Questions regarding the welder qualification section
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I’m not quite sure about two issues; could some senior member please help explain them? ! Thank you! Question 1: For the welding joint between the lower head and the skirt cylinder, it is required to weld a root layer of 4–6 mm thick at the location of the lower head, with the skirt cylinder being welded onto this root layer. Should the welding position for the root layer be flat welding? Still the surfacing position? The surfacing locations are all those where corrosion-resistant surfacing is required; what to do if carbon steel is not available? Question 2: If a welder has obtained a certification for TIG welding, can the skills related to TIG welding and shielded metal arc welding be used separately? I think it’s possible, but GMAW positions cannot be used alone for welds that are welded on one side but shaped on both sides. But my colleague said that GMAW cannot be used alone; could some senior member please help explain this?
1 The welding positions include flat welding, vertical welding, horizontal welding, and overhead welding. There is no surfacing position. To use the flat welding position, using a swivel mandrel poses no problem. Cladding generally refers to the cladding of a corrosion-resistant layer. The surfacing shown in the drawings is likely inaccurate. 2 Stick arc welding certainly cannot be used alone for double-sided formed welds. When a welder obtains the qualification for TIG-MAG welding, it means using TIG welding for the root pass and shielded metal arc welding for the cover pass. There are two qualifications: TIG welding and SMAW (K), where K refers to welding with a backing plate. This shielded metal arc welding method cannot be used for welding without a backing plate, but it can be used when a backing plate is present.
Regarding the second question: can the qualification in shielded metal arc welding be used separately for double-sided welding? I am referring to backside root cleaning welding, in a structure where both sides are fully welded through. There is no backing plate on the first layer of weld, but this layer is removed during backside root cleaning; ultimately, each layer of the weld can be considered as if it had a backing plate.
A certification for welding with shims cannot be used for welding without shims. In other words, there is no backing plate on the first layer, so welding is not possible. Any other layer will work.
Kaozeli: Double-sided welding and fillet welding of test pieces and welded parts, as well as butt welds of welded parts where full penetration is not required and tube sheet corner joints, are all considered to be welds with backing. If it’s double-sided welding, can’t we use a welder’s position with a backing?