Materials for the Handling and Storage of Commercial Concentrated (90 to 100%) Sulfuric Acid at Ambient Temperatures

NACE SP0391-2016: Essential Guide to Materials for Concentrated Sulfuric Acid Handling and Storage

Professionals in the chemical processing, petroleum refining, and industrial manufacturing sectors regularly encounter the challenges of safely handling and storing highly corrosive substances. Among these, concentrated sulfuric acid (90-100%) presents unique material selection and design considerations. NACE SP0391-2016: Materials for the Handling and Storage of Commercial Concentrated (90 to 100%) Sulfuric Acid at Ambient Temperatures provides an authoritative and essential framework for mitigating the risks associated with this potent chemical. This industry-leading standard offers proven guidance to engineers and operations personnel, ensuring the integrity and safety of critical infrastructure.

What is NACE SP0391-2016?

NACE SP0391-2016 is a comprehensive standard practice developed by NACE International. It offers critical information specifically for the design and selection of materials used in the handling and storage of commercial concentrated sulfuric acid (H₂SO₄) at ambient temperatures, defined as up to 50°C (120°F). Its primary purpose is to empower engineers and maintenance personnel with the knowledge needed to make informed decisions, thereby enhancing the reliability and safety of concentrated sulfuric acid systems.

Scope & Purpose

This standard governs the selection of materials for equipment and systems involved in the handling and storage of sulfuric acid concentrations ranging from 90% to 100% by mass at ambient temperatures. It addresses aspects of design for static and low-velocity conditions, focusing on preventing accelerated corrosion. The standard does not cover sulfuric acid strengths outside this specified range, nor does it delve into high-temperature applications or the intricacies of oleum (sulfuric acid containing free sulfur trioxide).

Who Must Comply?

• • Primary Audience: Materials Engineers, Process Engineers, Chemical Engineers, Maintenance Engineers, and Operations Managers involved with sulfuric acid infrastructure.
• • Industries Affected: Chemical Processing, Petroleum Refining, Gas Processing, Industrial Manufacturing, and any sector utilizing concentrated sulfuric acid.
• • Compliance Nature: While NACE standards represent consensus best practices and are often adopted voluntarily, compliance is typically a recommended or required element in project specifications, insurance mandates, and regulatory frameworks, making it practically essential for safe operations.
• • Enforcement: Compliance is typically overseen by internal company quality assurance, safety departments, and potentially regulatory bodies during audits or inspections.

Key Requirements Overview

The standard provides essential guidance for professionals working with concentrated sulfuric acid. Key provisions include:

• • Material Suitability: It details the suitability of various materials, including carbon steel, for different components, emphasizing conditions under which carbon steel is acceptable (e.g., static or low-velocity flow) and highlighting its limitations due to potential localized attack.
• • Concentration and Temperature Limits: Professionals must adhere to the specified concentration range (90-100%) and temperature limit (up to 50°C) for which the material recommendations are valid.
• • Velocity Considerations: The standard stresses the importance of managing flow velocities to prevent turbulence and erosion-corrosion, particularly in piping and around fittings.
• • Protective Film Formation: Understanding how a protective sulfate film forms on materials like carbon steel is crucial, as is