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RE: Bay Bridge Broken Bolts

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Bill,
Hydrogen embrittlement is an interesting field of cussing and discussing. 
The B695 is a mechanical process as opposed to a hot dipped process which 
is the A153.  The mechanical process is less durable, but it is less 
susceptable to hydrogen embrittlement.  We know more about hydrogen 
embrittlement for hot dipped galvanized material than we do for 
mechanically deposited zinc because there are more hot dipped galvanized 
steels.

Some hydrogen embrittlement is time dependent where the problem with the 
Bay Bridge bolts appears to not have required very much time.  Marine 
environments complicate the issue because a corrosion resistant material is 
 essential.

What we need is to look at other industries to see what is being done to 
combat the problem.  Corrosion resistant alloy steels can be used 
effectively.  Hilti suggests a corrosion resistant alloy steel for overhead 
 anchors in tunnels based on the studies at Mont Blanc.  The US Army Corps 
of Engineers suggests corrosion resistant alloys in some of their dam 
applications.  The Carpenter company is a supplier of high strength 
corrosion resistant alloy steels.  The post tensioned industry uses high 
strength strand but encapulates the strand in a plastic sheath.

When I worked in the telecommunications tower industry, it was known that 
the galvanized cables had a tendency for hydrogen embrittlement.  They were 
 stressed, but it was more of a time dependent issue.  During inspections, 
if there was ANY pitting, the cables were replaced.

Regards, Harold Sprague

> From: wpolhemus(--nospam--at)craworld.com
> Date: Tue, 14 May 2013 15:41:30 +0000
> Subject: RE: [SEAINT-SEAOSC] Bay Bridge Broken Bolts
> To: seaint-seaosc(--nospam--at)mail-list.com
> 
> Howard:
> 
> Again, not an expert on this...that's the basis of our occasional
> relationship over the years...but my understanding is you have the
> following:
> 
> A153 ZINC COATING (HOT-DIP) ON IRON AND STEEL HARDWARE
> B695 COATINGS OF ZINC MECHANICALLY DEPOSITED ON IRON AND STEEL
> 
> Either of which may be used to galvanize fasteners.
> 
> Is there any advantage to B695 as far as H.E. is concerned?
> 
> -----Original Message-----
> From: seaint-seaosc(--nospam--at)mail-list.com [mailto:seaint-seaosc(--nospam--at)mail-list.com] On

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