Hi! everyone,

Regarding above subject, I'm wondering what the difference between Welding tee and Extruded welding tee is.
when we input tee type, we must choose one of two type. however i'm not sure witch type shall be selected.
anybody know that, please let me know.

Regards,

Good grief.

A welding tee is a component welded into the piping system via three welds. An extruded tee is usually formed from pipe of heavier wall than would be needed for pressure alone, by pulling a ball like former through the (red hot) wall of the pipe, then machining back.

You should read your pipe specs to find out what type of tee to define in Caesar. In very large bore applications, you may need to check out the manufacturing method.

Thanks for reply.

Regarding SIF value between Welding tee and Extruded tee, ASME B31.3 2008 Edition appendix D shows the difference SIF value. In general, Tee is made as above explanation even though Welding Tee described in ASME b31.3 Appendix D. That is to say, all of configuration and thickness are same. However, difference accordance with ASME B31.3 Appendix D are as follows.

1. Regarding Extruded tee, crotch(Tc) should be less than 1.5T and
2. Regarding Welding tee, there are no limitation in ASME B31.3.

According to I have confirmed verification of both welding and extruded tee type to fitting vendor, they don't specify both welding tee and extruded tee separately as per ASME B31.3 Appendix D, and they manufacture tee accordance with ASME B16.9. And also the crotch(Tc) thickness is 100% of T by default if 150% and larger is not required by client.
In this case, Tc<1.5T, which type shall be seleted to get SIF correctly between Welding tee and Extruded tee when I input Tee Type in CAESAR II?
I hope COADE staff will give me solution.

Best Regards,

Anybody no reply here?

Please give me your good experience.

Best Regards,

Go to the attached link. Maybe it can be useful to understand the difference between extruded and welding tee

http://www.t-drill.fi/files/ASTM_F_2014_Collaring.pdf

Regards

Thank you very much for information.

However, it seems there is mismatch answer compare to my question in your reply regretfully.

Now what I'm concerning is how to apply SIF value either Welding Tee or Extruded Tee in CAESAR Input in case of Tc<1.5T.

Please let me know if you have correct information.

Best Regards,

Is there anybody who can judge for this topic COADE staff especially?

Welding tees: B31.3 Appendix D sets the flexibility characteristic (h) to 3.1Tbar/r2 if Tc<1.5Tbar and 4.4Tbar/r2 if Tc>=1.5Tbar. There is also a check for rx. See Note (8). If you specify acceptable values for Tc and rx in CAESAR II input, the program will use the larger h.
Extruded welding tees: B31.3 Appendix D only provides these SIFs for Tc<1.5Tbar.

It looks to me that Code gives you SIF values for Tc<1.5Tbar for both of these intersections.

Dear Dave Diehl,

Thanks to advise me.
You mean is that welding tee is always able to be used regardless of cortch thickness(Tc), Tc>=1.5Tbar or Tc<1.5Tbar. Is it right?
The reason why I try to confirm Crotch thickness(Tc) to you is changed code requirement for welding tee as follows;

1)ASME B31.3 1996 Edition
- Tc>=1.5Tbar
2)ASME B31.3 2004 Edition
- No Limitation. However, Tc>=1.5Tbar was moved to Note 11(If rx>=1/8Db and Tc>=1.5Tbar, a flexibility characteristic of 4.4Tbar/r2 may be used)

Please give me your opinion one more.

Best Regards,

I believe you will find that the 1996 Edition had a note (I guess Note 11) that cautioned the Code user that the welding tee SIF should be higher (by making h lower) if that crotch thickness was too small.
The change that you see in the 2004 Edition simply switches the two statements - placing the more conservative SIF in the Table and putting the reduced SIF in Note 11.
The treatment is the same. It's just human nature to gloss over the notes.

Dear Dave Diehl,

Thanks for advise me

Sincerely Yours,

As Mr. D.H. Seok query,

I have another doubt of difference between buttweld tee and welding tee. Where it must be used for specifying tee. For example, a 4" elbow ASTM A 234 WPB Seamless, do we have to mention buttweld tee or welding tee. From my concern it must be buttweld tee. The doubt arised due to confusion with my team. Please correct me if i am wrong.

Are you refering to the "Type" parameter in the CAESAR II "SIF's & Tees" window?
This list of 17 items includes tees and joints. Tees are the intersection of three pipe elements (e.g. welding tee, sweepolet, etc.) and joints mark the junction of two pipes (e.g. butt weld, socket weld, threaded joint, etc.).

Our list includes these two items - "3 - Welding" and "7 - Butt Weld". Number Three is an intersection and Number Seven is a simple joining of two pipes.

Markl's work (and therefore, the B31 Appendix D work) uses the girth butt weld as the base line for the SIF calculations. For the B31 Codes, a butt weld has an SIF = 1. Therefore, we need not indicate the position of butt welds.

Dear Dave,

Yes, i am refering to the "Type" parameter in the CAESAR II "SIF's & Tees" window.

From your explanation, what i infer is that, for normal tee (intersection of three pipe elements) welding must be specified (i.e.) item no. 3.

Then, why the option of buttweld is listed in the "SIF's & Tees" window. As u have said and as per B31 code, buttweld has an sif=1.

Also the confusion has come due to the reason is that, even though the connection of tee is welding, but the type of weld connection is the buttweld. So this makes to blink which must be selected.

Thanks for ur reply.

Not all codes have an SIF=1 for girth butt welds.

For B31.3, you can ignore the SIF at the connections between the welding tee and the attached component and code directly to the intersection of the main and branch centerlines and specify your tee (3) there.

I am facing a problem with the tees and SIF.
ASME B31.3 edition 2010 table D300 lists two fittings one is welding tee in accordance with ASME B16.9 and other is extruded welding tee with Tc < 1.5 T. Now manufacturers of tees (supposed to manufacture tees as per ASME B16.9) do not provide the tees with Tc < 1.5 T. It is stated by one contractor that he has confirmed from manufacturers and Tc is 25 to 40 percent more than T'' not 150% of T.

In this case while using ASME B16.9 tees, should we consider SIF for extruded tee instead of B16.9 tee?

Please note that as per contractor, if he insists manufacturer to produce tee with 150% T then they take it as special order and ask for more delivery time and of course impact on schedule and cost of the project.
Please help!

The code interpretation 1-7 dated April 11-1980 opines like this: "It is the opinion of the Committee that extruded ANSI B16.9 welding tees with a crotch radius less than 12.5% of the branch diameter may use flexibility characteristics and stress intensification factors for an extruded welding tee, provided the crotch thickness is less than 150% of the nominal wall thickness of the header pipe. If the crotch thickness is greater than 150% of the nominal header wall, or the ANSI B16.9 tee is fabricated by methods other than extrusion, the designer has the responsibility to determine the proper flexibility characteristics and stress intensification factors."

So we can use the extruded tee SIF instead of welded tee!
Any other opinion?

A few years ago,B31.3 changed Appx. D for the welding tee. The default flexibility factor was 4.4*T-bar/r-sub-2 with a note stating that if the crotch thickness was less than 1.5*T-bar, then use the more conservative h=3.1*T-bar/r-sub-2.
Now, the more conservative h is default and the thicker T-bar is the exception.
In my opinion, you can use the welding tee h with that 3.1 multiplier.

Shahid,
It is surprising to note that the tee manufacturers don't provide the crotch thickness as 150% of nominal thickness. I read ASME B16.9. There is no such requirement as 150%. But it is stated that some portions may be thicker than nominal thickness.
So if ASME B16.9 does not state 150% as a requirement, manufacturers can make tees having thickness of crotch less than 150% and still comply with B16.9.

But for stress analysis, we normally take type 3 in the CAESAR II for B16.9 branch connections. Do we need to change this practice?

That's a odd thing about Appx. D. B16.9 does not have a direct relationship with geometry. To me, B16.9 just means the tee won't burst when pressurized within the stated limits.
As I understand it, there was a time when manufacturers generally followed the 150% thickness but no longer. That's why B31.3 now defaults to the more conservative h.

And now B31.3 Edition 2010 gives note (8):If rx ≥ 1⁄8 Db and Tc ≥ 1.5T , a flexibility characteristic of 4.4 T /r2 may be used.
So these two points changed positions. Thanks for your post!