Concentrated sulfuric acid presents a unique paradox. While it is highly corrosive in general, at high concentrations (>90%) and ambient temperatures, it can actually form a protective iron sulfate film on certain materials, allowing them to be used safely. NACE RP0391 was created to define exactly which materials exploit this phenomenon and which fail catastrophically.
: "Ambient" temperatures are defined as those up to 50°C (120°F) , accounting for solar heating in tropical climates.
Note: For complete, actionable details on designing and fabricating sulfuric acid storage systems, it is recommended to pair this standard with . nace rp 0391 pdf
The industry workhorse for static storage. It relies on a protective ferrous sulfate ( FeSO4cap F e cap S cap O sub 4 ) film that forms naturally.
One of the standard's more specific warnings is about . This is a form of localized attack on vertical or inclined walls exposed to the liquid phase. It is caused by hydrogen bubbles evolving from the corrosion reaction, moving along the wall, and deteriorating the protective film, leading to deep grooves. To mitigate this, the standard recommends considering anodic protection for critical carbon steel vessels and piping. Concentrated sulfuric acid presents a unique paradox
: Technical standard stores like Accuris (formerly IHS) also provide the digital PDF.
The official NACE RP0391 Document Structure covers the entire life cycle of chemical handling systems: : "Ambient" temperatures are defined as those up
Because NACE standards are , the full text is generally not available for free through legal public repositories. You can obtain the official document through these channels:
