A490 (I believe 325 as well) bolts are already readily available as Type III, which is weathering steel which is inherently corrosion resistant.
ASTM also specifies a couple of different coatings already - I know Geomet and Magni 565 are included, I think there's one or two more.
So ultimately anyone hot-dipping A490 bolts is either inexperienced, stupid, or determined to shave pennies at the cost of installed reliability (which obviously is a huge problem).
Ok engineers (retards?), let's team up and invent a "sex drive" screw that no other engineer will be able to resist in specification. Million dollar opportunity here. I apologize in advance for reducing the quality of this thread and hope we get a laugh but don't steer the discussion.
It states that the anchor rods in question were galvanized without being acid washed (or pickled) prior to dipping, instead they were blast cleaned to avoid the hydrogen embrittlement issue. The conclusion given is that the hydrogen embrittlement was caused by the 5 year exposure to salt water (during construction). The claim is that the galvanized coating was damaged at the thread-nut interface (peened the threads) to prevent turning, and this (and any other damaged areas to galvanizing) is where the corrosion happened over the 5 years which caused the hydrogen embrittlement. This of course is presented by the AGA - so it is in their best interest to remove all blame from the galvanizing process.
SwinnyGG, Type 3 (weathering steel) bolts are great in the correct environment. Coastal areas are not one of those environments.
I have seen a number of occasions where bolts or other parts with high hardness failed due to hydrogen embrittlement in services where no hydrogen was known to be present. In all of these cases, the finding was that sulfide or chloride corrosion had produced hydrogen as a byproduct which resulted in the embrittlement.
I think you have to go out of your way to make A325 susceptable to hydrogen embrittlement... not so the A490. Weathering steel is not a panacea... it rusts and can produce an ugly stain... also on the concrete surface below... also in aggressive environments weathering steel can 'corrode' faster than plain steel because the 'tight' oxide layer produced is removed and reforms quickly.
Rather than think climate change and the corona virus as science, think of it as the wrath of God. Feel any better?
Dauwerda, thank you, that is a much more recent release than anything I have seen. JJ, the bay is salt water so your explanation makes sense. Something to think about, many of the bolts that failed required grouting. Polysulfide is commonly used in sealants. Perhaps that was a contributing factor as well.
In January 2016, an ironworker got hit in the face with part of a bolt that snapped when he was trying to use a torque wrench to tighten it, with the piece of metal ricocheting off an overhang and splitting his lip open when he looked up.
"When you look at them, bro, the heads of them were like hollow, bad spot, sometimes the shank-lead to the thread has got a hollow spot," one of the ironworkers told James McNall, the project's safety director at the Port of Coeymans, the Times Union reported.
A confidential report from the Thruway Authority put the likelihood of bolts failing at 1%, but also listed a snapping rate as high as 50% as a "worst-case scenario," the Times Union said.
