Corroded Rivet - Which ones do I replace 1

[BruceAus]

I'm working on a pedestrian bridge that have some 20,000 rivets of which 10% are corroded. The corroded rivets range from no head left to only a small amount of head missing. It is easy to decide what to do with those both ends of the spectrum, but how do I decided when where is the point where to much corrosion has occurred.

Does anyone have any guidelines on determining when a rivet should be replaced?

The next issue is a quick method to determine if a rivet passes or fails the guideline. I was thinking of some type of templates that you place over the rivet but as there are so many different possibility I not sure this would work. Anyone got any bright ideas on how this could be done?

 

[rowingengineer]

I assume you have worked out why these are corroding? How long it took for them to corrode? because if you’re just going to be back next month doing another 10% why not just do it once with a better spec rivet? You can get some 316 rivets and some other similar rivets that will do a good job in hard situations. Or maybe you can replace with 316 or aluminium screws ect.

To answer your first question we need to know the answer to the above question or you can't pin point where to look or investigate.


ANY FOOL CAN DESIGN A STRUCTURE. IT TAKES AN ENGINEER TO DESIGN A CONNECTION.”

 

[BruceAus]

The bridge is 70 years old and is in the process of being fully abrasive blasted and repainted.
Most of the rivets that are corroded have been in locations where they is higher humidity / moisture and the painting system has failed.
Aluminum or stainless is not a option due to galvanic corrosion.

 

[bridgebuster]

Aattached is an "unofficial" standard sheet that's been used on NYSDOT projects, as well as other public agencies in NY, for over 30 years that provides guidance on rivet replacement.


You can also download a report from the US Army COE. It's a finite element analysis method to determine when rivets need to be replaced.

Technical Report ITL-99-5
December 1999
Rivet Replacement Analysis

 

[bridgebuster]

BTW if you need a spec for rivet removal, down load NYSDOT Standard Specs, Item 586.05.

One thing to keep in mind - I'm sure you know this - particularly if you're working in a heavily traveled area: Watch out for flying rivet heads and shanks. Depending on your situation, you need to have the contractor put two people on the work: One busting the heads and shanks and one catching them.

 

[TomDOT]

I have seen a thousands of rivets replaced in conjunction with repainting projects, and they are typically replaced with galvanized A325 bolts. The coating system includes a zinc primer, so there are no galvanic issues. I have seen stainless hardware used (generally by the electrical folks for lighting and such) - in many areas, this causes accelerated corrosion of nearby zinc (typically galvanized poles or conduit) - I have also seen it cause accelerated corrosion of the steel. I have not seen aluminum tried, but I expect it to be a similarly bad plan from a corrosion perspective. Sure, the bolt will last, but it will accelerate corrosion around it.