For large-diameter flanges used as equipment flanges, how is the straight edge length determined?
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In the standard HG/T20615, for large-diameter flanges used as equipment flanges, how is the straight edge length determined? It seems there are no straight edges in the standard?
It’s simply a matter of determining how thick the portion with material remaining is after the straight edge section is inserted into the large flange
Referring to 150, generally 1.5 times the thickness of the straight edge portion is taken
Is there a problem with no straight edges? In d) of Figure 7-1 (continued) in GB/T150.3-2011, there is no straight edge section. If such flanged equipment is connected to a head, a section of cylinder should be added.
Can the equipment flange be connected directly to the head, without an intermediate cylinder section? Is that okay? Please give me some advice!
It is best to add a tube section with a length greater than the stress attenuation length, to avoid overly complex stress conditions on the circumferential seam.
5.11 Flanged convex heads in GB/T150.3-2011 – I’m not sure if this is what you were looking for.
I’ve seen in some other companies that, when using large-diameter pipe flanges as equipment flanges, they are welded directly to the head, without adding any tube sections. What’s going on here? Hope the expert can clarify this?
It is necessary to comprehensively consider various factors such as operating parameters, material, medium, and type of corrosion in order to determine whether to use a short section. However, from a stress perspective, a longer joint is better.
I’ve never encountered this situation; I learned from it. For the flanges on equipment, the equipment’s own flange standards are generally preferred. In previous experiences with connections between equipment flanges and end caps, for butt-welded types, a sleeve section must definitely be added; otherwise, the welds would be too close together. I just checked the specifications for long-neck butt-weld flanges; the standard requires that the length of the tube section be no less than the square root of (DNxδ). I’m not sure if this can be used as a reference.