Priming Buck tails

[daxmann]

Good Morning,

I'm currently in a discussion with other engineers and QA as to the requirement to prime a buck tail after a solid rivet has been driven. The rivets we use already come chemically treated and the area in question is not painted so I see no reason to prime the driven rivets. Does anyone on this site have an opinion on this?

 

[berkshire]

A lot here depends upon the surface treatment of the rivet as supplied. A bare rivet will not change its characteristics after being driven. however a large number of rivets are anodized although some are delivered with an Alodine chromate coating, the bucking enlarges and shortens the rivet cracking the anodic coating and giving a source for corrosion to start with Alodine the softer coating can scuff away during the bucking process . The usual treatment is to coat the driven rivet with primer or more Alodine to alleviate this.
B.E.

You are judged not by what you know, but by what you can do.

 

[Sparweb]

Someone may be out looking for problems that don't need to be solved. If the part doesn't need paint (and I assume not needing anodizing or any other surface treatment either) then the surface treatment that the rivet already has is plenty. Any corrosion that could attack the bucked head of the rivet (as BE suggested) can also attack the materials that are riveted together.
If you think you're going to lose the argument, see if using something like an alodine pen will mollify the inspector. Basically a bingo-dabber with alodine in it.

STF

 

[tbuelna]

In some cases if the correct grip length rivet is not available, it is permissible to trim a longer length rivet to the appropriate grip length. This will leave a bare surface on the rivet tail. But swabbing the upset end of the rivets with some primer does not seem like an unreasonable effort.

 

[daxmann]

Good advice guys, thanks.