Reinforcement Weld Measurements

[APiccolo]

Good Day,

I am a Quality Assurance Coordinator at a large manufacturing plant. We've had problems with our submerged arc welding on a new piece of machinery we purchased. I've been pulled into the project to assist with requalifying our process to ensure that we can continue welding it without problems (we we're experiencing cracks on the ends of long seam welds. I'm being tasked with locating a way to measure the height of our reinforcements accurately so we can efficently analyze how well we are doing without over reinforcing. I know there is measurign devices out there but I haven't found one to suit our needs yet. Given that our long seams are on a large pipe in essence it is not on a round surface. And also given that the top of the reinforcements are round as well it really leaves it at the mercy of human error to measure what the highest point is from the round surface on either side of it.

Any help would be greatly appreciated. I am not a welder in the least and if I reread what I just typed to myself I probably wouldn't understand it again.

[David R]

I didn't get it either, got a picture?

David

[Burnit]

If you could provide a diagram or drawing even a rough sketch that would be a big help. I know that might be proprietary info you cant divuldge.

We had (I think) a similar problem using sub-arc to weld together large beams about 60' long.

I am unclear though about what exactly your are trying to measure. the size of the weld itself?

[enlpck]

See: http://www.mcmaster.com/ctlg/DisplCtlgPage.aspx?ReqTyp=CATALOG&CtlgPgNbr=3288&term=Welding%2bGauges&ScreenWidth=1280&McMMainWidth=957&sesnextrep=136577408468948
(near the middle) for an example of a weld inspection gauge. The 'multicheck' gauge is probably the most generally useful. The pipe alignment gauge may also be of use.

The weld is longitudinal on pipe, no? A custom adapter for the pipe, based on pipe size, will allow reinforcement measurement directly and easily. The adapter should fit the OD of the pipe away from the weld area, and have a top that is level with the tangent plane to the pipe surface. (see pic below)

A three-point gauge will also do the job, though it requires doing some arithmetic. (three-point gauge is similar to a lens gauge, http://www.medrounds.org/optics-review/2006/05/39.html and can be used to find outside diameter of a cylinder. Mine is made from a standard dial indicator. Use is based on simple geometry: http://mathforum.org/library/drmath/view/55037.html)

[Donald Branscom]

I think the awnswer is simple.
It is submerged arc done with an automated welding positioner right?
I would bet that it was not tacked first and was welded starting at one end and a continous weld all one direction, One pass. Right?

The WPS needs to be changed. Like maybe a initial pass for tacking ,then a final pass for finish welding.
You said you were getting CRACKS but you did not say where. Was it the base metal or the weld itself that cracked? Or was it in the HAZ?
If the weld itself cracked it can be caused by gaps that are too wide. OR it can be a problem with the elongation rate of the filler material. They should look into filler material and base metal compatability.

Travel speed too high?

[Engloid]

Cracks at the crater are pretty common. It can be caused by the rapid cooling after the arc stops. What you may want to do:

1) Specifiy the weld to be performed as it currently is.
2) Grind the crater until cracks are gone.
3) Use dye penetrant to detect any cracks that may still be present. If they are, grind deeper.
4) After it passes the penetrant test, use TIG to fill back up to the full cross section of the weld.

[William McCormick Jr]

Good Day,

I am a Quality Assurance Coordinator at a large manufacturing plant. We've had problems with our submerged arc welding on a new piece of machinery we purchased. I've been pulled into the project to assist with requalifying our process to ensure that we can continue welding it without problems (we we're experiencing cracks on the ends of long seam welds. I'm being tasked with locating a way to measure the height of our reinforcements accurately so we can efficently analyze how well we are doing without over reinforcing. I know there is measurign devices out there but I haven't found one to suit our needs yet. Given that our long seams are on a large pipe in essence it is not on a round surface. And also given that the top of the reinforcements are round as well it really leaves it at the mercy of human error to measure what the highest point is from the round surface on either side of it.

Any help would be greatly appreciated. I am not a welder in the least and if I reread what I just typed to myself I probably wouldn't understand it again.

Do you use disposable starting tabs or something similar?

The picture in the attachment does not depict your exact task. However the principle is the same. You could also use a piece that is even with the surface of your pipe. And then just remove that piece.

It is probably the lack of preheating that is causing the problem, on start and or on finish.

This process was successful.


Sincerely,


William McCormick

[Brainfarth]

We had some problems with cracking on the ends as well. The answer was to use longer run-off tabs and to cut them off all the way rather than cut part way and beat them off. As far as I know, this answered the problem.