Welding Tips and Tricks

hello there,
Im in process of doing my 5G pipe weld on mild steel test,

the pipe is 80mm O.D bevelled at 30'degrees
Prep: knife edge root face, 1.6mm root gap

root: 170-175amps using laywire tech, on a 2.4mm filler rod,
im getting peno but its not beading its always flat, how can i fix this
?

my filler/hot pass is effecting me big time, i can get any technique, its all over the place and i keep washing out the bevel, can some one help me with this problem, amps, filler rod, techniues ?

im from Australia so sorry about the metric measurements,
regards daniel

Wow!

If you're running 170+ Amps on a knife-edge root, you must be hauling ass!

I suspect you need a cooler root, either by adding land or reducing amperage. What does the specification for the test weld allow?

Steve S

No undercut, 1mm suk back on peno, 2mm reinforcement

australinwelder wrote:No undercut, 1mm suk back on peno, 2mm reinforcement

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Australinwelder.

If you had adequate penetration during from the root pass, you might be accidentally causing the suck-back during the second pass by running too high on the heat.

This technique is intentionally used during the second pass, by some, to bring isolated locations of excessive penetration back within acceptance criteria.

Alexa

Alexa, I think Daniel was giving the pass/fail points for the acceptence of the weld.

In his original description, he describes his root as "flat", which is a pass by these criteria. I think he's looking for some internal reinforcement, a positive internal bead as opposed to "flat" or sucked-back.

@ Daniel, I was asking if the weld test has a WPS (Weld Procedure Specification), describing allowable amp ranges for each pass, fit specifications like bevel, land, and gap, tungsten sizes permitted, filler rod sizes permitted for each pass, etc.

If suck-back of 1mm is permitted, though, it sounds a bit like a "however you can get it done quickest" test.

Steve S

australinwelder wrote:No undercut, 1mm suk back on peno, 2mm reinforcement

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Otto.

Rereading Australinwelder's last post ... yes ... it does seem like those are part of the acceptance criteria.

This brings to mind, that at times a weld can be saved from repair or cut out, if the isolated area of suck-back is less in depth, than the cover pass reinforcement. So for example, if there is an inch length of 2 mm deep suck-back, then if the cover pass in the same one inch length location, is 2mm or over, then it might be interpreted as acceptable. The logic is that the minimal throat (through section thickness) of the weld is at least equal to the thickness of the base metal.

Tanks for the explanation.
Alexa