Taking the test
Posted: Sun Apr 26, 2015 1:40 pm
I worked for some of the largest power boiler contractors for many years as a welder and many of those years supervising the welding crews during construction or repair of the boilers. These were primarily coal burning boilers in power plants or chemical recovery boilers in paper/pulp facilities. During those years I took many, many welding test's, primarily boiler tube test's in the 6G position. For several of the companies I worked for I gave the welding test. These test's were generally 2" diameter, 220 wall, SA210 material. Here is a synopsis of how I gave the test's and instructed the welders. When a welder showed up to test I would meet him (or her in a few cases) at the sign up office and after finishing paperwork we would head for the test booth area. Basically here is what would happen then. Welders were told they have 4 hours to complete the test, take longer than that and we have a special job for you called wherever you find the next one because you won't be here. Here are your two coupons. Clean them up using the die grinders with flapper wheels, grinding discs, carbide xmas tree burrs. When clean place them in the angle iron jig (just a piece of angle iron tacked into a V position). Tack them up using a minimum of two tacks or a maximum of four tacks all between 3/4 - 1 inch long using TIG (these were primarily carbon steel coupons so we used ER70S2 or ER80SB2 wire. Filler diameter was the welders choice). Personally I always used 1/8" diameter wire on root passes when testing. After tacking up and feathering the ends of the tacks that is a hold point for inspection. I would look at their prep work to insure they had cleaned, positioned, and properly tacked the coupons in preparation for welding. Using a flashlight and mirror I would look at the root of the tacks to insure fusion and penetration. Requirements for penetration were flush or slight root protrusion, no suck back allowed. Occasionally a welder would be failed at this point but most passed.
After tack up inspection they placed the coupon in place and were instructed it was not to be taken down again until told to. They welded the root passes then and after that was another hold point for inspection. I would check the root passes for fusion and penetration. Tack welds had to be tied in and a uniform appearance necessary. Most welders passed this but some were "looked out" at this point. If I saw a single minor point that I did not like on the root they generally got one chance to repair the area "unless they had proved to be incompetent or a butthead in which case they went away". After passing the root pass portion they were told to either hot pass using TIG or weld it out using 7018. Again their choice (given that choice a welder that did not hot pass w/ TIG was either a very experienced welder or a damn fool). After welding out they could clean the coupon up with a wire brush and a half round file. That was a hold point for inspection. The coupon had to be filled w/ a minimum of three stick passes, no undercut allowed, appearance had to be uniform, a maximum of 1/16 cap height, no arc strikes outside the weld area. Welders that made it past this point were told to take down the coupon, mark it w/ their name and employee number and either leave it for Xray inspection or to cut four 1" wide strips for bend testing. Strips for bend testing were taken at the four 45 degree setions of the coupon. They cleaned up the strips using grinders and flap wheels on the outside area of the coupons to the flush point. The root pass side of the coupon was cleaned with a wire brush only. TIP: If you clean coupons for a bend test do not leave grinding marks that that run in the direction of welding. If you leave any marks make sure they run the long coupon length across the weld area not with it. Cross section marks will tend to facilitate cracks which leave you kicking horse turds down the road instead of getting the job. After coupon strips were prepped by the welder I would bend them. Two were root bend, and two were cap bends. These were bent approx. 120 degrees. Folks if you had any porosity or lack of fusion in your weld area they showed up in this test. They needed to be clean of any cracking and since these test's were ASME IX one spot of porosity less than 1/32 diameter would be permitted in one of the four coupons, no lack of fusion, no suckback of the root. Pass this point you were told to go home and wait for Xray exam (generally overnight results) or if it was a bend test and you passed to go the top of the boiler and your foreman would meet you there to put your butt to work.
For those of you that are nervous as a cat in a chinese food factory about taking your weld test this might give you a little insight of what to expect. Procedures and requirements change with every contractor or person administering the test but this is generally the way I went at it. Practice, practice, practice.
After tack up inspection they placed the coupon in place and were instructed it was not to be taken down again until told to. They welded the root passes then and after that was another hold point for inspection. I would check the root passes for fusion and penetration. Tack welds had to be tied in and a uniform appearance necessary. Most welders passed this but some were "looked out" at this point. If I saw a single minor point that I did not like on the root they generally got one chance to repair the area "unless they had proved to be incompetent or a butthead in which case they went away". After passing the root pass portion they were told to either hot pass using TIG or weld it out using 7018. Again their choice (given that choice a welder that did not hot pass w/ TIG was either a very experienced welder or a damn fool). After welding out they could clean the coupon up with a wire brush and a half round file. That was a hold point for inspection. The coupon had to be filled w/ a minimum of three stick passes, no undercut allowed, appearance had to be uniform, a maximum of 1/16 cap height, no arc strikes outside the weld area. Welders that made it past this point were told to take down the coupon, mark it w/ their name and employee number and either leave it for Xray inspection or to cut four 1" wide strips for bend testing. Strips for bend testing were taken at the four 45 degree setions of the coupon. They cleaned up the strips using grinders and flap wheels on the outside area of the coupons to the flush point. The root pass side of the coupon was cleaned with a wire brush only. TIP: If you clean coupons for a bend test do not leave grinding marks that that run in the direction of welding. If you leave any marks make sure they run the long coupon length across the weld area not with it. Cross section marks will tend to facilitate cracks which leave you kicking horse turds down the road instead of getting the job. After coupon strips were prepped by the welder I would bend them. Two were root bend, and two were cap bends. These were bent approx. 120 degrees. Folks if you had any porosity or lack of fusion in your weld area they showed up in this test. They needed to be clean of any cracking and since these test's were ASME IX one spot of porosity less than 1/32 diameter would be permitted in one of the four coupons, no lack of fusion, no suckback of the root. Pass this point you were told to go home and wait for Xray exam (generally overnight results) or if it was a bend test and you passed to go the top of the boiler and your foreman would meet you there to put your butt to work.
For those of you that are nervous as a cat in a chinese food factory about taking your weld test this might give you a little insight of what to expect. Procedures and requirements change with every contractor or person administering the test but this is generally the way I went at it. Practice, practice, practice.
