30"x30"x45 Degree TEE - Crygenic (-170C) +Posible to forge?

[Hansito]

L&G:
We have CRYOGENIC SERVICE (-170 C) in our LNG project. The proper client Piping Class specifies Tees for branching on that service, I mean THEY ONLY USE FORGED FITTINGS for this service, not pipe to pipe branches. Even for different diameters, Reducing Tees are specified. However, some of these lines require a single plane 45 degrees branches .It is the case of the Flare lines connections, they can't be at a 90 degree angle.

My concern is: if for all other cases they avoid pipe to pipe branches, I suppose to minimize the Stress intensification factors, it looks not congruent using reinforced piping branches for the 45 degree cases.

To be more specific our worst case data are:

8"x8"x 45 Degrees and 30"x30"x 45 Degrees - Cryogenic service (-170 C) - Flare system.

It seems too much for a reinforcing branch and we are not sure about suggesting the fabrication of a special fitting.


Please, if someone has faced a similar situation or have any comment or suggestion about it, let me know.


Regards,

Hansito

 

[unclesyd]

If I read your OP correctly, have you looked at forged laterals, "y shaped"?
The 8"x8" shouldn't be a problem. The 30"x30" will be a little more difficult and might have a long delivery time.


Can I assume that your material is Stainless Steel?

What is the Sch for the pipe/fitting?

 

[carthago]

QUESTIONS:
1/- what is the reason of using tees with 45 degree for flare lines on LNG plants?

2/- Which formula is used to derive the SIF (stress intensification factor)for tees with 45 degrees ?
----------------

It is known that tees with 45 degrees require more compensation area for internal area

Tees with 45 degree will have a higer SIF than normall tees

 

[LSThill]

Hansito (Industrial)

http://www.wfi-intl.com/

WFI's office and plant are located at 4407 Haygood Street, Houston Texas 77022. Our professional staff can be reached 24 hours a day, 7 days a week at 713-695-3633 to assist you.




L S THILL

 

[Hansito]

Dear Coleagues,
Sorry, I've been out of office recently.
Thank you very much for your help. I appreciated them all.

Unclysyd:
You're right the material is SS tp 304. Sch 10 for diam 30" and Sch 10s for 8". They use EFW, reggarding to pipe, just for information. You are also right about the diameters, the 30" is a more difficult concern, yes someone in the project mention the laterals for 8 inch, but not have been decided yet.

Carthago:
The reason for 45, as a process engineer told me is to be sure that the flow during the discharge will have a dominant direction and way towards the Flare Stack. I'm on the piping department so I can't do much more but accept it.

Reggarding to the formula, as far as I know, there is nothing written down on the codes (ASME in this case) about it.

I agree with you a 45 degree needs more compensation area, but my main concern is the intensification factor at the sharp edges (if it was pipe to pipe branch) at cryogenic temperature.

LsThill:
Thanks for the WFI direction. I've send them an web page post ip about a month ago with no answer till now. I'll use the phone number you are giving me this time.

Regards,
Hansito