"Burn Through" Definition 2

[vanci]

Hello Everyone,

Does ASTM, AWS, or ASME have an official definition of "Burn Through"? I could not find anything in ASME, however I am new to the code in its entirety. I do not have access to the ASTM or AWS specs.

Thank you in advance.

 

[metengr]

Look at ASME B31.3, internal intrusion of the weld root. See Table 341.3.2 for an explanation on limits.

 

[gtaw]

Burn through produces a hole through the root face, the pipe wall, or thickness of the base metal. Imagine trying to weld thin base metal with the current set too high. Usually it is associated with excessive heat input when depositing the root bead or the second layer (hot pass).

It isn't the same as melt through, which is weld metal protruding past the root when depositing a weld from one side of the joint. Melt through is often associated with single sided groove welds.

The difference between melt through and burn through is melt through is not necessarily a bad thing. It simply means complete joint penetration has been achieved. Burn through on the other hand results in hole through the joint that usually has to be repaired to keep the joint fluid tight.

ASME B31.3 limits melt through, but refers to the condition as internal protrusion.

Best regards - Al

 

[vanci]

Thanks for the help guys. As you know in the welding field, this is a widely used term and most people would agree to its general meaning. However, I have "no burn through" called out on a drwaing and am afraid this could be open to interpertation when the weld is inspected. I think I have the creator convinced to change the wording on the drawing but in doing so, I also started the hunt for an actual definition of burn though in some type of nationally acceptaed standard.

Thanks again.

 

[gtaw]

You may consider AWS A3.0 Standard Welding Terms and Definitions.

Burn-through has been considered to be a nonstandard term for excessive melt-through since 1994 and possibly before that.

The term "excessive melt-through" does not convey the difference between excessive metal on the root surface side of the weld (internal protrusion) and a physical hole through the base metal in the root of the joint (burn-through). In my mind and to many welders that have to contend with the problem, there is a big difference when they have to fix the two different defects.

Excessive melt-through will not result in fluid squirting out of the vessel or pipe. Burn-through, if left as is will result in fluid escaping from the vessel or the piping. The latter could be a serious problem in many cases.

“Hey, A2 Committee! What’s sa matter with you?”


Best regards - Al

 

[stanweld]

From API 1104, 9.3.7.1, "A burn-through (BT) is defined as a portion of the root bead where excessive penetration has caused the weld puddle to be blown into the pipe."