welder is expected to provide and use while testing. Then, specific hold points are identified. The first hold point is a confirmation the person being tested is the welder identified by the employer, a review of the WPS, the test rules, and that the proper test is being administered. The first tack weld isn’t made until the paperwork is in order. The next hold point is assembly and tack welding of the test coupons. All dimensions are checked to verify they are in accordance with the sketch included in the WPS. If preheating is required, it is checked at this time. Once welding has begun, the next hold point is a visual examination of the completed root bead to verify interpass cleaning has been performed and the proper bead profile has been produced. The next hold point is the completed test while the test coupon is still in the test position. Only after the coupon has been checked is the welder permitted to remove it from the test position. I also check the welding parameters while the welder is welding, but this function is not identified as a hold point. The test rules include some instructions regarding interpass cleaning. Structural tests on plate cannot utilize power tools. Hand tools including cold chisels, wire brushes, slag picks, files, etc., are allowed. Pipe tests allow the use of power tools for interpass cleaning and limited grinding. Welders who will be qualifying to AWS D1.5, Bridge Welding Code, are not permitted to use power tools or hand tools for improving the weld bead profile or interpass cleaning. All cleaning must be performed in the test position. Relax. Some of you are squirming in your chairs as you read this. I know what you are thinking: “There is nothing in AWS D1.1, Structural Welding Code — Steel, that prohibits the use of power tools for grinding or improving the profile of the weld bead.” I agree. However, I am administering the qualification test, and it is my signature on the test report. The client, i.e., the welder’s employer, will sign the certifying statement, but I see little value in “certifying” a structural welder who has to remove 50% of the 32 Inspection Trends / April 2011 weld deposited because the welds are at best marginal. I realize that’s my own philosophy, but that is why my clients retain my services. They pay me to be the bad guy and to do the dirty work. Acceptance Criteria Every welding standard has visual acceptance criteria that are unique to that standard. The testing regimen varies from one welding standard to another. I believe in offering a fair and level playing field to every welder I test. I have formalized the written acceptance criteria for each specific qualification test I administer. The acceptance criteria for AWS D1.1 are different from those of ASME Section IX or AWS D17.1. The welder is provided with a copy of the acceptance criteria that will be applied when his or her test coupon is evaluated. There are no secrets. Evaluation When time permits and it is feasible, the welder is present when the test coupons are evaluated. The evaluation includes the visual examination; preparation of the coupons, i.e., grinding the face reinforcement of the groove test; and the bending of the test coupons or breaking of the fillet welds. When possible, I let the welder do the grinding and provide the motive force needed to bend the test coupons or break the fillet weld — Fig. 2. Once again, personal philosophy plays a part in allowing welders to be part of the test piece evaluation. It gives the welders a sense that the cards are not stacked against them. The welders see how the tests are performed and how the test pieces are evaluated. It is just one more learning experience for the welders, and it serves as an important teaching aid should the coupons fail for some reason. They have a firsthand opportunity to see how a weld discontinuity affects the test results. Test Results Let’s face it, welders are not perfect. Occasionally, they do fail to pass the required tests. So what happens if the welder fails to meet the visual acceptance criteria or the guided bend test? The easy answer is to send the welder packing, but that is not the only response when a welder fails the qualification test. Welding standards usually have provisions that allow the welder to be retested immediately or after additional training. Many welding standards require the welder to pass two additional tests if he or she is administered an immediate retest or a single retest if additional training is received. The duration of the training is left to the discretion of the employer or the inspector. To ensure the welder qualification process does not become an exercise in statistics, I require the welder to provide two welded coupons that meet the visual criteria before allowing the welder to weld two new test coupons. Both welded coupons are required to pass the requisite tests. If one of the two test coupons fails, it is back to the training booth. The welder qualification program established for each client may differ somewhat depending on the specific requirements of the welding standard used. However, the similarities between various standards outweigh the differences. Regardless of the welding standard used, a systematic approach to welder qualification will mitigate opportunities for mistakes and misunderstandings between the welder and the individual administering the welder qualification test. ALBERT J. MOORE JR. (AMoore999@comcast.net) is vice president, Marion Testing & Inspection, Canton, Conn. He is an AWS Senior Certified Welding Inspector and an ASNT ACCP NDT Level III. He is also a member of the AWS Certification Committee and the Committee on Methods of Inspection of Welds. An Important Event on Its Way? Send information on upcoming events to Inspection Trends, 550 NW LeJeune Rd., Miami, FL 33126. Items can also be sent via FAX to (305) 443-7404 or by e-mail to mjohnsen@aws.org.
Inspection Trends - April 2011 - Spring
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