Dear all,

If i model a tee in CII , Through a test,i found the CII calculate the weight of the tee in this way:
for example:
a tee: C=1000mm,
M=1000mm

node 10-20-30 then 20-40 ,node 40 is the outlet of the tee

ok,
Weight of tee in CII equal to Weight of the pipe 10-20-30 plus Weight of the pipe 20-40,

in other words, if the main pipe(10-20-30) is 1kg/m, and the outside pipe(20-40) is 1kg/m, then the tee weight is 1kg/m*2m+1kg/m*1m=3kg

I just can't believe the tee is 3kg, it should be less than 3kg, accurate value need more calculation to get.

Do you have any comments?

Best Regards

here goes....
1. Depending on the size of the pipe, this may be an effect from the 'offset'
2.you will always have more material in this type of junction than a standard tee.

Hello whm,
The ANSI B16.9 welding fittings Standard is what regulates the fitting industry in North America. This standards DOES NOT specify the thickness of the fittings except that at the weld line the fitting must match the schedule of the matching pipe to avoid fit-up problems and bad weld geometry.

The effect of this is that NO TWO MANUFACTURERS OF FITTINGS will produce the fittings with the same physical geometry, thickness or crotch radii. NO TWO MANUFACTURERS' fittings will weight the same. If I buy one 6 x 6, schedule 40 TEE from one manufacturer and another 6 x 6, schedule 40 TEE from a different manufacturer, they will both meet all the REQUIREMENTS of B16.9 but they will not have the same weight. One thing we can be sure of is that the B16.9 TEE will have MUCH more than schedule 40 thicknesses at many locations. This is to be able to pass a burst test (this IS a B16.9 requirement). The TEE must carry additional thickness to offset the additional circumferential stresses at the branch point (something like the same way a reinforcing pad works).

The B31 Pressure Piping Codes tell us that the flexibility factor for a TEE is 1.0. We know that is not accurate but that is what we have. Even considering the additional thickness, we know the TEE is more flexible than the Code flexibility factor would have us believe. All these things accumulate to reduce the "theoretical accuracy" of our piping analysis model.

So, how accurate would you want your analysis model to be? The weight of the pipe will vary from one delivery to another. The weight of the fittings will vary. The weight of the valves will vary GREATLY! The piping stress analysis will approximate the distribution of weight across the system but it will never be "spot on". This is one reason why the manufacturers of variable and constant force spring hangers must "build-in" some load adjustment.

Just my opinion.


Regards, John.

Adding to John Breen's comments I would say that we have to rememnber that we are making a model (mathematical), and that gives us a pretty good idea of what would happen with the real pipe. In any case our reults shouldn't be so close that the difference in the Tee weight will compromise the performance of the pipe.

Regards,

Pedro Massabie

Dear all,

I have clearly got what you mean.
model is just a model.
Knowing why the software do in this way make me feel easy and happy,
I think your comments give me a lot, which will help me in my path to be a good engineer.

Thank you all!