Weld Burn Through - "Rule of Thumb" 1

[NimChimpsky]

All,

Seen there are other threads on this subject but they are now closed.

A colleague of mine stands by his rule of thumb that the maximum weld leg length can not be greater than the minimum thickness of the two pieces being welded together. I can see the rule holding for thin gauge metal and sheet metal but for thicker materials I think the risk of "burn through" reduce as more material is there to absorb the heat. I understand that a lot of this is down to good welding practice and reducing the heat during welding.

Example: An I beam with flange thickness 7mm having a plate of 20mm welded to the flange with two fillet welds of leg length 10mm, plate length 200mm.

Ta

NimC

 

[Tmoose]

From outward appearances many automotive exhaust components look to have welds much larger than the pipe wall thickness.

http://f.tqn.com/y/autorepair/1/S/W/3/-/-/catalytic-pic.jpg

http://i546.photobucket.com/albums/hh435/speedkar9/IMG_6198-Copy-1.jpg

 

[Guest102023]

Find it in AWS D1.1.

Automotive exhaust systems are not subject to any structural code I am aware of.

"If you don't have time to do the job right the first time, when are you going to find time to repair it?"

 

[NimChimpsky]

Thank you for the reply.
Do you have a section of reference for AWS D1.1?

 

[Tmoose]

"Rule of thumb"

"Burn through"

"I can see the rule holding for thin gauge metal and sheet metal "

========================

The subject and post sure sounded like a "what is generally technically possible" question, not a code question, to me.

Sorry,

Dan T

 

[racookpe1978]

I "think" you are asking about maximum fillet leg sizes, right?

If so, what "good" does a longer fillet weld thickness do for normal fillet weld joints, if the maximum strength is ultimately going to be limited by the thinner of the of the two base metal pieces being joined?

Thus, if a 4x4x1/4 angle iron were being welded perpendicular to a 1 thick plate, the maximum effective weld (throat) would be 1/4 inch across - since the angle iron would tear first if an excessively larger fillet weld were used.