cs pipe poor fusion

Date 07-17-2007 09:15

Poor fusion of the mig pass to the tig pass?? or poor fusion of the root pass (tig pass)??
Are you running hard wire down hill? I assume you have a full penetration tig pass? Really need more information I think.

By js55

Date 07-17-2007 13:34

Where on the pipe are you welding? Rollouts or position work? Short circuit or spray(with 75/25 I'm assuming short circuit)? Why?
What thickness of pipe? SC is generally not recommended for thicness exceeding aoubt 1/4" or 3/8" due to heat sink. And if your carrying too much metal it will cold lap on you.

By jarsanb (***)

Date 07-17-2007 15:35

I also am assuming that you are running solid wire downhill. And I will assume that your lack of fusion is between your passes near the bevel faces. You didn't mention what material thickness you are welding, which would affect the parameter selection, but by the sounds of it your parameters are too low or you are trying to carry to large a weld puddle. Qualification tests that I administer here at this company consist of GMAW-S (Short Arc) on pipe downhill. One of the tests I give is this process is on .814 thick, 6" diameter pipe, no preheat, fixed 5G, 100% CO2. GMAW all passes. I perform side bend tests on these specimens obviously. The seasoned welders have absolutely no problems with inter-pass Incomplete fusion. The new guys coming in (usually with a SMAW background) do have rashes of problems. Most seem to be the product of trying to carry too large a weld puddle downhill, which really should not exceed 1/8" thickness in a single deposit or they just don't add enough voltage to wet the toes out properly. The procedure allows for weaves or stringers - most weave to a width of about 5/8" per pass on fills and cap and overlap them. If you could give some more info it would be beneficial

By 1tigger59 Date 07-18-2007 02:47 Edited 07-18-2007 03:01

poor fusion of the mig pass to the tig pass we are running hard wire .035 75/25 on the gas runing 3o'clock to 1 on rollers running uphill weaving stringers. have full penetration on tig pass nice looking root the companys procedure calls for globular pipe is 8in sch 160

By Lawrence (*****)

Date 07-18-2007 03:51

Rotated Sch 160 should be running spray transfer near the top rather than globular at 3 O'clock.

By ssbn727 (*****)

Date 07-18-2007 05:00

I agree with Larry :)

Respectfully,
Henry

By jarsanb (***)

Date 07-18-2007 15:01

Definately. Good suggestion. Maybe a small change in sheilding could solve the problem within the procedure. However, there is a qualified procedure for this process that the welder needs to follow, so it sounds. Not sure what the technique is that you are using to deposit the first fill pass nor where the parameters actually are within the globular range specified in the WPS, which could be an issue. But I have seen simular issues if the welder tries to put in a quick weave on that first GMAW pass over the root if the included angle is around 60 degrees (fairly tight in there). That pass doesn't need any side to side manipulation. If this isn't the case at all, I would look at the electrode extension. This pretty thick, it would be very easy to draw a long stick-out, over 1 inch. With the .035 wire/globular I would try to keep it just under 3/4 inch. Good luck to you.

By jarsanb (***)

Date 07-18-2007 15:14

I mention the electrode extension because some like to use a large nozzle diameter when using spray/globular. The set-up with the tip and cone can be recessed up to 1/4". If the nozzle is large, around an inch, it is possible to press the nozzle against the bevels and still not be able to produce the desired extension due to the tip being recessed.

By 1tigger59 Date 07-19-2007 02:14

This weld test is for the company that I work for . It is all suppose to be done per wps tip is little less than a 1/4in. was weaving the first mig pass to keep from burning through.