root weld penetration issuies

[side-show-bob]

Hi all

I am currently doing my level 3 C&G in pipe welding and i am having a nightmare time.

Firstly
On the 2mm stainless pipe, i am struggling to get a good weld all the way round i think its due to my hand position not been right, any suggestions? Also we have been told to use filler wire by the collage so i am currently using the following set-up:

Miller Maxstar Welder (set to 30Amps)
2.4mm thoride tungston
1.6mm filler wire

When i showed my welds to the welding contractors on-site (after the laughing had stopped) they said why are you using filler wire? they dont on that size pipe. Is the norm to not use filler wire on this size pipe?


Secondly
We have to do a root weld and cap on some steel pipe, i have some 5mm pipe which i have turned a 45deg angle and left 3mm to weld through

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I have tried the following set-up :

Miller Maxstar
1.6mm Thoride tungston
1.6mm filler wire

90Amps

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100Amps

[/IMG]

110Amps

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I am getting no penetration at all any advice?

Cheers

Rob

 

[hotrodder]

Hi all

I am currently doing my level 3 C&G in pipe welding and i am having a nightmare time.

Firstly
On the 2mm stainless pipe, i am struggling to get a good weld all the way round i think its due to my hand position not been right, any suggestions? Also we have been told to use filler wire by the collage so i am currently using the following set-up:

Miller Maxstar Welder (set to 30Amps)
2.4mm thoride tungston
1.6mm filler wire

When i showed my welds to the welding contractors on-site (after the laughing had stopped) they said why are you using filler wire? they dont on that size pipe. Is the norm to not use filler wire on this size pipe?

Depends what you're doing, sometimes autogenous welds are acceptable sometimes they aren't. Need more info for the hand position thing... are we talking 6g or some other position? Can you expand on 'struggling to get a good weld all the way around' i.e. is it going wrong in one particular spot or does it keep going wrong due to, say, losing your torch angle as the weld progresses around the ?" diameter tube?

Secondly
We have to do a root weld and cap on some steel pipe, i have some 5mm pipe which i have turned a 45deg angle and left 3mm to weld through

I have tried the following set-up :

Miller Maxstar
1.6mm Thoride tungston
1.6mm filler wire


I am getting no penetration at all any advice?

Cheers

Rob

A 3mm 'land' (the bit left to weld through) is on the thick side. What about a root gap? Welders generally have their own preferences but as a generalisation you'd have no more than 1.5mm land (some like a 'blunt knife edge' i.e. bevel it to nothing and then give it a tickle with a file). Generally you'd gap it according to the diameter of the wire i.e. not thinner but some like a wider gap so it doesn't close up as much. When welding you can then see the 'land' melting and basically just keep filling the keyhole

Not having a pop but what are the instructors doing? Surely you or your company are paying them to teach you? Curious about the tungsten too... a 2.4mm @ 30A and swapping to a 1.6 @ >100A or is that a typo?

 

[side-show-bob]

Thanks for the help.

The 2.4 and 1.6 is correct they only had 2.4 at collage and I used the 1.6 at home to practice, do you think I would be better using a 2.4 for the root welds?

I can turn the land to nothing or leave a gap, I am going to try both I think as really I want as much practice as posible at all sorts of situations.

 

[hotrodder]

For the 5mm wall pipe i would use a 2.4 tungsten and wire personally. A 1.6mm would be better for the thin wall stainless but if there is none then grinding 'em with a finer (longer) taper would be the next best thing

 

[gavuk]

Agree with HR...I'd use 1.6mm on the stainless and 30amps seems low to me ,I prefer more amps and adjust travel speed to suit

 

[backpurge]

As HR says it's very much down to personal preferences, when I was doing stainless pipes I used to bevel the pipes to about 30 degrees right down to a feather edge prep and butt them right up against each other, think I used about 60a with a 1.6 tungsten and 1.6 filler and punch the root run through no probs

Are you purging the pipes?

 

[asmeix6g]

If it was me, id use 2.4 tungsten on both pipes on the stainless bout 30 degrees and butt it up tight, 1.6 wire and keyhole it at 50amps (ish)
On ya carbon one 30 degree prep again, 2mm root face and 3.2 gap. 2.4 wire and about 110 amps. Slight weave on it. Make sure the INSIDE of your butt is clean aswell! Thats very important and often overlooked!
On both pipes make sure your dipping your wire in and not laying it in. With tig the key is to make the torch do the work, walking the cup is a great way to make life easier as your spreading the heat about and also pre heating the butt infront of the torch if you like. Let us know how you get on mate
Regards