Cadmium plating hi tensile studs
Cadmium plating hi tensile studs
(OP)
Hello everybody.
I wish to use cadmium plated hi tensile bolts and studs in a sub sea pipeline flange. I have previously used teflon coated but must have an alternative. Is hydrogen embrittlement an issue for Hi tensile cadmium coated fittings when used sub sea (55m) and cathodic protection applied?
Thanks
I wish to use cadmium plated hi tensile bolts and studs in a sub sea pipeline flange. I have previously used teflon coated but must have an alternative. Is hydrogen embrittlement an issue for Hi tensile cadmium coated fittings when used sub sea (55m) and cathodic protection applied?
Thanks





RE: Cadmium plating hi tensile studs
320 HV < core hardness < 380 HV: bake minimum of 4 hours at 200 +/- 5 C within one hour plating and before chromate treatment.
350 HV < surface hardness < 400 HV: same as above.
core hardness > 380 HV or surface hardness > 400 HV: bake minimum of 8 hours at 200 +/- 5 C within one hour of plating and before chromate treatment.
Since you did not list a fastener standard, I do not know what "hi tensile" means regarding the proper embrittlement relief. If the steel has been tempered at a temperature less than 200 C in order to attain the necessary mechanical properties, then the fasteners should be baked for a minimum of 8 hours at 115 +/- 5 C.
I would not recommend using cadmium plated bolts manufactured from medium carbon alloy steel for this type of application, especially if they are not produced to a proper fastener standard (ASTM, ISO, etc.). Nickel alloy or multiphase alloys (nickel-cobalt-chromium-molybdenum) perform much better in this type of environment, and with a suitable combination of cold working and heat treatment, can attain the necessary mechanical properties. I recommend you read the following article on multiphase fastener alloys from SPS:
http://www.spstech.com/aero/news/090602.html
They also have an excellent booklet on these alloys called Superalloys Developed by SPS Technologies for Aerospace Fasteners which you can obtain by clicking on the following link:
http://www.spstech.com/aero/prod_lit/index.html
RE: Cadmium plating hi tensile studs
http://www.avestapolarit.com/upload/documents/technical/acom/acom93_1.pdf
RE: Cadmium plating hi tensile studs
For info. contact Ron Saleker of Sifco Selective Plating 216-524-0099.
RE: Cadmium plating hi tensile studs
Zinc can too - the process is mechanical plating, rather than electroplating. If a member searched this website, and others, they would learn about cadmium vapor deposition, etc. There are numerous coatings, processes, vendors, info sources...
RE: Cadmium plating hi tensile studs
RE: Cadmium plating hi tensile studs
I would have concern about high strength materials in these applications, if you cannot find a way to prevent current from being applied after instalation. You might consider a way to cover the fasteners, to minimize any current reaching the fastener.