BS ISO 21746:2019

What is ISO 21746 about?  

ISO 21746 specifies the testing method for galvanic corrosion of composites and metal assemblies subject to salt spray environment using a bonded or fastened specimen.  

Specifically, ISO 21746 provides guidance on the apparatus, the reagents and the procedure to be used in conducting the neutral salt spray (NSS), acetic acid salt spray (AASS) and copper-accelerated acetic acid salt spray (CASS) tests for assessment of the galvanic corrosion resistance of joints and bonded structures between carbon fibre reinforced plastics (CFRPs) and metallic materials, with or without permanent or temporary insulation for the galvanic current. 

Who is ISO 21746  for?  

ISO 21746 is beneficial to manufacturers of carbon fiber reinforced plastics (CFRP) and mettalic materials, and users such as high-tech manufacturers in a wide variety of industries such as aerospace, automotive, robotics, wind energy and mechanical engineering, amongst others. 

Why should you use ISO 21746?  

The potential benefits to CFRP-metal users of implementing a galvanic corrosion test based on ISO21746 are: 

• Addressing corrosion risks relating CFRPs of drastically nobler galvanic potential than metals to form a global cell between CFRP and metal  
• Expanding CFRP applications to the fields of corrosive environments that still require the combinations with metallic components 
• The detection or the prevention of galvanic current insulation loss, such as ion migration and time-related degradation in sealant film, injected calking layer and glass fibre reinforced plastics (GFRPs) layer 
• Demonstrating the conformity to specified conditions for type certification requirements in the engineering such as aircraft developments 
• Evaluating the corrosion related procedures for maintenance, repair and overhaul (MRO) in the engineering operations such of CFRP aircrafts. 

All of these benefits of ISO 21746 will help to ensure the quality and performance of carbon fibre reinforced plastics (CFRPs) in salt spray environments, throughout the supply chain to the end user.