Developing manufactured flanges from near net shape

[hubby89]

My boss has asked me to look into a procedure to produce manufactured flanges from near net shape, bar stock, or existing flanges. We want to be able to to create a method for quickly manufactured flanges when needed quickly.
If you take an already manufactured flange and machine it into a different size, does it have to meet any standards? Does anyone have any suggestions on how to accomplish this. or just some help in general about the subject.

 

[hubby89]

moltenmetal,
I am trying to find full-sized weld neck flanges forged into shape without having the bore forged through too. I have not found a vendor yet. Have you machined your own flanges? If so, how have accomplished this? What standards are you using?
We quoted a high price job and we gave a guaranteed ship date, however the lead time to receive the flanges was later then the ship date, so we need a way to obtain/machine flanges so this does not occur again.

 

[moltenmetal]

hubby89: exactly the same problem we've had in past- VERY frustrating and costly!

I am NOT an ASME expert so take what I say with a grain of salt. It is my understanding that under B31.3 you are permitted to make certain pressure-boundary components from bar provided that you do the required soundness testing on the raw material. If I understand correctly, that's UT prior to machining, and material strength tests in both the axial and radial directions. The process is similar to what you'd need to do to make an ASME VIII appendix II hubbed flange from plate. This will permit you to make a flange which is safely equivalent to a B16.5 flange in terms of function- but it will not bear the B16.5 markings because it did not start out as a forging.

A code expert here may be able to quote you chapter and verse on this- and correct any errors I may have made in what I said.

 

[strokersix]

Flexon is a source for roller chain sprockets with hubs often fully machined from near net forgings. I envision your flange needs might be similar. Perhaps they would be interested in providing forged blanks.

http://web.flexon.de/index.php?id=748

 

[ME231]

I just came across this thread while researching for answers to a question I had of my own.
How can bar/rod material be used in manufacturing/machining flanges (integral to the shell) for ASME code vessels.
We use Code cases 2155/2156 for justifying the shell and head, but are having problems justifying the flange this way.
Could anyone please point me to some obscure code case/ interpretation that allows this?
Please share your experiences/knowledge.
Thanks much in advance.
SP

 

[cncek]

I am not sure this will help, but when I used to do this work on pressure vessel flanges for a local company. I near netted the flanges on a flame table from A572 plate and machined them on a CNC machine with a third axis (turret had live head capabilities which we used to do the hole drilling work on the lathe). We used this method extensively to produce parts pretty quick - I could have a flange on your dest in about 15 minutes... I am not sure how thick a flange you need but I would seriously suggest you find a machiner in your area with flame table capabilities. This is as close as you will come to near net from traditional machining. If you can used ductile iron for your flanges then I would suggest that you look into a material known as Dura-Bar (Countinous Cast Ductile iron bars) - you can find them by searching for Dura-Bar on Google. This material will produce the fastest machined flanges of any standard bar-stock.

Hope this can be some help to you...

Sincerely,

Eric K.
"Strive for perfection in everything you do. Take the best that exists and make it better. When it does not exist, design it." Sir Henry Royce