removal in hydrogen manufacturing units) contain inhibitors that may mitigate caustic SCC. In these cases, the practices included in this standard may be conservative. The effectiveness of any inhibitors added to industrial caustic solutions should be evaluated before the recommendations set forth in this standard are implemented.