: Broadly covers 90% to 100% commercial concentrated sulfuric acid. It does not apply to diluted acid concentrations below 90% or to oleum (fuming sulfuric acid containing free sulfur trioxide).
Originally developed in 1991 by NACE International (now merged into AMPP ), the standard was updated as and later reaffirmed as SP0391-2016 .
You can find the document listed as NACE Standard RP0391-2001 on the ANSI Webstore.
When dealing with highly corrosive substances, material selection is not just a design preference—it is a critical safety requirement. Among the most dangerous industrial chemicals is concentrated sulfuric acid (H₂SO₄). , now often referred to as NACE SP0391 (Standard Practice), is the benchmark document for managing this risk.
: Offers resistance at low temperatures, but can suffer rapid velocity-assisted corrosion if limits are exceeded.
Always check the revision history. The original has been superseded. The current version as of 2025 is AMPP SP0391-2018 (R2023) — the "R2023" means reconfirmed in 2023 with no technical changes.
: Updated and transitioned to a Standard Practice (SP) under AMPP (Association for Materials Protection and Performance) , which formed from the merger of NACE and SSPC. Scope Limits
Users seeking the official document can find it through authorized standards organizations:
For higher velocities, turbulence, or elevated ambient temperatures, advanced alloys are required:
The standard specifies that FRP pipes must consist of:
: The standard warns that turbulence—often caused by short-radius elbows or weld protrusions—is a leading cause of premature equipment failure.
