Understanding of the scope of application of NB/T 47014-2011
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Dear senior colleagues, I’m new to this field and am currently working on welding process qualification. I don’t quite understand the scope of qualification as specified in NB/T47014-2011. I hope you can kindly offer me some guidance: 1. In paragraph 1 of clause 6.3.3 on page 40 of NB/T47014-2011, it states: “When two or more welding methods are used for the same weld, or when there are differences in important factors or supplementary factors related to the welding process, qualification can be carried out separately for each welding method (or welding process).”； Two or more welding methods (or welding processes) can also be used to weld the test pieces for combined evaluation. ” For example, if I need to weld a steel pipe that is 20 mm thick and plan to use a combination of TIG welding for 4 mm and shielded metal arc welding for 16 mm, with no requirement for impact resistance, and I want to evaluate these two welding methods separately, then for the TIG welding evaluation, should I choose a test piece thickness of 2 mm or 10 mm? The same question applies to shielded metal arc welding: should the test piece be 8 mm thick or 10 mm thick? ； 2. Paragraph 2 of clause 6.3.3 on page 40 of NB/T47014-2011: “When a welding process that has passed the combined assessment is used for welded parts, one or several welding methods (or welding processes) may be employed, provided that its critical factors and supplementary factors remain unchanged.” Only the base metal thickness of the test piece evaluated using any one of the welding methods (or welding processes) is required to determine the effective range of thicknesses for the base metal of the composite evaluation test piece. ” The next sentence in this passage is not easy to understand; I hope the seniors can help explain it. If I have already conducted a welding procedure qualification for a test piece with a thickness of 20 mm, using a welding process of \"TIG welding 4 mm + SMAW 16 mm\", with no impact requirements, what is the range of base metal and deposited metal thicknesses covered by this qualification? My understanding is as follows: the thickness range of the base material is 5–40 mm, while the thickness range of the deposited metal is 0–8 mm for TIG welding, and 0–32 mm for shielded metal arc welding. In other words, when only TIG welding is used as the welding method, this assessment can be applied only when the thickness of the base material is between 5 and 8 mm; it cannot be applied for thicknesses less than 5 mm or greater than 8 mm ； When only shielded metal arc welding is used, the base metal thickness range is 5 to 32 mm; thicknesses outside this range cannot be covered. Is my understanding correct? I would appreciate it if the seniors here could give some guidance on these two issues. Thank you!
The first and second paragraphs are not separated; the first paragraph discusses how to conduct and carry out the evaluation, while the second paragraph explains the scope of that evaluation. For the first paragraph you mentioned, it’s fine to choose boards of 2mm and 8mm; understand it that way for the second paragraph. Personal understanding
Thank you for your reply. But logically, when using a 2mm thick plate for evaluation, isn’t the root metal coverage range only 1.5 to 4mm? A 20mm thick plate wouldn’t be able to provide such coverage, right?
This post was last edited by jnrx on 2015-9-21 08:18. Well, you’re right; I misunderstood it
For 20mm thick plates, use 4mm TIG and 16mm SMAW. No impact requirements. . The evaluation is as follows: 13mm with full TIG, and 38mm with full SMAW. In this way, by combining the two evaluation methods of TIG+SMAW, the base metal thickness that can be used ranges from 1.5 to 200 mm. The applicable metal thicknesses are: 0–26 mm for TIG and 0–200 mm for SMAW. As for the choice you mentioned, for a 20 mm thick plate, you should use 4 mm thick material for TIG welding and 16 mm thick material for SMAW welding; no impact resistance requirements apply. . The thickness of TIG should be at least 10 mm, and that of SMAW should also be at least 10 mm.
Thank you, I understand it the same way; although I really would like to interpret it as something else
The two evaluation combinations of TIG+SMAW use a base metal thickness of 1.5–200; the applicable metal thicknesses are 0–26 for TIG and 0–200 for SMAW. Should the thickness of the base material used here be 5-200?
Yes. . A 4mm TIG welding assessment should also be added
Teacher, is this the correct way to understand the second question? I am also troubled by this problem