Welding Tips and Tricks

how you weld 1/8 (3.0mm) or 4.0mm thick ss pipe. im gona be welding proses piping 400mm x 3.0mm to 4.0mm thick. And i think i will bewel them litle but no gap. so i can get easier trough it whit out that gap and but it on one pass at least that 1/8 thick. There gona be some xrays taken of them 10% likely and 63joints total and every joint must written down its oxygen level. I know that 3.0mm butt joint can be weld whit out eaven bewel but when tried that i need like 95-105amps to get trough it and weld pool is litle too big to controll for sure fusion. Liked to hear how you would do it Thanks.

I would be using a gap of the same diameter as your filler rod, that way you guarantee to get correctly to the root. However, this is relatively thin walled, maybe a lesser gap or no gap will be OK. There are no doubt plenty of experts who will provide further (more) valuable information.

What is your experience level?

What position is this (2G?, 5G?, 6G?)

Is this specified as a multi-pass procedure (root, fill, cap)?

Seeing this is X-Ray tested, is there a WPS you need to follow? Is so, what does it state?

Im familiar whit the procses Tig SS but thinner like 1.5mm-2,5mm And that 3.00mm 1/8 thicnes is a new thing im not sure how to do it meaning should i use gap? I just came out of my carrage and i beweled 3mm thick plate allmost knife edge and tacked the plates (no gap) 1.6mm filler and tried differend settings and best one was using laywire at 85A ading some presure on filler. Only bad thing there was hard to see that pudle "shaking" for full fusion.. In best i could feel that filler flowing easily in the budle. Theres no wps only the pipeline drawings and there are writen about x-ray tested and oxygen level chart must be writen down every joint. Im confident i can do it but want to find good technique so i dont make it harder.. And those pipes are quate small on lenght and lots of flanges and its a big 400mm radius pipe its posssible to fix inside if there is incomplete fusion ( some of them) and they are 2g and 5g positions

If it's xray I would do it in two runs. Certainly bevel 30 to 35 degrees to a knife edge and gap to your wire diameter. I would use 2.4mm. 1st pass laywire to achieve root and fill. 2nd pass would be the cap. If it was carbon steel I would use 95amps for both passes. Stainless steel maybe a little less.

Okey that gap is one choice. But but when you think that pipe is 400mm and 300mm radius and total about 63 or more joints making it one pass would be huge time saiver its about range 1.4m weld by joint and 2.8m in two passes x63... What would you think about this, knife edge 60-70° bewel no gap or only tiny 1.0mm gap. 2,4mm filler using laywire technique pushing root and cap at one pass (maybe85-100A at that range,pulsing manual on 2T) i think i could get it bretty much flush on cap and little reinforsment on root by that way? Its funny that realy my BOSS MAN should tell me and think thees things but i know that tomorrow when we start the procress he bretty much tells me to tack the pipes and start to welding... By the way we use back up gas called FORMIER.. Im not sure how it affects on Amps have used it before but nothing critical. (miss spelled that radius so its a 400mm and 300mm dimension pipe, sometimes my eng is litle lost on some words so use your imagine to understand it right, Thanks..

All methods you describe are possible. My reasoning for 2 passes is higher probability of passing xray. You have to weight up possible higher repair rate on single pass butts against 2pass butt with fewer (or none) repairs.

It's a pity you don't have a wps to work to considering xray requirement.

@Aleksi86: Please make sure you take some photos and post them. It will be interesting to see the setup.

I will for sure.. yeap litle nerves now its 10.00 at night in Finland,couple hours sleep and drive to motel and then work at there. I like this kind of stuff but im a litle too nervouse about my self Okey thanks for thoots and i will tell you later how it started...

After what I have seen from you before you have nothing to be nervous about.

Good luck tomorrow (even if I think luck has nothing to do about it )

4 mm is too thick with one pass. Specially if you have to weld in 5G position. Puddle just gets too big.

Formier is a good gas, but it should not be used with open root due to ferrite lost. Nitrogen will get in to the arc etc.

Are you sure that 2 passes are actually slower than one? Sometimes you are able to get quick well controlled passes when puddle is small. Instead of forcing the weld to punch trough the base metal with massive puddle and fighting with gravity.
Also stainless steel does have recommended maximum heat input.

Good luck buddy. Not an easy task to deal with.

THANKS EVERYONE "BUUSTING UP" My confidence I get two very shit photos my cameralins is so worse. I was told to do 3mm thick at one pass no gap.. there will be only 3mm no 4mm thick pipes.. I made some bewel and weld couople of them about 80A And realy REALY slow And let that pudle vaporize good, and i got it trough good like 80% of that pipe.but rest needet weld inside.. And that technique was hard to whach when its getting that fusion..Blaah lets see i try chainsing paramets tomorrow..

Hi so i found the technique to do it whit out gap/bewel only mismatch what comes cutting whit them on a grinder and litle smoothening thoos pipe edges on flabdisc. This ones what can be weld that bench i weld them on 10-12.clok and it worked on me 75-80Amps and dipping wire every time when that budle vaporizes and only slight movment up and back, and repeating that and moving only when that budle was very fluidy it pushed in that root at one pass..

It looks really good. Any xrays done yet?

Agreed, looks pretty good....

Thanks Thanks,they dont only look good they are good Nope no xrays yet drawings said that xrays must be taken on (is it called) out of position welds... But who the he..l knows what weld is made on where if i say so..(nothing aqainst NDT long as they dont bust my ass) just dont like them and thats it Again im learnd something new it tooked one two inch weld at one older pipe welder and i got hang of it. I ask him to show me one of the pipe how he does it and that was all i needet to fiqure it out.. So be nice to older more experienced welders eaven if they are litle crummy saved me at this time.. If i can i get better camera and shoot couple pictures at the end of this project..