This article addresses a couple of questions surrounding the subject of weld reinforcement in welder qualification. I have tried to explore the intent of Section IX on this. Should the weld reinforcement be removed once welding of the welding performance qualification coupon is over? Must it be removed? Is it permitted to remove it?
Read on to know the answers to these questions, and do let know your thoughts in the comments section below.
Thickness of Weld Reinforcement
Can Weld Reinforcement Be Accounted For Determining The Deposited Weld Thickness Required By QW 452?
No. This is expressly prohibited. Reinforcement bead, either in test coupons tested by mechanical testing, or in those tested by volumetric testing, is not permitted by Section IX to be counted for the purpose of deposited weld metal thickness.
This is clearly stated in QW 351. Also, the General Note under Table QW 452.1 (a) notes that deposited weld metal thickness s the total weld thickness exclusive of the weld reinforcement. This amply clears the matter.
Interpretations IX-83-77 and IX-83-143 further confirm this.
Removal of Weld Reinforcement Before Testing
Should bead reinforcement be removed before testing of the sample for performance qualification?
Should reinforcement bead be removed during the preparation of samples for testing? Is it advisable/mandatory/prohibited/permitted?
QW 351 says that the thickness limits given in QW 452 are to be considered exclusive of any reinforcement. However, should it be removed? Or, must it be removed?
Let us see what Section IX mentions regarding this matter. We will see for various tests, such as RT, tensile test, side bend test, one by one. Please note that the following discussion can be taken for procedure qualifications too.
For RT, QW 191.1.2.2, “Weld reinforcement may be removed or left in place but shall not be considered when determining the thickness for which the welder is qualified.” This means that removing the reinforcement is a choice.
QW 462.1(a), (b), (c) for tension test indicate that the weld reinforcement shall be ground flush with the base metal, meaning that reinforcement bead must be removed. This is given perhaps because the reinforcement bead would resist uniform tension in the specimen, and might cause the breakage to happen in the base metal (instead of a possible breakage in the weld metal), which would be misleading.
QW 462.3(b) for longitudinal face bends and root bend specimens also indicates that weld reinforcement shall be ground flush with the base metal, meaning that reinforcement bead must be removed. This is given perhaps because presence of reinforcement in a longitudinal face/root bend specimen would mean that only the reinforcement gets subjected to highest tension during the bend test.
That is not desirable; the top face of the weld in conjunction with the base metal should get subjected to the tension in fact.
QW 462.2 for side bend specimens, and QW 462.3(a) for transverse face bend and root bend specimens, indicate that the weld reinforcements may be removed during specimen preparation, meaning that it is a choice.
Generally, to give it the best chance of passing in a transverse oriented bend test, the reinforcement is removed from a test coupon. Although it is not mandatory, it is advisable to remove weld reinforcement from a test coupon if it has to provide bend specimens in transverse direction.
Interpretation IX-78-39 provides interesting similar insights in the matter.
Miscellaneous Observations
Although this article is about welder qualifications, following is a little something about the matter of reinforcement in procedure qualifications.
Reinforcement In Procedure Qualification Coupon
Section IX clearly mentions conveys that thickness of reinforcement is not to be counted for welding performance qualifications. However the same has not been told for welding procedure qualifications. What is Section IX’s intent on this?
This was made clear in 2019 edition of Section IX. A line was introduced in QW 202.2 saying “The thickness, t , of deposited weld metal in QW-451 shall be exclusive of weld reinforcement.” This settles the above question.
Before testing of the test coupon, it is best that the reinforcement is removed and the weld is made flush with the adjoining base metal.
So, these were some of the observations regarding weld reinforcement on a weld coupon. I hope this brought some clarity to your understanding on the subject. Do let know your thoughts on this, in the comments section below.
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