Barred Tees Design

[kat6787]

I am currently working on a barred tee design for a manifold piping system. The tee was originally designed with only one bar, and a concern was brought up that it should have a minimum of 2. I looked through ASME B16.9, but it didn't mention the required number of bars. Is there a standard as to how many bars are required based on the size of the tee?

TEE INFORMATION
Size: 6.625" OD x 6.625" OD x 1.042" WT
Material: ASTM A694 Gr. F65
Use: Subsea Manifold piping system

Many thanks in advance.

Cheers,
Kat

 

[JohnBreen]

http://roc-master.en.alibaba.com/offerdetail/51969019/Sell_Barred_Tee/showimg.html

thread177-153284

thread469-159827

thread124-51069

 

[kat6787]

Thanks for the thread links. I had found 2 of them when I searched before posting my questions. Those threads give a lot of good information, but don't cover how to determine how many bars are required in a barred tee. Is there a code that covers that aspect of the design, or is that more of a project specific choice that must be qualified as appropraite with analysis.

 

[JohnBreen]

Hi kat6787,

It is not covered by a Code. The Codes generally only address structural integrity and internal pressure. The bars are purely a function of operation and what is available from the manufacturers. The makers of barred Tees consider the ID of the run pipe and simply try to provide the "bridging effect" required to pass the pig along its merry wy with little or no drama. As long as there are sufficient bars to prevent the pig from getting hung up at the Tee, it is OK. I guess you have to consider the physical characteristics (size, shape, appurtenances, etc.) of the various pigs that might pass through the system.

Regards, John.

 

[BigInch]

Depends on the smallest sphere or bullet you might have entering the line from any smaller diameter piping upstream. If any upstream piping is less than 1/n * D, then require 1/(n+1) bars, etc.

BigInch-born in the trenches.

http://virtualpipeline.spaces.msn.com

 

[dcasto]

I've used rebar. On a 3" 2 @ 1/4". On 4" 2 @ 3/8" on 6" 3 @ 3/8" on 8" 4 @ 1/2", and on.

 

[SJones]

Are you designing the tee for manufacture or for purchase? If the latter, ask your listed suppliers to see GA drawings for any tees that they may have supplied in accordance with Shell DEP 31.40.20.31-Gen. From these you'll get a robust, working design.

Steve Jones
Materials & Corrosion Engineer

http://www.pdo.co.om/pdo/