[TowerTalk] A near imminent TX-455 failure (Bob Shauger)

[TexasRF@aol.com]

Hal, if possible, please give us a few words about hydrogen embrittlement.  
To me, this is a new concept and would like to know more.
 
73,
Gerald/K5GW
 
In a message dated 11/14/2005 10:15:45 A.M. Central Standard Time,  
halken at comcast.net writes:


I  guess I have a different take - looking at the pictures and having
reviewed  these sorts of failures for years in the aerospace industry.

The legs  (not the welds) have broken at the point where the side plates
are welded  to the legs.  Also, the failures show no sign of ductile
deformation -  note how sharp the cracks are.  Also, the failures have
occurred at  the point of maximum applied tensile stress to the leg
members.  

This looks like a classic hydrogen embrittlement failure of the  legs.

http://www.corrosion-doctors.org/Forms/embrittlement.htm

A  few thoughts:

- The third leg will likely fail the same way, at any  time.
- This is fixable - the legs need to be realigned and backing  stock
welded in place by a professional.  All three legs!  
-  The rest of the tower is suspect, but the failures have occurred at
the  point of maximum applied tensile stress - as you move up the tower
the  loads get smaller and the chances of a hydrogen embrittlement
failure go  down.  The rest of the tower may be okay.  It should be
THROUGHLY  inspected - every leg and tubing weld as a bare minimum.
- It is difficult  to detect cracks with the eye and impossible to detect
hydrogen  embrittlement without very sophisticated equipment.  Applying
some  side force with a pry bar may be the best you can do
inspection-wise.
-  It is quite possible the manufacturer has seen this before.  Get  them
to talk to you - if they will.

Good luck -  
Hal
N4GG


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