Cadmium plating of A325 bolts
Cadmium plating of A325 bolts
(OP)
We have been asked by a client to specify cadmium plated A325 bolts. I checked the ASTM Spec to see how to call that out, and it does not provide any information. I could not find any prohibition for cadmium plating of A325 bolts, but I also could not find anything that said it was permissible.
Can someone help with this matter?
Can someone help with this matter?





RE: Cadmium plating of A325 bolts
ASTM A 325 usually is specified plain or zinc coated (hot dipped galvanized, mechanical galvanized, inorganic Zn). You can learn more about specifying these types of fasteners here:
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You may want to just create your own drawings and specifications for this application. You can use ASME standards for the fastener geometry, and one of multiple ASTM standards for the material (e.g. ASTM A 325, A 354, A 574, or ...), although you may want to identify specific paragraphs rather than the whole standard.
For the cadmium coating, you can specify ASTM B 766 Standard Specification for Electrodeposited Coatings of Cadmium. Due to the potential for hydrogen embrittlement, you should review and specify one or more of the ASTM standards:
ASTM B 849 Standard Specification for Pre-Treatments of Iron or Steel for Reducing Risk of Hydrogen Embrittlement
ASTM B 850 Standard Guide for Post-Coating Treatments of Steel for Reducing the Risk of Hydrogen Embrittlement
ASTM F 326 Standard Test Method for Electronic Measurement for Hydrogen Embrittlement From Cadmium-Electroplating Processes
ASTM F 519 Standard Test Method for Mechanical Hydrogen Embrittlement Evaluation of Plating/Coating Processes and Service Environments
ASTM F 1624 Standard Test Method for Measurement of Hydrogen Embrittlement Threshold in Steel by the Incremental Step Loading Technique
ASTM F 1940 Standard Test Method for Process Control Verification to Prevent Hydrogen Embrittlement in Plated or Coated Fasteners
ASTM F 1941 Standard Specification for Electrodeposited Coatings on Threaded Fasteners (Unified Inch Screw Threads (UN/UNR))
RE: Cadmium plating of A325 bolts
There may be other structural bolting options.
http://www.FerrellEngineering.com
RE: Cadmium plating of A325 bolts
These are steel outdoor advertising structures. They are exposed to the weather for their entire lifetime.
RE: Cadmium plating of A325 bolts
http://www.FerrellEngineering.com
RE: Cadmium plating of A325 bolts
I did find out one of the reasons: typical galvanized bolts have been hard for their erectors to start by hand. The cadmium is easier for them to thread the nut.
RE: Cadmium plating of A325 bolts
Cadmium plating is outright banned in Europe, and is getting more and more hard to find in the US (and correspondingly more expensive). The materials used in the plating process are all considered hazardous waste material, and (proper) disposal is not cheap.
Sounds like the erectors are complaining about hot-dipped galvanized, as those can tend to have drips hardened onto the threads.
I'd suggest an electro-deposited zinc, possibly with a supplemental chromate conversion treatment. (although the chromate is not particularly environmentally friendly either).
There are a bunch of new organic platings available too.
RE: Cadmium plating of A325 bolts
RE: Cadmium plating of A325 bolts
RE: Cadmium plating of A325 bolts
But if your client has a specific concern with the bolts, I would probably suggest galvanized bolts.
http://www.FerrellEngineering.com
RE: Cadmium plating of A325 bolts