Pipe Welding And How To Pass A SMAW 6G Welding Certification.
The pipe welding techniques used and the procedure is also identical to the ASME section IX pipe welding certification. Since welding pipe in the 6G position covers all of the pipe welding positions the information on this page can be applied to welding pipe in any position. The 6G welding certification is far from easy to pass and has a lot involved. Because there is a lot involved this page is pretty long and I also took a lot of pictures. I do want to say I barely passed this certification and came very close to failing it. When comparing structural welding certifications to pipe welding certifications there is a major difference. Structural welding is one position and rod angle at one time. The 6G position is a combination of all of the structural and pipe welding positions, with a full transition between them all, plus a hard side and easy side, depending on if you are left handed or right!
Since pipe welders can (some not all) earn a doctors salary this is the most wanted welding certification! So obviously a lot of welding students want to have this welding certification before finishing welding school. I hope to give any student welders interested a head start on getting ready to pass this 6G certification. The one piece of advice I can give about learning to weld pipe is, get your structural welding skills down first. Otherwise it will take more time to learn to weld pipe!
AWS B2.1 SMAW 6G Pipe Welding Procedure Specifications
- Welding Process. SMAW
- Position. 6G Fixed Position
- Weld Progression. Up
- Backing. No
- Current/Polarity. DCEP
- Root Opening. 1/16 to 1/8
- Grove Angel. 60 degrees
- Material/Spec. A 106
- Thickness. (pipe/tube): Groove (in) .280
- Notes. Sch. 40 Pipe
- Filler Metal Class . E6010Rt/E7018Fl
- Other Filler Metal Class. Rt 1/8, 3/32 Filler
Practicing To Pass a Pipe Welding Certification
When starting this web site I had just gotten back to welding for a few months while working in a fabrication shop. I was lucky I got that job because after 12 years of not welding, my welds sucked! Within about 3 months in that shop I was one of the best MIG welders and already the lead fabricator.
A long story short is I was going broke working there, so I signed up for a welding class to take my 6G welding certification and get a better job! At my last job I MIG welded pipe and plate with some Stainless Steel Stick welding in all positions. Signing up for the class I started practicing in the 6G position. My progress was OK and I felt I was ready to pass the 6G pipe test in a week or two. At the time I poked around looking for work and got a few good offers. Naturally I quit my job to focus on school, get my life back in order, and build this site as a selling point for my resume.
What I did not expect is to hit a wall while practicing for the 6G pipe test. About a month went by and my welds visually did not get any better (it was a part time class). I got desperate and decided to get whatever welding certifications I could pass then. So I did my 3G MIG cert, then my 3 and 4G combo Stick cert, followed by 3G FCAW cert.
Being unemployed I kept going to school and went back to the 6G pipe test. All of a sudden the 6G position became easy to weld in. I wised up and did the basics again. I did 1 through 4G plate with an open root and found my trouble spots. Then I practiced 2 and 5G open root pipe welds followed by the 6G pipe. After that I took the test and passed it.
The point is, if you want to pass a 6G pipe test practice the basics first. Don’t rush into it like me. I always say rushing is for fools and here I am one of them! I thought because I have done it before I can still do it now. If there are any positions that you may have trouble with, it is easier to find them on plate, and fix the problem there!
How To Bevel Pipe and Coupon Preparation for A Welding Certification
The preparation of the pipe coupons was simple. The way I received the pipe coupon was a single piece of pipe. The first thing I did was cut it in half on a band saw and then beveled it on a pipe beveling machine.
My next step was to grind off the oxidation from where the bevel was cut, followed by grinding the mill scale off of the outside of the pipe a minimum of one inch back, then the inside of the pipe about a quarter of an inch back. Finally checking the bevel angles with a protractor. The angle of the bevel was right where it needed to be. Next I put my land on the bevel; I used about a 1/16th land. I used a grinder to make the landing and pretty much eyeballed it. After I was finished putting on the landing I took a 1/16th of an inch thick piece of scrap metal and used it to measure the landing.
Pipe Coupon Bevel Inspection
The welding machine set-up is a critical part for any type of welding and when it comes to pipe it is the most important! The machine I used for the 6G Pipe cert was a Miller DialArc 250. It’s a real simple and nice Stick welder but unfortunately it does not have a hot start feature. When setting up my machine for the 6G position I did notice I did get some restarting trouble in the same areas. Besides the lack of the hot start feature the machine ran real nice.
Welding Machine Set-Up For Tack Welding Pipe With An E6010
When setting up the welder for a 1/8 E6010 open root weld I used 90 amps for the tack welds. I did this because the pipe and electrode were not pre-heated enough and needed this amperage to penetrate properly. On the actual root I used 83 amps to weld it all the way out. The lower amperage was no problem because I piggy backed all of my tacks, while the electrode and the pipe had enough time to pre-heat. If the amperage was higher the keyhole would be too big. When setting a welding machine to do an open root weld you need to find amperage setting that is hot enough to open up a keyhole fast but not too hot that the keyhole gets too big! The main thing to look for when setting a welding machine to run an open root weld is for the amperage to be high enough that the electrode does not stick when testing it on a piece of scrap metal. The amperage setting should be high enough for it to barely weld without sticking.
Pipe Welding Machine Settings For The Fill And Cap With An E7018
Originally I tried a 1/8 E7018 rod and found it was total overkill for a 6” schedule 40 pipe, so I turned to the 3/32 E7018 electrode, and it worked way better. The amperage I used was 95 amps and the rod ran real nice on the hot pass and cap! This setting in any position puts down a real nice bead!!
How To Tack Weld A Pipe For An Open Root Weld Joint
The set-up of the pipe coupons was done on a V Block. If that’s what the proper name of it is. Basically I used an angle iron to lay the pipe coupons on. It keeps the pipe coupons inline and makes it easier to tack. Then I took a 1/16 cutting wheel to set the root opening. Once the pipe was aligned properly I put in the first tack. Now once the tack cooled the pipe was out of alignment so I used a hammer to get the root opening even again. The tack welds will mainly shrink on the keyhole side of the tack. The next tack was done on the opposite side of the pipe. I had to tap the pipe a few times to get it to line up properly. I kept repeating this until I had four tacks. The first tack is in the 12 o’clock position, the second in the 6 o’clock position, the third in the 3 o’clock position and the fourth in the 9 o’clock position. All of the tacks were about 3/4 of an inch long. Finally I checked to root opening with the 1/16 cutting wheel and as usual the tack welds shrank. So I used the cutting wheel to open up the root opening. This is one of those tricks that not a lot of people will tell you about setting up open root welds. The cutting wheel will almost always make a perfectly even root opening! That is the main trick to passing any open root welding test! After I was happy with the tacks and root opening I feathered all of the tacks edged with the same cutting wheel.
Inspection Of The Pipe In The 6G Fixed Position
Once I got the pipe coupons tacked up, then I put them in the arm that holds the pipe in place. I took a level and set the pipe at 45 degrees. Next I set the height of the pipe to where I wanted to weld it. I prefer to weld the bottom half of the pipe on my knees and that also gives me a more stability then standing. Once everything was in place and I tightened the arm and called the welding instructor.
The welding instructor rechecked the root opening and then the position of the pipe. He then marked the arm in a few places to make sure the pipe was not moved during the test. This was done because the procedure states:
“Now the test will be placed in the fixed position. The test piece will be marked in position with a marker and the inspector may see the test anytime during the testing. (DURING THE TEST, THE PIECES SHALL NOT BE MOVED IN ANY DIRECTION AND OR REMOVED FROM THE TESTING PLACE WITHOUT THE INSPECTORS APPROVAL.)”
Open Root Pipe Welding Techniques
The 6G open root was done with a 1/8 E6010 electrode at 83 amps using a whipping technique. Most of the time I was dragging at about 5 degrees while pointing the rod to the center of the pipe. If you do not always point your rod to the center of the pipe and keep the keyhole centered you will get a lack of fusion. In the event that the keyhole is closing up you need to lead the rod at about 5 to 10 degrees. The hard part of the root is the bottom half of the pipe.
Below are some basic guidelines for trouble shooting open root welds. Above all, when you are not sure about the root, STOP WELDING at once!
Keyhole Getting to Big
- Increase the angle of the drag .
- Lower the amperage.
- Start to whip the rod in longer motions.
Keyhole Closing Up
- Start pushing the rod forehand toward the direction of travel.
- Increase the angle of the push.
- Raise the amperage.
Concave Root Or Suck Back On The Inside Of The Pipe
- Push the rod inside the pipe so the arc is in the inside when welding. The sound of the electrode burning should be coming from the inside of the pipe.
- Slow down your travel speed.
- Start to use a Very tight whip that is almost a slow steady motion. You want to give the electrode enough time to properly fill the root.
- Lower your amperage.
- Keep the keyhole smaller.
Excessive Root Weld Reinforcement
- Increase your travel speed.
- Use a longer whipping motion.
- Pull your electrode further out of the root when welding.
- Lower the amperage.
Restart Trouble Or Tie In Lacks Fusion.
- Feather all tacks and restarts with a grinding wheel.
- Piggy Back all restarts and tie ins at least a 1/4 of an inch.
- Pause for a second on all feathered edges to burn in properly.
- When tying in don’t stop welding until you have penetrated the tack and covered most of it.
How To Do An Open Root Pipe Weld In The 6G Position
The first part of my root was from the 6 o’clock to the 9 o’clock position. Since I am mainly right handed this is my hard side for the root. What makes it difficult is that I am welding from right to left, so the handle and electrode naturally block my view of the keyhole. What I did was position myself in a way that I can see the keyhole at all times.The down side is it is very difficult to stay in that position without getting any muscle cramps. To start the weld I piggy backed on the 6 O’clock tack while preheated the electrode on the tack. Then slowly whipped the rod until I was on the feathered edge of the tack. Once I could see the weld burning into the feathered edge I paused for a second pushing the rod inside the bevel to let the arc shoot up enough filler metal to tie into the tack properly. After that I was just a simple whipping motion until I got to the 9 O’clock tack. When I got onto the tack I kept welding until I was past the feathered edge.
The second rod I used was done on the root from the 9 o’clock to the 12 o’clock position. Before starting to weld I used my grinder to clean up the 9 o’clock tack that was piggy backed from the previous weld. Once it was cleaned up I piggy backed that tack and started whipping. When tying into this tack I did not pause too much. On the upper half of the pipe gravity is in your favor. In this case it is easy to have too much penetration on the inside of the pipe. The technique I used was just a whipping motion while dragging the rod about 5 degrees, and above all, the electrode needs to always be pointing to the center of the pipe. When coming up to the 12 o’clock tack I piggy backed half way over it.
My next root pass was from the 6 o’clock to 3 o’clock position. It is the easy side of the bottom half of the root if you are right handed. This is because you can easily see the keyhole for right handed people. On this side of the weld I used my left hand to lean on the pipe while leaning the electrode on my thumb to guide the rod. Once the electrode burned short enough I slowly took my left hand off of the pipe and went to holding the handle with two hands. Before starting to weld I ground the 6 O’clock tack from the previous piggy back restart. Just like the other bottom half of the pipe I let the rod preheat and paused and pushed the rod into the root when burning into the 6 o’clock tacks feathered edge. After that it was just a whipping motion and then piggy back onto the 3 o’clock tack.
My final root pass was done from the 3 o’clock to 12 o’clock position. Before starting I grinded down and feather the edge of the 3 o’clock tack where my last weld stopped. On this side of the pipe I had to sit on the table to get a good view, otherwise I would not be able to weld 90 degrees in a single pass. I have a bad habit of making long welds even when I can’t see where I am going. In most cases shorter welds are fine as long as you grind and feather your restarts. Just like the other top half of the pipe I piggy backed the restart onto the tack then let the electrode preheat, burned into the feathered edge, followed by using a whipping motion up to the 12 o’clock tack. Once I got onto the 12 o’clock tack I piggy backed half the tack.
Weld Inspection Of The Open Root
The root inspection was done after I finished the root. I did have a repair that I had to grind out and open it up with a 1/16 cutting wheel. I did the repair because there was a lack of fusion due the pipe root opening closing up from the weld shrinking. Repairing an open root weld is pretty easy if you know what to do. First the repair area of the weld needs to be grinded to the same thickness and approximately the same dimensions of the original bevel. Next you take a cutting wheel and reopen the defective root area. Then all you have to do is re weld the root and that is it. I will not show it because that might make my root no longer passable. But I will say that area was part of the bend test! Once I finished the root of the weld I cleaned the weld penetration up as much as I could using an electrode to chip off the slag. Most open root welds look like they penetrated properly when the slag is covering it. It’s one thing to have a nice looking root with slag on top of it but another to see the actual weld! The root was inspected thoroughly using a mirror like the dentist uses to check your teeth. My root pass was inspected and I got to move on! The rules for passing a root inspection are as follows:
“The root of the weld shall be inspected, and there shall be no evidence of cracks, incomplete fusion, or inadequate joint penetration. A concave root surface is permitted within the limits shown below, providing the total weld thickness is equal to or greater than that of the base metal. The maximum root surface concavity shall be 1/16 in. (1.6 mm) and a maximum melt-through shall be 1/8 in. (3 mm)”
Hot Pass Pipe Welding Technique
My hot pass or filler pass was done using a weave with a 3/32 E7018 electrode. The technique I used was to hold the sides until the weld washed into the bevel. The upper part of the bevel was held about 2 seconds and the bottom was held for about 1 second. This is the easiest part of the welding certification.
Hot Pass In The 6G Position
Before putting in the hot pass I grinded down the roots surface. When it comes to welding certifications some inspectors do not allow grinding at all but with the E6010 root they almost always allow to grind down the root. Most of the time everyone piggy backs there tacks, so you will have a few lumps on the outside of the root from the restarts. When it comes to grinding down the roots surface on critical joints it is always allowed.
Here is are the pictures of my hot pass. As you can see the bevel is mostly filled and there is no slag on the edges of the bevel. When putting in a filer pass the slag should come off pretty easily! If not, that means you are not holding the sides long enough and there is a possibility of slag inclusions.
Pipe Welding Techniques For The Cap
The cap was also done with a 3/32 E7018 electrode using 3 stringers beads to put in the cap. The technique to putting a half decent cap in is to spread out the weld. That is a very tight side to side motion, basically a tight weave. This is something I did not do in the beginning and disagreed with the welding instructor who conducted this test. Since taking this welding certification I have focused my efforts on spreading out the weld when using an E7018 electrode. I should have listened to someone who has made a career of welding X-Ray quality welds is very difficult conditions. Since I took this test and passed it at the bare minimum I have come close to a almost next to perfect cap. The last 6G weld test I took was for Fluor and I was allowed to take pictures. They are posted at the end of this page.
Some basic guidelines for welding the cap are as follows:
- Keep your electrode angle pointed to the center of the pipe at all times with very few exceptions.
- Keep your arc length as short as possible.
- If possible, drag your electrode slightly no matter what the position is. Most people will disagree with this but it works for me because it keeps the slag behind the puddle.
- Only move forward and side to side with the electrode otherwise the weld will become rough.
- When the pipe gets to hot let it cool down or put on a vice grip to lean on.
- Make sure you fuse the bevels edge.
- Overlap stringer beads from at least 25% to a maximum of 50%. The goal is for the weld to have a single profile when finished.
The Cap Weld In The 6G Position
Before putting in the cap I cleaned the hot pass with a wire wheel and hit it with a grinder. I did not have to use a grinder, but if I can, I will. It’s just safer if you are allowed. A light grinding of the surface will expose any trapped slag or porosity.
The cap was done from the bottom to top. There is not much to the cap except make sure you fuse the edges of the bevel and keep spreading out the weld. The pictures below are of the first stringer bead I put in. The weld is a little rough because I would sometimes pause or move the electrode slightly back into the weld crater. This is solved by only moving forward and side to side.
These pictures below are of the second stringer bead. The weld got a little smoother because I was spreading the weld better. On the forth picture you can see where my electrode got stuck on the top of the pipe. I had to grind that spot before restarting there. If your electrode starts sticking try not to long arc it. If you do you will end up with porosity in the weld. The best way to keep the electrode from sticking is to keep the rod moving.
The last stringer bead was done once the pipe cooled down enough for me to lean on it. On the last stringer bead I made sure I spread the weld over the edge of the bevel and into the second stringer. Those are the pictures below.
Visual Inspection Criteria For A 6G Pipe Welding Certification
This visual inspection is the hard part of the test! Passing a bend test is easy but the visual part is much harder. I know this because I have bent some of my practice coupons that would not pass the visual examination, including coupons that I thought would fail. Not one coupon broke or opened up more than the procedure allows.
To begin the welding instructor conducting my test gives nobody any slack and goes sticky by the book! This is where I got lucky! He follows the rules and allows the use of a grinder to do repairs. Basically all of my welds had to be exactly within the AWS acceptance criteria. My best friend all of a sudden became the grinder. Overlap, arc strikes, and anything that is less than the procedure states is an instant visual weld rejection. I cleaned up my welds with a 1/16 cutting wheel because it gives total control unlike a grinding wheel. The rules state you are allowed one repair after the weld inspection, so I checked my weld thoroughly and cleaned up anything that was not suppose to be there. As long as you do your repairs before the weld is inspected then you have one repair left if you need it. In the end I passed the visual based on the AWS acceptance criteria. The two big criteria are no undercut over 1/32 of an inch and no excessive weld reinforcement over 1/8 of an inch.
Test Coupon Preparation For A Pipe Welding Certification
Preparing of the test coupons was done following the AWS procedure notes. First I marked the pipe with a template. The template marks the pipe from the 1 o’clock to 12 o’clock positions. Next lines are made to cut out 4 coupons. The coupons need to be a minimum of 1/ ½ inches wide otherwise they will be rejected. There will be two root bends and two face bends. The root bends were at the 11 o’clock and 4 o’clock positions. The face bends were on the 2 o’clock and 8 o’clock positions.
The coupons are then cut on a horizontal band saw. Some of the coupons did not come out even because the band saws vice had a worn out part that needed to be replaced. But again the coupons were a minimum of 1 ½ inches wide so they were accepted.
Now the pipe is cut into bendable sections. The sections are two root bends, two face bends, and the larger pieces are the alternate coupons. All of them are marked to identify the proper sections of the pipe. R stands for root, and F stands for face, and the number refers to the position that the coupon was welded in. The pictures below are showing the root of the weld and the cap of the weld.
Once you have the test coupons they need the center of the weld to be marked with a center punch. This is done to make sure the weld area is being bent.
Finally the cap and root of the weld need to be grinded. When grinding down the weld reinforcement you are not allowed to go below the surface metal. On my root I had some concavity. This must be left alone. At first I thought undercut and concavity will cause the test coupon to fail. That is very far from the truth. So if you are taking a welding certification and have some undercut, don’t worry about it as long as your weld is solid! The pictures below are before removing any weld reinforcement.
The rest of the pipe is there for an alternate bend test in the case a coupon fails. If a coupon fails it must be within the AWS alternate rules notes. The most common allowed failure is a corner crack that has no evidence of slag inclusions.
Below are the prepared root and face bend specimens with the weld reinforcement removed by a grinder. On the inside of the root specimens you can see a little undercut and concavity.The edges of the coupons are also slightly rounded with a sander. This is done to keep the corners from cracking. The rules state you can round the edges up to a 1/8 inch radius. Now the root and face test specimens are ready to bend.
6G Guided Bend Test Results
The bend testing was a nail biting moment. The coupons are put into the bend testing machine and they get bent. It’s that simple and this is where you really find out how solid your welds are! The pictures below is of my first face bend. This one passed without any problems.
Here is the second face bend and this one came out fine too.
Now the first root bend coupon. It went through and there is a opening in the center of the root. This coupon needs to be examined closely to determine if it is acceptable. At the moment I don’t know if I passed or failed!
Here is the second face bend coupon coming through. In the third picture you can see there is some thing there and the forth shows it clearly. This coupon is fine because it did not open up and that is just some concavity from the root.
This was a nail biting moment. The instructor took the first root bend coupon that had the opening in it and put it under a magnifying glass. He used a digital micrometer and measured the opening. It came a few thousands of an inch less than the acceptance criteria allows. When taking the picture on the right I was real nervous. It’s one of those moments you have no control over.
There it is! The basics of pipe welding and that is how I passed the AWS B2.1 6G open root pipe welding certification.
An Actual 6G Pipe Welding Test For A Job
Since I have taken this welding certification I have been at the Fluor craft welder training center for a long term job interview and an upgrade your welding skills course. So far I have almost perfected my stick pipe welding since taking this test and am working on my TIG welding skills. The test they give is a E6010 root with a 1/8 gap and landing, a two stringer fill, and a two to three stringer cap, using a E8018. The other main difference is, no grinding allow except on the root. They do not allow any concavity on the root or imperfections on the cap! The bottom line is you must weld better then the ASME code allows! Here are some pictures I took at the training center located at Greenville Tech in SC. My welds have seriously improved with just a little more practice and it is only getting better! This is a great program if you are accepted into it!