ASTM B117 Testing Quality Control

ASTM B117 Testing

ASTM B117 Testing, also known as a Standard Practice for Operating Salt Spray (Fog) Apparatus, is used to analyze relative corrosion for specimens of metals and coated metals exposed to various simulated climatic conditions in a controlled environment. This testing practice was initially published in 1939 and rapidly gained worldwide acceptance across all major industry segments.

ASTM B117 Testing requires controls over many operational parameters such as:

• Fog atomization rate: 1.0-2.0 ml/hour
• Cabinet internal temperature 35 +/- 2 ^oC
• pH range: 6.5-7.2
• Salt concentration: 5 +/- 1%

If all of these parameters are set within the specifications, your corrosion tests should produce meaningful results.  However, it is an act of faith. At Micom, we always promote good laboratory practices and we test reference materials of known characteristics to insure that overall the test equipment is generating reliable test results. Such verification is possible for ASTM B117. Indeed in Annex X3 of the ASTM Document – “EVALUATION OF CORROSIVE CONDITIONS” a procedure is given “for evaluating the corrosive conditions within a salt spray cabinet”[1]. Furthermore ASTM B117 Document states “the procedure involves the exposure of steel test panels and the determination of their mass losses in a specified period of time.

Annex X3 specifies the test panels to be used with their dimensions and alloy grade (UNS G10080). It also includes a pre-test and a post-test chemical cleaning procedure for the panels. A total of 3 control panels are used for exposure durations of 48, 96 and 168 hours. Upon chemical cleaning and drying the panels are weighted to 1/10000^th of a gram (0,0001g). Annex X3 also contains repeatability and reproducibility statistics that can be used by laboratories as acceptance criteria for validating their salt spray testing cabinet.

These testing procedures allow testing labs to insure their test results are in line with the expected performance of a proper ASTM B117 testing protocol. Below you will find a reproducibility study done by our corrosion testing laboratory based on the ASTM B117, annex X3 requirements:

Reproducibility Study: ASTM B117 Testing – Operating Salt Spray (Fog) Apparatus