The issue of using batches instead of individual test plates for product welding tests
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Could someone explain the provision on page P38, item 3 of the Standards, which allows the use of batch-based welding test plates in place of individual test plates? If the manufacturer can provide test data for welding test plates of 30 consecutive units made from the same material grade, using the same welding process and following the same heat treatment specifications, then by \"same welding process\" is it referring to the welding process qualification? For example, when it comes to producing glass-lined equipment, I already have welding procedure qualification data for temperatures above the upper transition temperature; the thickness is 22 mm, the material is Q235-B, and the range covered is 5–24.2. So when I start production, does the inner cylinder’s thickness just need to be within the 5–24 range? If 2 units are added to reach 30 in total, is it then unnecessary to produce trial boards? Thank you very much
However, the boiler inspection agency requires us to produce 30 units using inner tubes with a thickness of 16, on the grounds that a plate with S=16 has a coverage range of 5 to 17.6, which is sufficient to cover our existing products. I don’t think this makes any sense; they seem to be focusing on the welding process rather than process evaluation. I would appreciate some guidance from those who are more experienced. In any case, whether the thickness is 12 or 16, the same welding process evaluation should be used. [Last edited by kly907 on 2008-2-21 at 15:56]
Replacing individual test pieces with batches means that, within the scope covered by the same weld evaluation, once 30 consecutive batches of product test pieces using the identical welding/process heating procedures have passed the tests, they can be registered with the boiler supervision agency to allow replacement of individual test pieces with batches
The same welding process should refer to those welding processes that can be covered by the same welding process qualification, allowing for 30 consecutive units to be welded, with the note that this should be within a period of six months.
The welding process is not the welding procedure qualification; the colleagues at the inspection institute are right – the welding process refers to the entire set of procedural steps and technical specifications involved in the welding process. The content includes: welding methods, pre-welding preparation and processing, assembly, welding materials, welding equipment, welding sequence, welding operations, welding process parameters, and post-welding treatment. Welding procedure qualification is the testing process and evaluation of results carried out to verify the correctness of the proposed welding procedure for the weldment.
I think it should be understood as welding procedure qualification
It can be said that the welding process is also acceptable, but there is an additional requirement regarding tolerance limits: \"The important welding factors and additional important factors must not exceed the acceptable range.\" Can it be understood that the welding procedure qualification used as a basis is the same in such cases? To be more specific, for plate thicknesses of S=8 and S=12, different welding processes are used, but the important welding factors and additional important factors remain unchanged; thus, the welding procedure qualification used as a basis is the same. Therefore, I can combine products that meet these conditions – as long as there are 30 of them in total – and batch them together, right?
Do everyone think this topic isn’t good? Not very interested? A definite answer would be great too! Urgent! Please help, moderators!
The original poster’s understanding is correct. Back then, I discussed this with the colleagues at the boiler inspection agency using the criterion that \"the important welding factors and the additional important factors must not exceed the acceptable range for evaluation.\"
It is necessary to determine whether to redo the process evaluation based on the material thickness range specified in JB4708!
The same welding process includes the key factors and additional factors of welding, which must remain constant. Materials, welding methods, welding materials, single-pass welding or multi-pass welding, etc