Welding Tips and Tricks

Hi folks, new to the forum. I've been working my way through Jody's vids on youtube and have picked up a ton of hints and tips. I have a repair on the part below and I'm looking for some ideas on the best way to go about it. It is made of 316SS, the material that is worn off amounts to about 0.040"undersize on the OD. The wall thickness is 1/8" and I need to keep the ID as true as possible. The machinist will be spinning off what I build up on the outside. My first thought was to tig it at a really low heat. I’ve numbered a couple ways to run the beads, but I’m not sure which would be best. I can also mig if that might be better? Machines I can use for this are a Miller Syncrowave 250DX Tig(no pluse), Miller 211 Mig, Miller 252 Mig, and a Miller Maxstar 150 STL Tig. Any help on recommendations is greatly appreciated!

MillwrightWelder,
Here is a video from Jody with a similar repair....http://www.youtube.com/watch?feature=pl ... TqvEXS3f88
I personally would TIG weld it keeping it as cool as possible, following the curve of the pipe. As far as keeping it true, that pipe may not be true already, so any warping that might come from welding should easily be taken out when/if the other end gets welded.Just my two cents, there are many ways to skin this cat.
-Jonathan

Not my field of expertise, but might it be more practical to move the flange to a new piece of pipe?

Cheers,
Richard

I think Tig will give the lowest heat input - but the amount stainless moves when welded it's unlikely on that wall thickness that it will stay round - obvious answer is try to find a large piece of round that will go inside ( aluminum or copper being the best ) to act as a heat sink & only weld in short runs alternating from side to side so hopefully stresses are evened out - if the part needs to remain the same material then weld it - but assuming that is some sort of drive flange that a bearing has spun on rather than food grade pipe it may be more practical & have less heat input to Tig braze the build up area - SIF make a nickel / brass alloy that takes well to stainless & machines very well - sure others will have alternate opinions.

Hey,

This may be beyond your reach, but you can get a process performed call metal brushing.

http://www.metalsurgery.com/brush_plating/

This would be good for a part that can stand very little distortion.

Mick

I would make a round copper back up with gas purge, weld in one inch sections and plan on welding the id depending on the tolerance you have to hold.

That would actually be an ideal job for metal spraying if you know anyone with the equipment .

noddybrian wrote:That would actually be an ideal job for metal spraying if you know anyone with the equipment .

Spraying with plasma would be ideal, but since welding was mentioned I figured its not an option. If you could find someone to do it, it would be costly on a one part run basis.

Just buy a new chunk of SS and have the machinist make a new part from scratch.

If I were quoting that job I would give the machinist 8 hours to make it from scratch.

I have built up lots of parts with weld, some times it was the wrong choice.

Good luck.

I think machining the flange off and welding it to a new pipe would be the fastest option.

So I finally got around to building up these parts. Thanks to all that replied! I decided to tig them and built a plate/gasket for the bottom so I could fill them with water to keep distortion to a minimum. I welded with a 1/16" tungsten and 1/16" 316SS filler. I welded a little bit at a time and changed the water often. On the second one I tossed a piece of aluminum flat bar in to see if it would help strip away even more heat. The machinist was happy with the results. The beads on the outside showed little to no discoloration and the inside showed a little bit but no sugar or bumps. I shakey freehanded using the dip method so I wont mind the machinist turning off my messy beads! Anyway thanks for looking!

Looks good! This liquid backing idea was ingenious and appears to be pretty effective. Is it common to do this in industry?

-- Pete

I can't take full credit for the idea, I remember seeing a pic on the net of a guy welding a shaft and the end of it was in a bucket of water. I figured I'd put my own spin on it. Ideally if I could have had a constant flow of water going through it would have been even better. I could really tell when the water was heating up as the puddle would get way more fluid, at one point I had the water boiling! I could have make a cup of Joe.