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Destructive Weld Testing

Visual Inspection Criteria For A 6G Pipe Welding Certification

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6G Pipe Finished Welding Right Side 6 to 12 o’clock (view 2)

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.

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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.

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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.

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Finally the cap and root of the weld need to be ground. 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.

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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.

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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.

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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.

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Here is the second face bend and this one came out fine too.

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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!

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Here is the second face bend coupon coming through. In the third picture you can see there is something there and the fourth shows it clearly. This coupon is fine because it did not open up and that is just some concavity from the root.

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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 thousandths 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.

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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!

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