BTC-P4 (modified?)

Date 01-23-2006 19:41

We are trying to stay with all prequalified joints, but this came up in discussions here at work:

We have a 3/8" thick shear tab that is square cut and laying at a 45* angle to the web. The design drawing calls for a BTC-P4 in the 45* groove(made by laying the plate over 45*) and adding a fillet weld to the other side. Problem is the land is zero and a prequalified BTC-P4 calls for a 1/8" land min. I guess I can use my -1/16" in the fitup so I'm half way there. (we are using FCAW and SMAW processes)

Can I get away with not furnishing the land and still be considered prequalified?

I feel we get a better joint by not having the land, but was looking for other opinions on this from the forum. I'm not sure why this question hasn't raised it's head in our shop before now, but anyway here it is.
John Wright

By QCCWI

Date 01-23-2006 20:18

Theoretically without the 1/8" landing you will have a full pen weld which should be better than a partial pen weld.My personal opinion is the weld should still be prequalified.

The bigger problem I see is the BTC-P4 joint designation.The way I read what you wrote is:The plate gets welded on both sides. If the plate gets welded on both sides it cannot be designated BTC-P4 because Note 2 in the notes for Figure 3.3 and 3.4 (page 72 in the 2002 AWS D1.1) states the "Joint shall be welded from one side only."

That being said I have complained about the use of the BTC-P4 and alot of the other one sided welds being drawn to show weld on both sides before.All I did was educate a detailer for about 20 seconds or just long enough for me to hang up the phone whichever is shorter.

By jwright650 (*****)

Date 01-23-2006 21:07

We could just make it a CJP and forget it, but then I need to UT all of these if we call out a CJP designation. I'm trying to get the correct symbol for what the design drawing calls for without creating alot of extra work by qualifying a procedure or addition prep to the materials. We just want to put the shear tab up there at a 45* and weld'er up.
John Wright

By swnorris (****)

Date 01-23-2006 21:39

John,

We always just, as you say "put the shear tab up there at a 45* and weld'er up". As you know, the shear tabs must be welded from both sides. Note 10 on page 73 states that the orientation of the two members in the joints may vary from 45 to 90 degrees for T joints. The engineer will most likely let you just weld them up. Why not just sketch up something and fax or email to the engineer? We've never had a problem getting approval to just "weld em up".

By QCCWI

Date 01-23-2006 21:40

You could make it a BTC-P5 which gets welded on both sides. Still would have the landing problem but once it is welded I cannot look at it and tell how much landing was there before it was welded.Truthfully I do not see where the landing would really hurt in on a joint designated to be welded on both sides.