Definition of Class D weld thickness for the takeover and shell

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This post was last edited by yinmaizi on 2024-12-28 at 11:03. The definitions of weld thickness for the joints and the shell are easily overlooked, which can lead to omissions in the heat treatment process. 1. This is the definition as per GB/T150-2011 version, after corrections, and does not take into account the thickness of the nozzle. 2. This is the definition in the new version of GB/T150-2024, which includes fixed-type and plug-in types. 3. This is the relevant description in GB/T30583-2014. 4. Instructions for compilation of the 2024 version draft of Document 150 5. Relevant sections of the Chinese version of ASME VIII -2010 Question 1: Starting with the provisions regarding inserted fittings, the original text states that “for inserted fittings, the greater of the thickness of the fitting weld, the thickness of the shell weld, or the thickness of the head weld (whichever applies depending on the location of the fitting), together with the thickness of the reinforcement ring and the thickness of the fillet welds connecting the reinforcement ring, shall be used as the applicable value.” By “thickness of the fitting weld,” it refers literally to the weld thickness. There may be two types of welds on a fitting: Type A and Type B. There is no ambiguity regarding Type A welds, but for Type B welds, it is possible that the weld thickness is less than that of the base material. In such cases, should the weld thickness be taken as the standard? For example, the case where a red line is drawn in item 5 of the ASME standard mentioned above (in the form of a reinforcement pipe; it seems that the explanatory notes during the draft stage referred to this aspect, but it wasn’t explained clearly). If the joint has no welds, such as LWN-type flanges, does that mean there’s no need to consider the thickness of the joint welds? 2. As for the fixed-type connection, the original text states that \"for fixed-type nozzles, the larger of the nozzle thickness, the thickness of the weld on the cylindrical part or the thickness of the weld on the head (one of these values is chosen depending on the location of the nozzle), the thickness of the reinforcement ring, and the thickness of the fillet welds connecting the reinforcement ring\" should be used. In the case of a reinforcement ring, when the thickness of the nozzle varies above and below, it should be based on the thickness of the nozzle at the area where it is welded to the shell, in accordance with GB/T30583-2014. 3. Common issue: \"Cylinder weld thickness and head weld thickness.\" In the case of an access cover with an opening, whether it is of the mounted or inserted type, there are no welds on such a cover; then should the thickness of the D-weld still take into account the thickness of the access cover? It seems that the standards in this area are intended to be more precise, but there is still some ambiguity. Why not simply use the thickness of the D-weld joint to describe it, rather than using the thickness of the welds on the joint? I welcome any guidance or feedback.