Weld prep routine

[OutbackL130]

How do you prep fresh new metal from the steel mill before welding?

 

[k0ua]

How do you prep fresh new metal from the steel mill before welding?

I usually hit it a bit with a wire wheel. And if that does not look shiny enough for me, I use a flap wheel on the 4 1/2 inch grinder

James K0UA

 

[Furu]

I am far from being an expert.

I wire wheel it for SMAW and O/A.
I wire wheel followed by 4.5 inch abrasive grinder pad for TIG.

 

[k0ua]

I am far from being an expert.

I wire wheel it for SMAW and O/A.
I wire wheel followed by 4.5 inch abrasive grinder pad for TIG.

Yes definitely the bare shiny surface fior TIG.. but the duller surface is fine for SMAW. I guess he didn't really say what process did he?

 

[Thomas]

I just buff to shiny.. remove dirt rust etc.

 

[Shield Arc]

Well all you get in construction is a quick wipe off with your glove! If the mud is still to thick to get an arc going, wipe it again.

 

[Pit Man]

Yep , grind off the mill scale with a flapper disc or wire wheel. Then wipe down with a quick drying solvent like acetone , paint thinner . This is for ASME code welding.

 

[Baby Grand]

With 6010 rod I rap it with a hammer to knock the loose rust off and then commence to weld it.

 

[woodlandfarms]

Well to the pro welders, I mean those who do / did it for a living (shield arc) are you being serious that for stick at construction sites you really don't clean the metal beyond just being clean (knocking the scale off, rust off). I know for Mig and Tig clean is necessary (I assume for current flow) but stick seems to be the "just as long as you can touch metal you will be fine".

 

[Shield Arc]

Only for code welds! But not all the time! When we built the West Seattle bridge in the early 1980s I was splicing 24-inch pipe pile right on East Marginal way, 100% X-ray. It was pouring down rain, water was running down the inside of the pipe and out the joint. The welding inspector was watching me weld. I'd make a pass, and have to grind out two because of all the pins holes. I was standing knee deep in water inside a cofferdam. I asked the foreman to send someone up and put a cover over the pipe to stop the water. He replied "I thought you said you could weld"! I went back down in the cofferdam to continue welding, the inspector said to me I think I'm going to shut you down. I said good idea, but they can get some one else to make these welds, I'm out of here!

 

[OutbackL130]

Lol shield arc that must be so true to how it is for welders in the real world.

In the perfect world for mig welding should you always completely grind off the mill scale and wipe down every square inch with heavy degrease solvents?
Honestly I dont have time or the patients to clean 100's of joints this way. When I tell people how I do very little clean up on mild steel before mig welding they look at me like I came from another planet. The parts I make are more ornamental per say, non structurally critical and not subject to code inspection.
With that said I'm interested to know how others clean or dont clean steel for mig welding.

 

[Arc weld]

That inspector should have lost his license! New steel usually doesn't require any cleaning. For TIG and pipe welding it has to be real clean but most structural and general welding is done without any cleaning unless it is caked with mud or dirt. Minor rust or mill scale isn't a problem. S6 MIG wire has helped in this regard because it has more deoxidizers than the old standard S3 wire.

 

[john40981]

I am just a backyard welder but been doing it for 35 years with arc, mig and tig and I only clean back the mill scale for tig, don't clean much at all for the others and welds are always good for my purpose.

 

[Shield Arc]

Lol shield arc that must be so true to how it is for welders in the real world.

That foreman and I had just come back from Alaska, we built the city of Dillingham's new dock. He tried his best to sabotage my work there. So the project manager made me the welding foreman, then I was making $3.00 and hour more than him as a rigging foreman.:laughing: My crew was working 7/12s, his crew was working 6/10s. That really got his goat! At one time we almost went to blows over something I forget now. Trouble with construction, majority of the people running work don't have a clue how to weld, don't care to learn, and in their eyes all weldors are dead beats, because they sit on their a $ $ all day.

 

[jwmorris]

Depends on what the material is, what process and what I need out of the weld. Using TIG with cold rolled or stainless requires almost nothing, you can weld hot rolled doing nothing to it but you get better results knocking the scale off. Same goes for MIG or stick, if you have to pass X-ray you prep the material. I also generally apply anti splatter to the material before welding too.

 

[yomax4]

I just turn the Inductance back a click or two and let her bite. No grinding, no chemicals and no spatter either.. If you have an old school technology machine like a Miller Matic 252..You may want to do a little prep with the grinder.

 

[Arc weld]

I've never had a problem on new clean steel. Obviously if the steel has sat outside and is rusty you should clean it. You could always run flux-core if the steel isn't the cleanest. They make special flux-core for less than perfectly clean steel.

 

[Gary Fowler]

That inspector should have lost his license! New steel usually doesn't require any cleaning. For TIG and pipe welding it has to be real clean but most structural and general welding is done without any cleaning unless it is caked with mud or dirt. Minor rust or mill scale isn't a problem. S6 MIG wire has helped in this regard because it has more deoxidizers than the old standard S3 wire.

Just about everything you said there was inaccurate at least in my world and my former companies world of Quality in Workmanship. All metal requires at least a brush cleaning and most times grinding as power brushing many times wont remove mill scale which is iron oxide (same as rust to a weld)
I worked as a pipe welder for some years then into supervision and finally QA manager for over 25 years and if I caught a welder welding even structural attachments without cleaning the area free of rust/paint/ grease etc having windbreak and never any water or snow etc in the weld area he would be shutdown and possibly fired depending on if it was his first offence. All welding processes per welding procedures call for clean up of weld area back 1" from the weld joint. It not only makes for a better weld, it is easier on the welder as you have much less sparks and exploding metal from trapped debris in the puddle.

Can you weld over dirt etc when repairing farm equipment? YES but getting a proper weld while doing that is iffy with even the best welder. Unless the geometry is such that you just cant get any kind of cleaning tool into the area, it pays dividends to clean it up first. Just like ShieldArc said, weld a pass and grind out most or all of it when you don't do it right by cleaning contaminates and blocking off water and wind.

 

[Gary Fowler]

Depends on what the material is, what process and what I need out of the weld. Using TIG with cold rolled or stainless requires almost nothing, you can weld hot rolled doing nothing to it but you get better results knocking the scale off. Same goes for MIG or stick, if you have to pass X-ray you prep the material. I also generally apply anti splatter to the material before welding too.

When I was welding, I made every weld as if it were xray even if I knew it wasn't going to be. It doesn't take any longer to put on a good weld than a bad weld. In pipe welding, most xrays are random just for that reason as one never knew which one the inspector would choose to shoot so you had better make them all good. I welded as a pressure welder on pipe and just about every alloy known at the time and never had a bad xray for the reason stated above. Take the time to do it right and it is always much easier to weld.

 

[jwmorris]

When I was welding, I made every weld as if it were xray even if I knew it wasn't going to be. It doesn't take any longer to put on a good weld than a bad weld.

Actual weld time is going to be identical but the prep can take a lot longer. If I am making a coat hanger out of old rusty horse shoes, it's easy enough to go sand blast them in the cabinet to prep but there are other projects that are over kill like that and I just don't worry about the weld as much as of it were something important.

I just turn the Inductance back a click or two and let her bite. No grinding, no chemicals and no spatter either.. If you have an old school technology machine like a Miller Matic 252..You may want to do a little prep with the grinder.

I clean/or not the same if i am using an inverter machine with inductance and or a pulse control or an "old" style machine.