ASTM Materials 5 min read
ASTM B117 salt spray testing checklist: A Practical Compliance Guide
A practical, audit-ready guide to ASTM B117 salt spray testing, from solution preparation and chamber checks to specimen placement, monitoring, and reporting.
Why ASTM B117 Matters for Corrosion Compliance
ASTM B117 is the foundational practice for neutral salt spray testing. It describes how to operate the chamber, prepare the salt solution, and control temperature, fog collection, and pH. It does not tell you how long a coating must last or what amount of red rust is acceptable. Those acceptance criteria come from product specifications, drawing notes, or customer requirements. That distinction matters during audits: a lab can be fully compliant with ASTM B117 while a part still fails a project-specific corrosion requirement. ISO 9227 covers similar ground internationally, and ASTM G85 addresses modified salt spray cycles such as acidified or cyclic tests. If your supply chain requires material certificates, align the salt spray report with your broader ASTM material test certificate requirements.
Pre-Test Setup: The First Section of Your ASTM B117 salt spray testing checklist
A complete ASTM B117 salt spray testing checklist starts before the chamber door closes. The goal is to remove variables that can invalidate a run: contaminated water, incorrect salt, unstable air supply, or poorly prepared specimens. Document each check with a date, initials, and instrument reading.
Chamber and Apparatus Checks
Verify that the chamber is clean and free of previous salt deposits. Inspect the fog nozzle, baffles, and specimen racks for corrosion or blockage. Confirm the air supply is oil-free and that the saturation tower is filled and heated to the correct temperature. Check that the chamber drain operates freely and that no condensate can drip onto test specimens. Calibrate or verify the temperature controller, pressure gauge, and collection cylinders according to your quality system. If your organization follows ISO 9001, keep these records under document control.
Solution Preparation and pH
Prepare the salt solution with reagent-grade sodium chloride and water that meets the purity requirements of ASTM B117. The standard concentration is 5% ± 1% NaCl by mass. Measure pH after atomization, not just in the mixing tank, because dissolved gases and temperature can shift the reading. For neutral salt spray, the collected solution pH should be between 6.5 and 7.2. Adjust only with dilute hydrochloric acid or sodium hydroxide if needed, and record the adjustment. Do not use tap water unless it has been verified against the standard's limits for impurities.
Specimen Preparation and Placement
Specimen handling can make or break a salt spray test. Clean specimens so they are free of oil, grease, dirt, and temporary coatings. Use a method that does not alter the surface being evaluated. Mask cut edges or areas that are not part of the test if the product specification requires it. Record the cleaning method, masking materials, and any surface preparation steps.
Place specimens at 15° to 30° from vertical, with the tested surface facing the fog. Avoid shielding one specimen with another. Do not let specimens touch the chamber walls or each other. Arrange them so condensate runs off rather than pooling on the test surface. Support them with inert, non-metallic materials where possible. If the substrate is carbon steel such as ASTM A36, note that base metal composition can influence corrosion spread; see ASTM A36 chemical composition limits for context. For coated or packaged products, salt spray is only one part of the qualification story; distribution testing may follow a separate schedule such as the ASTM D4169 distribution testing schedule guide.
Operating Conditions and Monitoring
Once the test begins, monitor the variables that ASTM B117 controls. A typical daily check includes chamber temperature, solution concentration, collected solution pH, and fog collection rate. The chamber temperature for neutral salt spray is 35 °C ± 2 °C. The fog collection rate should be 1 to 2 mL/h per 80 cm² of horizontal collection area. Measure at least two collection points, and keep one near the specimens. If readings drift, correct the issue and document the deviation.
What to Record During the Run
Keep a log that includes:
- Date and time of each reading
- Chamber temperature
- Air pressure and saturation tower temperature
- Salt solution concentration
- Collected solution pH
- Fog collection volume and collection area
- Any interruptions, maintenance, or specimen observations
Do not open the chamber more than necessary. Each opening changes the fog distribution and temperature. If the test must be interrupted, record the duration and reason. ASTM B117 allows some operational flexibility, but the final report should show that the exposure environment stayed within the standard's tolerances.
Post-Test Evaluation and Reporting
At the end of the exposure, rinse specimens gently to remove salt deposits. Use running water or a gentle immersion, then dry them without scrubbing away corrosion products. Evaluate according to the acceptance criteria in the product specification, not ASTM B117 itself. Common evaluation methods include visual inspection, rust grade scales, coating blistering or adhesion checks, and mass loss measurements after descaling.
The report should identify the standard revision used, such as ASTM B117-19. Include specimen identification, surface preparation, test duration, chamber conditions, solution analysis, collection rate data, and any deviations. Attach calibration records for temperature, pressure, and pH instruments. If the customer requires a formal certificate, cross-check the report against your ASTM material test certificate requirements and keep the salt spray log with the test certificate.
Common Pitfalls and Audit Readiness
The most frequent problems are not exotic. They include contaminated water, pH measured before atomization, specimens touching each other, fog collection cylinders placed too close to the nozzle, and incomplete logs. Auditors also look for traceability: which chamber, which operator, which solution batch, and which calibration records. Use the ASTM B117 salt spray testing checklist as a living document. Review it when ASTM B117 is revised, when your quality system changes, or when a customer adds a new acceptance criterion. A controlled checklist reduces rework, supports repeatable results, and makes the difference between a test that merely ran and a test that can be defended.
Key facts
Machine-readable statements extracted from the sources above. Each fact keeps the same identifier across all six language versions.
35 °C ± 2 °C
Suhu kabinet kabut garam dijaga pada 35 °C ± 2 °C selama pengujian berlangsung.
Fact ID:
b117-chamber-temperature5% ± 1% (m/v)
Larutan garam dibuat dari NaCl grade reagen dengan konsentrasi 5% ± 1% massa/volume.
Fact ID:
b117-salt-solution-concentration6.5–7.2 (25 °C)
pH kondensat yang terkumpul untuk kabut garam netral berada pada rentang 6,5–7,2 saat diukur pada 25 °C.
Fact ID:
b117-collected-ph1–2 mL/h per 80 cm²
Laju pengumpulan kondensat adalah 1–2 mL per jam untuk setiap 80 cm² area pengumpulan.
Fact ID:
b117-condensate-collection-rate15°–30° from vertical
Spesimen dipasang miring 15–30° dari posisi vertikal di dalam kabinet.
Fact ID:
b117-specimen-angle< 1 µS/cm
Air yang digunakan untuk membuat larutan harus memiliki konduktivitas di bawah 1 µS/cm.
Fact ID:
b117-water-conductivity
Frequently asked questions
Does ASTM B117 define pass or fail criteria?
No. ASTM B117 is an operating practice for the salt spray apparatus. Pass/fail limits come from the product specification, drawing, or customer requirement.
What is the standard salt solution concentration in ASTM B117?
The salt solution is prepared at 5% ± 1% NaCl by mass using reagent-grade sodium chloride and water that meets the standard's purity limits.
What pH range is required for collected solution in neutral salt spray?
For neutral salt spray, the collected solution pH should be between 6.5 and 7.2. Measure after atomization because pH can shift during fog generation.
How long does an ASTM B117 salt spray test last?
ASTM B117 does not set a single duration. Exposure time is specified by the product or customer requirement, such as 96 hours, 240 hours, or 720 hours.
How does ASTM B117 differ from ISO 9227?
Both cover neutral salt spray testing. ISO 9227 is the international standard and includes additional salt spray test types, while ASTM B117 is widely used in North American supply chains.
Sources and licencing
Every claim in this article traces back to the sources listed below. Links open the publisher directly.
