Fillet Weld Question

Date 03-19-2009 19:33

Weldcome to the Forum:

Try 5.22.1 Fillet Weld Assembly

"The parts to be joined shall be brought into as close contact as practicable. The root opening shall not exceed 3/16 except in cases involving shapes or plates 3 inches or greater in thickness." etc. etc.

By hogan

Date 03-19-2009 19:51

In addition to what bryon has stated, try not to think of a "T" fillet as having a root. As you have stated you can put two pieces together to form a "T" and then fillet weld them together. While this connection has a root, don't think of it as you would a CJP. Think of it more as just naming the location of the first pass(root pass). It is the intent of the code that these two pieces should be in intimate contact. The section that byron has listed allows for some tolerance for this. You may not always be able to bring the two plies into intimate contact. So the code allows you to have a 3/16" gap for material under 3", but it also requires that if your gap is over 1/16" you shall add the size of the gap to the size of the fillet. There is also no requirement for the base-metal to be prepped (beveled like a groove weld). Hope that helps.

By CHGuilford (****)

Date 03-20-2009 13:16

Instead of calling it the "root" I like to call it the "bottom of the joint". Even though the term root is correct, people seem to get hung up on it.

By DaveBoyer (*****)

Date 03-20-2009 02:45

I don't know how this is viewed by D1.1, but for reasons of distortion controll sometimes it is advisable to provide a small gap between the parts. 1/16 diameter soft iron wire can be used where this is the case. This can be done to prevent having a fully restrained joint as well.

By Fredspoppy (**)

Date 03-20-2009 16:34

While it is not "normal practice" to use a gap (either plain standoff or use of some ductile spacer) on heavy duty, structural "T" joints, it is the "recommended practice" when welding on socket type joints. Either a Gap-A-Let (TM) or the practice of full insertion, scribing a distance for stand-off (often 1/16") and backing out are commen methods for avoiding high levels of restraint and potential centerline cracking of the fillet weld.