Thicker flange end in ASME B16.5

[Pavis1968]

I have a question:
Have you had a situation like: to have a thicker wall thickness in flange ending?
for example, consider the 16" flange with ID equal to 16" SCH 40 piping , but need a thicker wall thickness in flange side.
the problem is coming that I have pipeline pipe which is higher grade material like API 5L X52 (SMYS is 52 ksi) but I want to connect this pipe to B16.5 flanges 16" size but SCH 60 because it is A105 (SMYS 36 ksi) , I shall use Fig 1 of ASME B16.5, (internal tapering as Fig 2 ASME B16.5 is not permitted as per Z662 Canadian code for sour service).

So the question is how to make this flange

option 1- take 16" SCH40 flange cut back reach SCH 60 and then make hub as Fig 7 ASME B16.5, the question is , "Is this approach allowed by code or not?

Option 2: take a self reinforced flange and machined it to required dimension, again the question is : "Is this approach allowed by code or not?

Sorry for long story question , just I thought may be you have had similar situation in past?

 

[saplanti]

Why do not use higher grade flange material (there is an ASTM standard for pipeline grade equivalent forging, the link is below )at the end of the pipeline. The other side can still be A105 Sch 60.

http://www.astm.org/Standards/A694.htm

Hope it helps.

Ibrahim Demir

 

[Pavis1968]

Saslanti, thanks for reply;
The reason why I did not select other high strength material (for example A694) is that this kind of material is not listed in ASMEB16.5 and so I do not have full range temperature - pressure rating, this is the reason that I have to select A105.

 

[LittleInch]

You must be using a diferent version of 16.5 to me (2009) as your figure numbers don't make sense.

For me you have two options.

1) take a 16" sch 60 flange and weld your sch 60 pipe to is and machine the inner corner of the flange at 1:4 or greater so that is matched the sch 40 flange it is bolted to with you sch 40 pipeline. As this is relatively unstressed material I cna't see why it is not allowed under the code

2) take two sch 40 flanges and then weld a sch 60 X 52 spool piece which is then machined down at the connection end to the flange to a sch 40 dimension at 1:4 or better and then weld your sch 60 A105 pipe to the sch 60 end of the spool piece.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way