Seeking advice on pipeline welding issues
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I would like to ask the experts: can two pipes with significantly different wall thicknesses be joined together by grooving and welding? Are there any relevant standards that limit the wall thickness of pipes? Thank you!
Experts, please help answer: Can pipes with a wall thickness of 17 mm and 10 mm be welded using grooved joints?
For pipes with the same outer diameter but different wall thicknesses, it is somewhat difficult to carry out welding by preparing bevels! Imagine, how can this groove be machined? Outer groove —— ? Inner groove – the pipe diameter is too small to machine it ； When the pipe diameter is large enough, it can be machined, but it is difficult to control the groove angle. For reference!
When welding pipes with unequal thicknesses, the thicker end must be thinned, with a slope ratio of not less than 1:3; otherwise, stress concentration will be too high. . .
See Appendix H of the Code for Design of Industrial Metal Piping GB50316
Pipes with wall thicknesses of 10 mm and 17 mm can barely be welded together. Pipes with such thick walls should have a nominal diameter of DN600 or more, but the wall thickness isn’t the deciding factor; the outer diameter of the pipe also matters. It’s simple logic – if there’s a large difference in the outer diameters of the two pipes, it’s impossible to weld them together. Therefore, it’s necessary to consider how many millimeters of cross-sectional area the pipes have in order to determine whether they can be welded together
The poster should make things clear: first, the nominal diameter must be the same; secondly, it is necessary to specify what the diameter of the pipe is. In principle, such welding should be avoided as much as possible, but in practice it is possible to do so. In many installation sites, diagonal jointing of the pipe ends is used to adjust for height discrepancies, and the principle behind this is similar. Therefore, a beveled joint is feasible, provided that the pipeline in question is not a critical process pipeline, as otherwise there could be potential safety hazards.
It is related to the pressure in your pipeline; there are requirements regarding the amount of misalignment!
What are pipe applications? For pipes that are not critical, grooved welding can be used.
Please refer to GB50235-97 for pipe butt joint methods
Try to avoid welding in this way! The outer diameter of the pipes must be the same! It’s a non-critical material pipeline; use bevel welding.
According to GB/T50235, the misalignment amount should not exceed 10% and should not be greater than 2 mm. For this pipe, the stress was not taken into account; therefore, the pipe was replaced with one having the same wall thickness. Thank you all for participating. The scores for today have been assigned, and those who didn’t receive a score are sorry about that
1 First, it is necessary to verify whether the wall thickness of tubes with thin walls meets the requirements of the operational conditions (based on design pressure, temperature, corrosion margin, etc.)； 2 Grooving can be used for welding; for details, refer to GB50236-98 (Code for Construction and Acceptance of Welded Works of Field Equipment and Pipelines).