Posts Tagged ‘pipe welding’

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How to determine what to do when the weld goes bad!!

October 13, 2008

Someone asked me how I know what to do when the weld takes a turn for the worst? Really after years of experience and teaching you learn to train your eyes and mind of what problem areas of a weld look like.

That is the benefit of this course. I can relay to you the benefits you can receive from my years of painful mistakes and errors I have learned not only from my own mistakes but the mistakes of those around me.

One of the videos recently published from the crud trap series showed my weld gap opening up and the metal running the risk of falling in on the bevel creating what is technically called excess penetration.

Excess penetration is caused from pushing too much metal to the interior surfaces on the inside of the pipe. This is usually caused from staying too long in one spot while welding. The combination of too large a gap and high heat can also attribute to excess penetration.

It is almost a guarantee that young welders at some point will face this common problem. 

The way around this is to try your best to evenly match the pipe bevels and the interior surfaces of the pipe.

An even gap all the way around the pipe makes life a lot easier. 

The problem I faced in the video you saw on the crud trap series was a hand beveled pipe surface.

The hand beveling is almost always inferior to the factory or machine bevel. When two factory bevels are matched the gap is consistently matched and makes the weld path more uniform. 

Because of this the heat range won’t need to be adjusted as with an uneven hand bevel. 

What happened to me on the crud trap is that the gap was inconsistent leading to my keyhole opening up to much and the high heat became my enemy. The keyhole opened up and the edge of the pipe was burning up before I could deposit metal. 

When this happens if you don’t stop immediately and make some type of adjustment more than likely you will do a few of these things if not possibly all of them.

1. Burn the pipe bevel up and open up the gap

2. Leave excess metal in the weld path because you stay in the big gap too long trying to fill the crater

3. Lose the keyhole you had to the canyon that is created.

4. Draw back the rod while still welding because the heat is too much to handle now and by doing that you      may not penetrate the weld and leave undercut on the interior of the pipe surfaces.

Either way it goes the thing to do is stop welding. You can change the heat slightly bringing the amps down usually 5 to 10 amps depending upon your skill and the problem. Maybe more, maybe less.

Stop welding and let the pipe cool off. Don’t push the rod into the bevel as much and begin to butter it around skipping over the bevel more causing less penetration.

The only way to be certain about what you do on the inside of the pipe is to make slight adjustments, weld a little, then look inside the pipe with a flashlight to see what you are doing. Hopefully if the pipe is not completely closed you may be able to look through the bevel to see the interior weld. You may also be able to see the interior weld with a mirror and light from the outside if the pipe piece is not to long or closed up.

When the gap opens up grind as little as possible. The last thing you want to do is take away more of the bevel now. If the pipe is glowing red where you can see it after pulling out of the keyhole and the keyhole appears to grow then let it cool and turn down the heat.

I hope this all makes sense. If it doesn’t you know I will try to clarify it or come at it from a different angle.

Leave a comment and let’s talk further. Until then. Stay behind The Welders Lens.

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The Stick Rod Series

June 27, 2008

Hello again from The Welders Lens, I hope this article finds you without burnt eyes or some other welding trauma.
Today we are going to start our  discussion about the anatomy of stick rod or arc welding with flux coated rods (electrodes).
Of course there are many types of stick rods but the best place to start is with a fast freeze rod.

Fast freeze rods are in a category that has been the foundation for stick rod welding. They are still an industry standard in many places. I have worked for companies that don’t use these rods in their process as a root metal, but most do. When we talk about root metals we are talking about those metals that are always the first metals to be applied to a weld joint, whether it be  pipe welding, plate welding , tube welding, structural welding, etc.
When we speak of this type of rod we are almost always talking about basic carbon steel (also known as black iron or mild steel).
Fast freeze rods have the ability to cool rapidly even while the weld process is in motion.
Imagine stacking dimes on top of one another with slight overlap from one dime to the next. Like a row of fallen dominos

Now this of course would be a flat continuous weld. Each time in welding with a fast freeze rod the rod is moved slightly forward and then back into the original puddle. As soon as you move forward with the stick rod the metal that has been deposited behind the rod is already becoming solid thus applying the term fast freeze. There is some ability to drag the rod without a great deal of movement, but because of the nature of the rod and its design, it wants to solidify rapidly so to prevent a great deal of build up when depositing the metal, you will naturally move the puddle more than some other rods.

The tighter the laying of one dime upon the next signifies good weld continuity. One thing that must be observed with this application is the tendency to undercut the areas of existing weld joint with the new metal that is being layed on top of it. When you step the rod out of the puddle, the area you move ahead to is being dug into by the action of this rod. That is why you step the rod back into the last dime of weld filling in the areas that have been dug out by the rod as it was moved ahead.
This type of rod has a great digging effort with it.

One tip of advice about this type of process is this: “Don’t be afraid to leave enough metal in the existing weld path before moving ahead”. Beginners especially have the tendency to move ahead to fast before depositing enough metal to prevent undercutting the parent metal (existing metal). Undercutting is a term that simply means the weld metal that has been depostied was not enough to flush out the weld with the surrounding surface. Normally, the weld deposited from the rod is enough to make the new weld higher or fatter than the original material. When the metal deposited during the welding process is shy or not enough, the newly deposited metal leaves a jagged edge next to the new metal instead of a nice rounded effect.

6010 electrodes, 7010 electrodes, 8010 electrodes, shield arc 85, 6011, 6013 are all fast freeze rods, just as some examples.
These rods are designed to dig into the parent metal and give good penetration. It is good on rusty metals and metal that is not very clean. Old material that has corroded over time, etc.

One trick you can apply with this type of rod is this: The polarity can be switched when welding this rod allowing for less penetration or digging as it is being welded.
Sometimes on thin metal or metal that cannot hold up to a great deal of scouring effort by the norm of these rods can be overcome by this little trick.
Make the ground positive and the hot lead negative (reverse polarity).You will find that the sound is a bit different while welding than it normally would be. You will also find that the welding rod does not have the tendancy to dig or penetrate as much.
This is a trick that comes in handy, especially when working on thin metals.

I have found for myself that these rods run smoother on a slightly higher heat than you might feel comfortable with. Running a hot puddle is better and becomes easier to handle the more you practice with it.
These rods can be run either uphill from bottom to top on a vertical plane or top to bottom on a verticle plane. There is more movement usually on the uphill and more dragging or leading on the downhill. They are actually all positions rods. Flat, overhead,vertical,horizontal,arkansas bell or 6g which incorporates all of the positions within the weld path.
Normally any pipe test you will ever take will be in the 6g position. There are some exceptions. One of the tests that I never liked taking was a fixed jig test.
This test simulates an actual field weld that will have to be made on the job. They can be a nightmare.

Heat, travel speed, and rod angle are the 3 most important factors when welding with stick rod.
I said heat, travel speed, and rod

One thing that does not usually hurt the stick rod category is wind. It has to really be blowing inorder to hurt the fast freeze series of welding rods.
Some of the rods I mentioned earlier are AC rods and some of them are DC rods. Keep that in mind when choosing your rod.
I have another article coming on that.

Well that’s all the time on this article.

Thanks from the author.