Issues with the welding joint coefficient?
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This post was last edited by kareale88 on 2019-4-22 at 16:12. bg4.png features one cylinder; the cylinder body is made of seamless steel pipe with a diameter of 426, and the end caps have no welds. The entire shell consists of only two weld seams (the welds where the cylinder body meets the end caps). It is a category II vessel, requiring 20% X-ray inspection. The welding joint factor indicated in the drawings is 1/0.85 – do you think this is appropriate?
If marked in this way, \"longitudinal seam/circumferential seam\" should be added after the weld joint coefficient
With such a small diameter, use 100% RT directly; take 1.0
Cost considerations must be taken into account, as well as the difference between grade II compliance and grade III compliance.
426 diameter, can the cost differ a bit? Grade II compliance has been achieved, and the quality has also improved.
Since seamless pipes have no longitudinal seams, whether it is a 20% RT or 100% RT test for the circumferential seams, the welding joint factor is usually determined by the longitudinal seams; in practice, this value is taken as 1.0. However, some inspectors or supervisors insist on using a 20% value, requiring explanations from the designers. It’s fine when it’s something that can be understood; but when it’s not understandable, it becomes much more troublesome. Just go 100% RT and avoid all this hassle.
I think it’s fine for companies with good welding skills； If the quality of welding techniques is poor, the pass rate for grade II is very low; carrying out repairs in such cases basically results in no profit. As for steam distribution cylinders, they are usually made of carbon steel. For these type B seams (which are not specified in the technical specifications), the required proportion is 20% or more; the technical specifications state 1.0/1.0 ； It varies by company
Sometimes, with welders of poor skill, it’s quite difficult to achieve grade II 100% of the time.
Are there inspection ports on the device? Or is there a pipe fitting that can also serve as an inspection port?
If it’s not achievable, then don’t bid for it. The league can’t always cater to the teams at the bottom of the standings
Devices such as cylinder dividers do not require 100% non-destructive testing.