Issues regarding the execution standards for elbows
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I saw a drawing where the bending radius is equal to 3 times the nominal diameter; the applicable standard is GB/T 12459. Is this appropriate? 12459 doesn’t have elbows with a nominal diameter 3 times larger, right?
There are no elbows with R=3D in 12459; elbows with =3D are available in SH/T3408 and ASME B16.5
Yes, SH/T3408 has 3 times that amount. In the power industry, there is a GD2000 manual that also mentions elbows with a diameter three times that of the pipe – namely elbow bends – but no specific implementation standards are provided
It is included in SH/T3408. .
Large-magnification elbows can be provided with drawing-based specifications, while the control of other tolerances is based on GB12549
Standard options should be used first; diagrams are generally not required
Requirements and standards set by the owner according to their needs
It depends on whether a straight section is included; if a straight section is added, it is considered a bent pipe, while if no straight section is used, it is considered an elbow. The current GB/T12459 standard is still under revision, and the new version is expected to be released soon. For now, when no straight section is used, the 3408 standard can be followed
It’s usually 1.5 times, right?:o
Yes, those without straight sections are called elbows, while those with straight sections are not elbows. Elbows are generally formed by hot pressing, whereas bent pipes are formed by bending; the processing methods differ. I’m not sure how to take this difference into account in design
A hot-bent elbow is formed through a process of heat bending and heat expansion, while a cold-bent elbow is created by cold pressing at constant diameter. There are two common types of elbow bending: one is mid-frequency heat bending, and the other is cold bending