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Re: RE: Full Pen Weld at Channel

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For the last 45 years I have called for a square butt weld on both sides of the web and a 60 degree single bevel with zero gap and zero root face along with a backgouge symbol for both flanges. I know it's not a CP weld so I don't call it out as one.

 

These stringers are also called "cranked" in some areas.

 

 

Dave Lowen
jatech(--nospam--at)telus.net
Alberta 780.470.5187
California 510.550.7514

 

 

On Oct 13, 2008, spraguehope(--nospam--at)hotmail.com wrote:

This is a common issue.  This is also known as a broke back stair stringer.  Be careful so that you get what you intend.  If you truly need a full pen weld, then specify what you need.  If you get a true full pen weld, you will then have run off tabs and you will have a weld access hole through the web.  It will not be pretty.
 
Now the architect will hate that hole and point out that no other broke back stringer in existance will have a weld access hole, and he will be correct. 
 
You as the engineer have a dillema.  Swimming upstream in the world of convention or engineering something that will satisfy most everyone. 
 
I have had this conversation with a lot of welding and fabricating gurus and resoved to the following:
Show a PJP weld symbol with E in the spot indicating the effective weld thickness.  In the tail of the weld symbol indicate:

PJP  E=MTL THICKNESS - 1/8"
WELD ACCESS HOLE NOT REQUIRED
NDT NOT REQUIRED
VISUAL INSPECTION REQUIRED
 
Show the same weld symbol for the web weld.  Calculate if this is sufficient for the weld you need. 

You can have it ground flush if required. 
 
The above weld will have a prepared beveled surface.  It will be close to a CJP, but not quite.  It will look like all of the other welds out there on stair stringers, but you will have some idea of what you have.  The vast majority of these welds existing in the field are just butt welds that are not prequalified and you have no idea of the thickness of the effective weld. 
 
Go to any project where there is a broke back stringer and you will not find a weld access hole even if the weld was specified as a CJP.  It makes you wonder what weld was provided.  At least with the notes that I now use, I am getting a definable weld and it is inspected. 

Regards,
Harold Sprague




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