[waynebergman]

First project coming up with stainless tubing. I understand the tubing should be brushed with a stainless steel brush before and after welding but I am wondering about the clean up of rough edges before that. Is it ok to sand with a 120 flap disc, clean with acetone and then clean with SS brush. I know aluminum does not like the 120 grit sand paper first so was not sure about stainless?
Thanks Wayne

[gurew]

well first and foremost. is this new or old metal...i can help you TONS if its clean new metal

[waynebergman]

Yes it is all new stainless steel. A freind has bought some exhaust parts for his car.Making an all new system right from motor to tail pipe. All stainless tubing except a few areas will have stainless tubing to regular steel collars. I know the stainless tubing is not magnetic but not sure what type of stainless it is. Right now I have some ER316L 1.4 rod that I will try. Its the only rod my local store in my area has. I may have to make a trip into the city to see about the best rod to use. I will try what I have got for now.
Most of the tubing fitts inside the piece it will be welded to so mostly lap joints with a few but joints here and there.
My plan is to clean rough edges with 120 flap disc,stainless steel brush, and aceatone clean. Not sure on amps but will experiment as I go. My unit only pulses max at 20 so I will set pps at 20,pulse amps at about 30 percent and time at about 30% as recomended I think on this site for stainless pulse settings to start with.

I am more used to welding 1/8th wall aluminum so I guess my main concerns is preping the stainless steel properly and dealing with the thin 1/16" wall thickness, also I am wondering if on the butt joints with the tubing only being 1/16" would I still bevel my edges?

I am a newbe for sure so any help is welcomed. l

Thanks wayne

[jpence38]

Wow, you guys make it sound like brain surgery. Really no need to go through all that for new stainless pipe. Oh, use some 409 rod if you can find it. That's what is usually used on stainless exhaust which is probably a 410.

[gurew]

erm... use the 316 rod you have, thats perfectly fine. ideally you would want to use 309 if welding stainless to mild steel but 316 also works well as an all around filler for SS

prepping..no bevel on stuff that thin, just wipe it down with denatured alcohol or acetone and away you go remember ss is low amps...so use 3/32 tungsten, 1/16 or smaller rod, start low amps around 45 and work your way up....

if you want lots of color use the biggest gas lens you can get, set the gas accordingly, and do 5-6 small beads then stop...repeat...should yield lots of blue/purple/gold/white beads

[waynebergman]

Thanks Gurew.....will do! I don't have a gas lens so I will be using a #5 cup. Come to think of it I have 3 sizes 5,6 &7 but I have only used the #5. My unit shows litres per minute and I usually go about 8. Does this sound like an ok combo #5 cup and 8 lpm?

thanks wayne

[gurew]

should be fine. you just wont get the beautiful colors thats all. just go slow and take your time. dont do long strings of beads...onlye 4-5 dots/beads at a time, stop and let it cool while holding the torch over the weld area to cool it


stainless will overheat very quickly, this is why you only do a few beads at a time...


also do you plan to back-purge, how do you plan to shield the back of the weld ?? solar flux would work great for you if i understand what you are doing correctly....but you have to shield the back of the weld for sure else it will be very brittle and prone to break...esp under heat

[waynebergman]

Thanks Gurew.............not sure on purging the back side or the wipe on treatment. I will continue to look into that part of the puzzle as I practise on off cutts...........wayne