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Tankline Processes

Subject: Non-Chrome Anodize

Reference:
BAC 5019 Chromic Acid Anodizing, Revision T, 07-JUN-1999
BAC 5022 Sulfuric Acid Anodic Films, Revision H, 25-JUN-1991
BAC 5632 Boric Acid -- Sulfuric Acid Anodizing, Revision D, 03-AUG-04

Description of Problem:
Environmental laws in many areas encourage chrome free processes. The Boeing Company developed and qualified the Boric Sulfuric Acid Anodize process in 1990 as a chromic acid anodize replacement.

This information sheet is designed to provide comparative information between the referenced chrome and non-chrome anodize processes.

Process Comparison
Drawing and Specification Coverage for Boric Sulfuric Acid Anodize
Per BAC 5019 Section 1, Parts may be anodized in accordance with BAC 5632 Boric Acid -- Sulfuric Acid Anodize in lieu of BAC 5019 Chromic Acid Anodize, except when Class 4 is specified or when directed by drawing to chromic acid anodize in accordance with BAC 5019 only.

In addition, substitution drawings (ADCNs) exist for each commercial model (except the 717) which allow drawing callouts specifying BAC5019 (no class specified), BAC5019 class 1, BAC5019 class 3, or MIL-A-8625 Type 1 to be replaced by BAC5632 class 5 (unsealed) if all part surfaces will be painted.

Characteristic	Boric Sulfuric Acid Anodize (BSAA), BAC 5632, as compared to Chromic Acid Anodize, BAC 5019
Paint adhesion*	As good or better than chromic acid
Processing time	20 minute process 30-60% less time than chromic acid
Energy Requirements	Requires lower temperature and voltage more energy efficient than the chrome-based process
Facilities Requirements	Equipment may require material upgrade
Sealing	Dilute chromate seal must be used De-ionized water seal is not acceptable BSAA will take longer to reach the same extent of hydration as Chromic Acid
Bath Performance	Long term bath performance is more reliable
Licensing	BSAA requires patent license. No fee if all parts are for Boeing. Contact Boeing Intellectual Property Business
Other	In dusty environments, addition of sodium benzoate or benzoic acid to BSAA prevents fungus growth.

*The paint adhesion of unsealed anodize is better than with sealed anodize for Boric Sulfuric Acid Anodize or Chromic Acid Anodize.

BAC 5022 Sulfuric Acid Anodize

BAC5022 is not a suitable replacement for chromic acid anodize.
It produces a much thicker oxide which has a greater fatigue life reduction than the thinner oxides produced by BAC5632 or BAC5019.
It is generally called out for decorative purposes or when the anodize will be dyed for part identification.
The film growth rate is rapid and therefore the process must be tightly controlled (current density and time) to produce the desired film thickness.
The tank and piping must be resistant to the high concentration sulfuric acid (316L stainless for example).

Disclaimer:
The information provided in this website is intended to assist suppliers to The Boeing Company. Although every effort has been made to ensure its accuracy, we cannot warrant its accuracy for use in environmental compliance matters. You should check with your local, state, or Federal regulatory agencies if you have questions regarding the proper procedures or other matter related to compliance.

Safety Reminder:
Refer to Manufacturer's material safety data sheets, or contact the manufacturer for safety and health information pertaining to hazardous materials.

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