Is it allowed to cut and modify 45-degree or 90-degree elbows into elbows of any angle during piping installation?
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Is it allowed to cut and modify 45-degree or 90-degree elbows into elbows of any angle during piping installation? The screenshot shows a fitting with a DN50 diameter; the center distance between the pipe ends is 70 mm. If two 45-degree elbows are used, the length of the short pipe segment in between is 29 mm, which does not meet the requirement specified in the \"Code for Design of Industrial Metal Piping\", namely that the distance between two welds on pipes with a diameter of DN50 or larger should be greater than 100 mm. The minimum connection length for 90-degree and 45-degree angled joints is also greater than 70 mm. So the only option is to consider cutting the elbow at any desired angle, but it’s not clear whether the regulations allow this
Consider various factors? Losses, stress, specifications, and so on
1. There is no prohibition on cutting 45-degree or 90-degree elbows into elbows of any other angle during piping installation. 2. Problems will arise: the dimensions of the cut ports vary greatly, making it difficult to align them properly. 3. As for the spacing between the two welds, I think the standards set in China are unreasonable; there are always situations where it’s impossible to comply with those standards. Standard conditions should be written as \"suitable\" rather than using words like \"must\". In summary, it is more appropriate for you to use 2 elbows connected together.
Elbows can be cut; 45-degree elbows that cannot be welded on-site are also created by cutting 90-degree elbows. As for the regulations requiring that the weld gap be no less than 100 mm for diameters equal to or less than DN100, and no less than 150 mm for diameters equal to or greater than 150 mm, some believe this is based on considerations of ease of construction and the impact zone caused by welding. Welding problems can generally be overcome on-site, and it is argued that the impact zone isn’t that significant; in situations where there is really no other choice, a gap of several dozen millimeters is acceptable
The regulations do not state that elbow cutting is prohibited; in practice, many elbows with irregular angles are cut at 90 degrees or 45 degrees
For some equipment, the piping locations may have such arbitrary angles; the design should try to avoid such angles, and explanations should be provided for any designs that include such angles
Elbows can be cut into elbows at any angle using 45-degree or 90-degree bends, which are commonly used in pipeline connections.
This post was last edited by yujwlhh on 2021-7-20 09:36. Strictly speaking, it shouldn’t be possible. It is still more appropriate to design the aforementioned piping with 2 elbows; the installation specifications also state that, with the exception of standardized fittings, the requirements for minimum dimensions can be relaxed. This problem is often encountered in pump piping.
During normal construction, 90/45 degree elbows are often cut and polished to achieve the desired shape. Of course, it is still necessary to try to avoid it during design.