I have designed a shell of 406.4 mm and there is no weld neck flange having nominal bore of that dimension.

The closest I can find is flange dimension if nominal bore 387.4 mm, I donot want to machine the flange as it will reduce the strength.

Please advice me on it

Here is the complete information

406.4 mm (16") is the inside diameter of the shell and the wallthickness is 10 mm.

Design conditon and flange rating
MAWP = 10 bar @ 150 (degree) celcius
Flange material = 2.2 austic stainless steel (316L)
Flange rating 150 lb
Flange type - weld neck flange.



Rem:Every thought counts

Materialboy,

You have two options;

1. Change the shell to 16" NB (ie 406 mm OD) and use standard flange

2. Use a custom designed flange with 406 mm ID if can not change shell dia.

Regards

Thanks Sanjeev :)

I totally agree with your point sanjeev and I will be using option 2 (Long weld neck flanges).
http://www.red-bag.com/engintools/flange_dimension.php

Long weld neck flange is butt welded to shell at an angle of 37.5 (degree) and outside diameter of weld neck is ‘MACHINED at an angle of 14 degree’ for smooth exterior.
( Wish I could attach the dxf format to explain more)

Will I need to recheck flange to Appendix 2 (ASME) as I am machining the flange for smooth exterior and if I do how will I work out thickness??

PLease avice me and let meknow if more information is required

From your mail I understand that to meet the welding edges you are going to machine LWN flange from inside at an angle of 37.5 Deg and from outside at an angle of 14 degree.

Why can't you use a shell with 16"NB dia, even by machining the flange on the hub section, your ID at the flange top shall be less than the shell dia.

If want to modify a flange, yes you need to verify the flange design as per appendix 2

Not able to understand what you mean by "how will I work out thickness". It shall be as per appendix 2.

Regards