Here's an overview:
: Concentrated acid absorbs atmospheric moisture instantly. If moisture enters a storage tank's headspace, a localized layer of diluted acid forms at the liquid-air interface. This diluted zone rapidly strips the passive iron sulfate layer, resulting in rapid pitting and severe localized wall thinning.
Includes information on high-temperature baked phenolic coatings and the use of plastics like PVC, PVDF, and polyethylene for specific concentrations. GlobalSpec Standard Evolution Original Issue: First prepared in 1991 as Major Revision: Revised in 2001 as RP0391-2001 Current Active Version: The standard was reaffirmed and renamed to SP0391-2016
) between 90% and 100% concentration by mass at ambient temperatures up to 50°C (120°F) . Originally compiled by NACE Task Group T-5A-18 and updated through the Association for Materials Protection and Performance (AMPP), this standard serves as a critical safety and mechanical reference for the chemical process industries (CPI). Managing concentrated sulfuric acid requires highly specific engineering controls due to its unique chemical anomalies, including extreme hygroscopic nature, exothermic dilution properties, and flow-velocity velocity effects.
: Because sulfuric acid is highly hygroscopic (it absorbs water from the air), storage systems must include desiccant dryers on vents to prevent the acid from diluting. Diluted acid (below 77%) is far more corrosive to carbon steel. 4. Comparison with Related Standards nace rp 0391 pdf
Some key aspects of NACE RP0391 include:
The most direct and legal way to obtain the official document is through the AMPP Store or via major standards providers like WRC Online Store .
for different concentrations of acid (e.g., 90%, 93%, 98%).
The standard emphasizes several design requirements to ensure long-term integrity: Here's an overview: : Concentrated acid absorbs atmospheric
Butt-welded and flanged piping are preferred over threaded connections to minimize turbulence.
: Tanks must be designed to minimize moisture ingress to prevent "hydrogen blistering" or thinning at the liquid-air interface. 2. Piping Systems
Concentrated sulfuric acid behaves paradoxically compared to diluted configurations. At lower concentrations, it acts as a strong reducing acid, aggressively attacking carbon steel. However, in the , it functions as an oxidizing agent and a powerful desiccant. The Protective Iron Sulfate Shield
This standard does not apply to acid concentrations below 90% or temperatures exceeding 50°C. GlobalSpec Key Technical Guidance Material Selection: aggressively attacking carbon steel. However
Sulfuric acid is one of the most widely used industrial chemicals globally, but its highly corrosive and reactive nature poses severe structural and safety challenges. This technical guide details how industrial systems safely implement this standard. Technical Overview and Document Evolution
Velocity must be kept low to avoid eroding the passive layer. Iron contamination can accelerate corrosion. 2. Materials for Piping and Valves
Determine if you need to compare this standard with international counterparts (e.g., ISO, DIN). NACE RP0391-91 | WRC Online Store
