Welding procedure qualification
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①The product technical requirements do not specify the need for impact testing; however, since a weld evaluation with impact testing is being used, the maximum value I can adopt is 2T as specified in Table 7. What is mentioned later in this diagram is still either 2T and 16, or T/2. ②One more question: the weld evaluation includes an impact test report, but it was conducted at room temperature. Is this a routine test that must be carried out? (In other words, if there are no requirements for the product, then it should be processed at room temperature; if there are requirements, it should be processed at the specified temperature. Is that correct?) So, the thickness covered by room-temperature impact testing is based on 2T, rather than what’s indicated in the diagram?
1. If the product’s technical requirements do not specify the need for impact testing, but impact testing is included in the actual welding process evaluation, then the maximum thickness covered is treated as 2T. As for the explanation regarding \"the minimum of 2T and 16, or T/2\" that appears behind the diagram you mentioned, it is necessary to refer to the specific welding specifications or standards to determine how to apply this principle. 2. Regarding impact testing, if the welding assessment includes an impact test report at room temperature, this is generally not a required test, unless explicitly specified in the product’s technical requirements. For products with no special requirements, conducting impact tests at room temperature is generally done to ensure welding quality. If the product specifies a particular testing temperature, the impact test must be conducted at that specified temperature. The covering thickness for room-temperature impact is usually considered to be 2T. .
My understanding is as follows: 1. When the material requires impact testing, the weld evaluation should also include an impact test; in this case, the maximum coverage area for welding is 2T, while the minimum coverage varies – when the thickness is less than 6mm, the minimum coverage is T/2； When the thickness is greater than 6 mm, the minimum value is the smaller of T and 16; for example, when the thickness is 10 mm, the minimum value is 10, and when the thickness is 20 mm, the minimum value is 16 mm. 2. Generally, it is based on the standards for the materials; if the material standards require impact testing, then such testing must be carried out ； For the thickness range you mentioned, only the maximum value is specified, which is 2T; the minimum value is determined according to what was stated above.
Clause 6.1.5.2 of standard NB47014-2023 stipulates that when a welding procedure qualification with impact testing is applied to weldments that do not require impact testing, the provisions of Table 6 or Table 7 shall still be followed.
Regarding the reply to the first question, I personally agree with the opinion from the second floor； Regarding the second question, it can be divided into two points: 1) Whether room temperature impact testing is a routine requirement for testing actually depends on the first question, namely determining whether impact testing is necessary ； 2) Regarding the selection of the impact temperature, this is generally determined in accordance with the impact temperature specified in the material standards, while also taking into account design requirements (the minimum usage temperature of the material is already taken into consideration during material selection). For example, for Q345R material, the impact temperature required by the material standards is 0 degrees, but this material can also be used in environments with a minimum temperature of -20 degrees; therefore, when evaluating Q345R, it is advisable to choose an impact temperature of -20 degrees. For more details, refer to clause 6.4.1.7.3 in NB/T 47014-2023. The above is for reference~~~