ASTM G91 is a standard practice for monitoring atmospheric SO2 deposition rate for atmospheric corrosivity evaluation. It provides a technical basis for tracking sulfur dioxide deposition in the environment, helping users understand conditions that may contribute to corrosion risk. By offering a consistent approach to this type of monitoring, the standard supports more reliable comparisons between locations, time periods, and exposure settings used in corrosion assessment and materials evaluation.

Purpose of ASTM G91

The purpose of ASTM G91 is to define a practical method for monitoring atmospheric SO2 deposition rate in support of atmospheric corrosivity evaluation. This makes it useful where environmental exposure conditions need to be characterized in a repeatable way. As an ASTM standard, it helps establish consistency in how deposition data are collected and interpreted, which can improve the quality of corrosion-related assessments and support more informed technical decisions.

Common use cases of ASTM G91

ASTM G91 is commonly used in atmospheric exposure programs, corrosion monitoring activities, and related quality control workflows where sulfur dioxide deposition is a relevant environmental factor. It may be applied when evaluating outdoor sites, comparing exposure severity, or supporting materials performance studies. The standard is especially relevant for users who need a structured way to document atmospheric conditions that can influence corrosion behavior over time.

Why ASTM G91 matters

ASTM G91 matters because consistent monitoring of SO2 deposition can reduce uncertainty in atmospheric corrosivity evaluation. Reliable data support better comparison of test locations, stronger documentation for compliance efforts, and improved confidence in corrosion assessments. For procurement, testing, and engineering teams, using a recognized ASTM standard can also help align methods across projects and improve the credibility of results used in product evaluation or risk reduction.

• Atmospheric SO2 deposition monitoring
• Corrosivity evaluation support
• Repeatable environmental data collection
• Exposure site comparison
• Corrosion assessment documentation