Friday, December 2, 2011

RE: STEEL: What would you do?

For some applications, I like to use knee joints. 
If my understanding is correct I would avoid a 45 degree mitered welded connection at the corner, you would have difficulty in the fitting, prep, and welded joint.  My choice of welds for HSS are (in order): fillet, flare bevel, prequalified CJP, and prequalified PJP last because of the problems of a backer bar.   You can also insert a stiffener plate into the HSS to reinforce the walls, if you would require a stiffener. 
Now if you are going to have an ASME welder (piper), that is a different story.  For ASME BPV welds, I like the CJP qualified welds.  But those welders are on another level. 
Any way you cut it, you are better off doing as much in the shop as possible. 

Regards, Harold Sprague

Date: Fri, 2 Dec 2011 12:20:50 -0500
Subject: STEEL: What would you do?

I've got to draw up a waler system for a sheet-pile vault. The client's typical practice has been to use HSS members for the walers (including struts, bracing, etc.)
The outside dimensions would be about 30 ft x 35 ft. I would rather make the "knee joints" at the four corners as mitered welded connections for strength, but that wouldn't lend itself to welding in place. OTOH, I COULD have the whole thing shop-fabbed and shipped out fully (or partly?) assembled.
I just don't have a feel for ALL the pros and cons here, or if it is even doable with a frame that big.
Any opinions?