IF in XRAY

By Lawrence (*****)

Date 08-23-2010 11:00

Issufficient fusion where?   At the root? at the toes? on beveled edges?

Open root? Fillet?

Pipe?   Plate?

225 amps is pretty high for short circuit parameters.. almost spray/globular kind of current.

Could be gun angle too..   or travel speed///

Give us more data and the solution will become apparent.

Gas issues would produce porosity rather than lack of fusion most likely...

By MBSims

Date 08-23-2010 11:33

Incomplete fusion with GMAW short-circuiting mode? Hmmmm...I wonder what could cause that?

It's a technique problem. Always keep the wire on the leading edge of the puddle, or this is what you get with GMAW-S. Also, don't forget your not supposed to be using RT for welder quals with GMAW-S.

By PipeIt

Date 08-23-2010 12:12

Open root yes on pipe

CWI'S are noting that a high CFH would/could cause a venturi effect on puddle pulling in impurities I do agree that would show up as porosity rather than IF.

to address MBSims on RT for test it is also a bend test tensiles have been fine busting on 0ne of four strips on face and root bend. so to help us out they have been shooting strips using another type RT method less a source to see what the cause could be.

The DE Qualifies the shop and the RT with a source qualifies the welders under the B31.3 Section IX, take note this is not my strong suit. They have shot good with a source when they shoot the strips with out a source is where we see the IF.

By MBSims

Date 08-23-2010 21:45

Glad to hear the welders are being qualified using bend tests. Sounds like the RT is informational only, so it should not be the basis for passing the qualification test. By "RT with a source" are you referring to gamma ray vs. x-ray? I'm not sure what you are referring to here. Below is what ASME IX says about using RT as an alternate to mechanical testing. You can see that RT is not permitted for GMAW short circuiting mode, regardless of the RT technique.

"QW-304 Welders
Except for the special requirements of QW-380, each
welder who welds under the rules of the Code shall have
passed the mechanical and visual examinations prescribed
in QW-302.1 and QW-302.4 respectively. Alternatively,
welders making a groove weld using SMAW, SAW,
GTAW, PAW, and GMAW (except short-circuiting
mode) or a combination of these processes, may be qualified
by radiographic examination, except for P-No. 21
through P-No. 25, P-No. 51 through P-No. 53, and P-No.
61 through P-No. 62 metals. Welders making groove
welds in P-No. 21 through P-No. 25 and P-No. 51 through
P-No. 53 metals with the GTAW process may also be
qualified by radiographic examination. The radiographic
examination shall be in accordance with QW-302.2."

By PipeIt

Date 08-25-2010 11:45

MB Yes I am referring to gamma ray vs. x-ray. You are correct the RT is informational only.

"You can see that RT is not permitted for GMAW short circuiting mode, regardless of the RT technique." Interesting! Need to look into this.

Thanks,

PI

By PipeIt

Date 08-23-2010 12:26

Just above toes is where it seems to be the problem I didn't address that in my last response. Roots? those look fine according to the CWI's.

By 803056

Date 08-23-2010 14:15 Edited 08-23-2010 14:17

Who is reading the film? CWIs, by virtue of having their CWI credentials, are not qualified to interpret radiographic film.

Not that I am surprised to hear they are experiencing incomplete fusion, especially if they are using downhill progression.

Al

By TimGary (****)

Date 08-23-2010 14:37

While GMAW-SC may theoretically work for what you're doing, keep in mind that it is a process intended for the joining of light gage sheet metal, and is infamous for it's poor penetration, LOF issues. It may be OK to use for full pen pipe welding, but only for drain or very low pressure lines.
If you need to develop the full strength of the base metals you're welding together, you need to use a process that lends itself for that. For example, if you change to Pulse transfer, you could retain your fast wire fed GMAW equipment and deposition rates while increasing the amount of ultimate penetration, thus decreasing the potential for LOF defects, and broken coupons during bend testing. Other methods would be to use flux cored or metal cored wires. This would allow you to get up into higher penetrating spray transfer modes, while still being able to weld in position.
You really need to consult with the project engineer about the design strengths that these welds are to be subjected to, and determine the best welding methods from there.

Tim

By Johnny Walker (***)