Regarding the issue of welding parameters in WPS where two PQRs are used for coverage
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Question! In actual WPS, there is pipe insertion welding (Type D weld joint); often, since it is necessary to account for both the thickness of the pipe and that of the vessel wall, two PQR values are required for the same welding method in order to cover these aspects. The standard understanding is that it can be used when the important factors, supplementary factors, as well as conditions such as shocks and heat treatment are the same. However, when comparing actual weld qualification PQRs, the welding current, voltage, and maximum linear energy parameters for thick plates’ PQRs are higher than those of thin plates. In the example used by the Chemical Equipment Association in compiling the \"Guidelines for the Evaluation of Welding Processes for Pressure Vessels,\" the maximum current, voltage, and linear energy parameters were determined based on the WPS formulated for thick plates; these values exceeded the maximum linear energy allowed for thin plates. My question is: since the linear energy has already exceeded that of the thin plate’s PQR value, and according to Table 6 of standard 47015, an increased linear energy value is used as a supplementary factor (requiring additional impact toughness tests), it seems that the purpose of this adjustment conflicts with the standards ?
Your question isn’t expressed clearly enough; the details still need to be discussed. What you need to focus on is whether the key factors and additional factors for thin plate welding assessments and thick plate welding assessments cover those that are important during actual welding, rather than requiring these two sets of assessment factors to overlap or be exactly the same.
Thank you, it’s you again! The two weld assessments do not overlap each other. Could you help me take a look at this situation? PQR-01: SMAW, 120-140A, 20-24V; maximum wire energy of 16 kj/cm. PQR-02: SMAW, 140-170A, 22-26V; maximum wire energy of 20 kj/cm. The WPS should use PQR-01 and PQR-02 with SMAW settings of 140-170A, 22-26V, and a maximum wire energy of 19 kj/cm. All other important factors remain the same as before. The maximum linear energy of WPS here exceeds that of PQR-01; can this be understood as a change in the supplementary factor? My question is about this example, hehe
In such cases, the WPS line energy I calculate does not exceed the smaller value. Otherwise, what meaning does that small wire energy weld assessment have here? Following the example given by the original poster, if in your WPS setup the current and voltage remain at PQR-02 levels, it shouldn’t be difficult to meet the requirement of 16 kJ/cm by increasing the welding speed, or by reducing the current and voltage slightly
This definitely won’t work. This additional factor of wire energy has exceeded the acceptable value specified in PQR01.
Yes, indeed. I’m actually following the smaller one right now as well.
Okay. I raised this question after seeing it in the product examples of the book \"Guidelines for Welding Inspection\". I’d like everyone to help me clarify some doubts. Thank you for your help.
It’s too thin; increase the thickness. Otherwise, follow the standard and make additional test pieces, performing only impact tests