: 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 technique is often effective in mitigating corrosion and hydrogen grooving.
The standard emphasizes keeping temperatures below ) to prevent rapid corrosion. Prohibited Concentration: 100% H2SO4cap H sub 2 cap S cap O sub 4 nace rp 0391 pdf
: Originally published as a Recommended Practice (RP) by NACE International Task Group T-5A-18.
While NACE RP 0391 focuses on , it is often used in conjunction with other standards: : Sulfuric acid is "thirsty"—it pulls moisture from
NACE RP0391 (now officially NACE SP0391 ) is a technical standard titled "Materials for the Handling and Storage of Commercial Concentrated Sulfuric Acid at Ambient Temperatures". It provides critical guidelines for the design and material selection for systems managing 90% to 100% sulfuric acid ( cap H sub 2 cap S cap O sub 4 ANSI Webstore Key Technical Scope Concentration Range : Specifically covers concentrated sulfuric acid between 90% and 100% Temperature Range
Fe+H2SO4→FeSO4↓+H2↑Fe plus H sub 2 SO sub 4 right arrow FeSO sub 4 down arrow positive H sub 2 up arrow The standard emphasizes keeping temperatures below ) to
The primary objective of NACE RP 0391 is to provide a consensus-based framework for the and the design of equipment used to handle concentrated sulfuric acid.
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For higher velocities, turbulence, or elevated ambient temperatures, advanced alloys are required: