different schedule between run and branch pipe for tee? is it possible?

[Zul78289]

Dear all,

pls help me with this case. is it okay to have a tee with this specification (tie-in case) :
1. run pipe size 16" (existing line) with Sch XS
2. branch pipe size 14" (new line) with Sch 40
3. design temperature 360 C (Steam MP)
4. design pressure 18 bar
5. pressure rating class #300

thank you for helping me.

regards,

 

[davefitz]

I canot confirm this specific case, but the ratio of wall thickness to OD { t/D) is not a fixed ratio for the same pipe schedules but differnt diamters , so it is feasible that different schedules can meet the same design T + P , as D varies

"...when logic, and proportion, have fallen, sloppy dead..." Grace Slick

 

[XL83NL]

I could confirm the specific case (provided all info is given, such as design code - which is missing), but I wont.
Nevertheless, the calculation to verify if the wallthicknesses meet the code requirements are easy and should be done by you.
You mentioned you have a tee, but also mentioned tie-in case. Is this a pipie-2-pipe branch, or a B16.9 tee?

 

[DekDee]

I agree 100% with XL83NL.
Are you a Piping Engineer ?
If so you should not be posting questions that you should be able to answer yourself.
If you are not - where is your Piping / Design Engineer ?

 

[GD2]

Zul78289,

[ul]
[li]First determine the construction code.[/li]
[li]Do a quick thickness calculation for the branch pipe as per the equation given in the code.[/li]
[li]If it meets, then it is acceptable.[/li]
[li]Different schedule welding is allowed under codes. Many codes provides the joint configuraion.[/li]
[li][/li]
[/ul]

GDD
Canada

 

[KevinNZ]

If the DN600 (16") line is XS (12.7mm) then design with an XS reducing tee DN600-350. You can then tapper the DN350 (14") XS 12.7mm branch to 11.13mm (SCh40) and weld to the SCH40 pipe.

You still need to complete the full pressure and other stress design of the modified piping. This may require and even thicker tee.