Wall thickness of the Reducing Tee?

[nickcaiyh]

Dear professionals,

Would you please do me a favor on my question about reducing tee wall thickness?
For example, a 10"x4" reducing tee, we have pipe schedule 10S for 10" pipe and 40S for 4" pipe, so,we may need a 10S x 40S.

We know that the 4" Sch40S is thicker than 10" Sch10S, so how could the reducing tee be?

Manufactory by 40S pipe and leave a 10S BW end for header? Or really make different wall thickness tees on header and branch.
This is also very important information for piping stress analysis on 3D modeling in CAESAR II.

Thanks in advance!

Nick

 

[BigInch]

Buy a Sch40 Reducing tee. The 4" outlet will be 4" x sch40 wall thickness. Weld a 4" x sch40 pup piece (6"-12" in length) to that. Taperbore the pup at 1:4 so that the pup's outlet is no greater than 3/32" different from the 4" sch10 wall thickness.

 

[LittleInch]

Seems strange that you have a small, thick pipe joined to a larger thinner pipe??

Anyway I think BI misread your OP, but you could either get a ached 10tee and then machine down the sch40 pipe to meet the sch 10 thickness at 10". I don't have a guide in front of me do not sure what the actual thickness difference is but it can't be much. Actually 4.2mm to 6.02 mm.

Or get asch 40tee and machine both sizes to meet the matching wall thickness.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[rconner]

In general terms one can't really automatically assume smaller piping can simply be welded into or onto a larger cylinder with equal pipeline security at the connection. Cutting a hole into a larger cylinder removes part of its wall that is to/was previously supporting piping loads, and also makes a point of stress concentration, a weakening that may or may not be replaced by the local combined strength of the larger cylinder wall and wall thickness of the branch and its weldment near the connection. Therefore, (while I don't know about Caesar II I guess an analysis by e.g. by at least design method details of Sec. VIII of the ASME Unfired Pressure Vessel Code, or Section 13 of AWWA manual M11 if for water service etc, is generally advisable. That being said, I suspect a small diameter tee such as you describe may well have fairly good at least internal pressure strength for at least light piping loads.

 

[nickcaiyh]

Dear BigInch, LittleInch and rconner,

Great thanks to all your responds.

I would like to describe my questions more detail. In the piping material specification, the pipe wall thickness for 4" is Schedule 40S, for 10" pipe, the wall thickness is 10S, and there shown in the branch table that reducing tee applied for 10"x4", so a thicher wall branch and thinner header tee required.

When performing piping stress analysis, that reducing tee were also modeled. The SIF according to ASME B31.3 for tee is so not reasonable, Hope it wiill be revised in next version. Sometimes, without FEA tools on calculate the real SIF for tee, we just make a thicker wall thickness tee instead incase if piping stress exceed on the tee.
For the example 10"x4" Sch10SxSch40S reducing tee, we manualy changed the header of the tee from 10S to 40S and make a 10"x4" Sch40SxSch40S tee in CAESAR II to pass the stress analysis.

For such case, according to LittleInch, do we should better to use weldolet instead of reducing tee with a thicker branch and thinner header?
Another assumption is that the reducing tee manufactory could offer the 10"x4" Sch40SxSch40S reducing tee and leaving the 10S BW end on header for welding to pipe. If this assumption is correct, we will pay much attention on piping stress analysis in CAESAR II to model the correct wall thickness for tees.

Thanks and Best regards,

Nick

 

[Ady111]

I have kind of the same issue too. I wonder if the solution to chose the tee with greater wall thickness and make an inside bevel to the other ports like for reducers is a good one.

 

[XL83NL]

In such cases we always specify the tee to the greatest schedule size of both the rund and branch pipe (in this case S40), and have the outlet with the thicker wall (in this case the branch, which needs to be S10) machined back.

Another thing; on a recent job we did we had 10x4 tee's. I had a time finding any (EU-based, Netherlands). Actually, we didnt one at all. Might be a local thing, but even though theyre in B16.9, doesnt mean you can get em. Another example would be a 3x1 tee which isnt in B16.9, but can be readily purchased.