Split Flange made from a forging?

[liko25]

Are there specific material requirements for split flanges? I would like to take a forged A-105 carbon steel hubbed flange to make it as a loose backing ring split flange, but I'm not sure if the internal residual stresses will cause the ring to warp after it is cut. Are there any specific material or heat treatment requirements for split rings? For reference, this will have an OD of ~45" and ID of ~36". Thanks for any insight!

 

[liko25]

Also, I know that you can normalize A-105. Will this eliminate the internal stresses? Is normalized A-105N material allowed for a flange designed per ASME BPVC VIII-1 Appendix 2?

 

[SnTMan]

liko25, 1) "Is normalized A-105N material allowed for a flange designed per ASME BPVC VIII-1 Appendix 2?"

No, but SA-105 is allowed. It may required to be normalized, or not, depending. Please read the Code.

2) Why not just make the thing from plate?

Regards,

Mike



The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[AB53Mech]

liko25,
How much the ring thickness?

 

[CuMo]

No problem using forged rings as backing rings.
We use split forged backing rings for floating tubesheets and have never had a problem. ASTM A105/ ASME SA105 (Usually dual certified).
To my knowledge the rings are first rolled to shape, machined and then cut split in two halves.

 

[liko25]

Mike, I am trying to limit my flange thickness, so I was going for a forged flange with a hub to add some rigidity. The hub also allows for some extra real estate to attach some connection lugs that we'll need to weld to it.

AB53Mech, the ring thickness right now is at 2.5 inches with a hub length of 3.5 inches.

CuMo, yes that's exactly the process I was planning to have done for this flange.

From what I've read in the code and the ASTM material spec, heat treatment (annealing, normalization, tempering) is not mandatory for flanges with a thickness less than 3 inches. However, I was inclined to specify normalization if it helps to minimize the internal stresses and avoid any warping or spring-back of the material after it's cut.

 

[SnTMan]

liko25, hub flanges are machined from ring forgings all the time. I doubt you'll have to worry about distortion from residual stresses in the forging, but you might from welding.

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[r6155]

Split ring don´t need a hub.

Regards