: Historical, superseded iterations often found on archival download networks.
For areas where carbon steel fails or where high purity is required, is the premium choice.
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
The direct source. AMPP (The Association for Materials Protection and Performance) manages the NACE standards catalog.
) present significant engineering challenges due to its highly corrosive and hygroscopic nature. (formerly RP0391-91), often searched as "nace rp 0391 pdf," is the definitive Standard Recommended Practice for materials selection in these demanding environments. nace rp 0391 pdf
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.
: Specifically covers the design, fabrication, and inspection of sulfuric acid storage tanks.
NACE RP 0391 is a widely adopted standard in the oil and gas industry, providing guidelines for the cathodic protection (CP) of internal corrosion in steel pipelines. The standard, titled "Cathodic Protection of Internal Corrosion in Steel Pipelines," offers a comprehensive framework for designing, operating, and maintaining CP systems to mitigate internal corrosion in pipelines.
Butt-welded and flanged piping are preferred over threaded connections to minimize turbulence. : Historical, superseded iterations often found on archival
NACE RP0391 is essential for chemical engineers, storage facility operators, and corrosion specialists. By strictly adhering to the material selection, temperature limits, and contamination control measures detailed in this standard, organizations can maximize the life of their infrastructure and ensure safety in sulfuric acid handling. To get the most accurate and safe design, you may want to:
: Sulfuric acid is "thirsty"—it pulls moisture from the air. If the acid becomes diluted by atmospheric humidity, it loses its ability to form that protective iron sulfate layer and becomes much more aggressive toward the steel. ANSI Webstore The Engineer's Toolkit
This layer passivates the underlying steel and drops the uniform corrosion rate down to acceptable industrial levels (< 5 mpy / 0.13 mm/y). However, this protective layer is fragile and highly susceptible to mechanical disruption. Critical Engineering Risks
is a standard recommended practice 1.2.4 . It was developed to provide guidance on the selection of materials for tanks, piping, and related equipment. Original Publication: 1991 (NACE Task Group T-5A-18) 1.2.3 . Revision: 2001 (reaffirmed and revised to SP0391) 1.2.4. At lower concentrations, it acts as a strong
, titled "Materials for the Handling and Storage of Concentrated Sulfuric Acid at Ambient Temperatures," is a standard practice developed by NACE International (now part of AMPP: Association for Materials Protection and Performance).
NACE RP 0391 outlines several technical requirements to ensure the mechanical integrity of acid systems:
in pipelines and tank walls, as well as the effects of flow velocity on iron-based alloys. Protective Measures: Discusses methods like anodic protection