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Does zinc and clear passivate effect properties of high tensile screw?

Hello, we have had a failure in the field of a high tensile screw that has sheared halfway up the thread, this should not happen under the normal conditions/environment the product is in. Could the zinc and clear passivate process have weakened the thread in anyway,or could this just be a one off, freak occurrence?

Mark Greaves
QA engineer - Devon, England, UK
July 10, 2008

July 11, 2008

It certainly can if the post plate bake is not done properly or soon enough.
The sad part is that there are a number of reputable fastener companies that are accepting certifications from other low quality vendors as gospel. In the US, there are horror stories of aircraft quality fasteners that do not meet spec that are run thru several companies to obscure the junk status.
Several people are in jail for it.

James Watts
- Navarre, Florida

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