ASME8 DIV2 vs MSSP-75 for design a Fitting Tee

[Mm.Kaiser]

Dear friends,
I need help for design a reducing Tee.
As you know according to MSSP-75 (B16. 9) we have to perform a proof test on fittings based on actual tensile strength and nominal pipe thickness.
In my case (Tee 56-30) with pipe line thickness 31.75 the proof test pressure is 300 barg and we use thickness 40 for Tee.
For pipeline the MAWP is 102 bar and 300 bar is so much higher than normal test pressure 1.5*mawp.
So i use elastic-plastic method according to asme8 div2 part5. But In this method applied pressure is 2.4p= 245barg and less than 300.

And now the question:
How i can evaluate the Tee thickness?
Is the Tee Ok if the nonlinear analysis converged with 300 barg? This is what has happend now! But does not converged with pressure more than 305 bar.

Thanks.

 

[XL83NL]

There’s so much contradiction in your post, I dont know where to begin helping you. MSS SP 79 is not equal to B16.9.
You mention pipelines, so I assume you’re working to B31.4 or B31.8, but you haven’t stated this.

Can you start by stating your design code and more details on the application? Like sketchy, design pressure and temperature?

 

[Mm.Kaiser]

I'm sorry xl83nl if i made you confused.

I told mss-sp75 not 79! And also i don't want to design pipeline because it's thickness is clear.

Just the project is: designing TEE 56'' and performing proof test on it according to mss sp75. So i want to know steps to design Tee and evaluate it's thickness.

I want to be ensure that if my elastic-plastic analysis convrged with mss sp75 pressure, the TEE does not explode in proof test

We have blinded the TEE with Cap and it is still waiting for me to insert proof test pressure 300 barg.

Tnx

 

[LittleInch]

The proof test is there to provide a fairly brutal test of the geometry and thickness of your tee.

The test pressure is set by the equation in section 2.2. you appear to calculate this as 300 bar

the MAWP of the pipe is irrelevant as there may be many factors as to why your pipe is that thick but only rated for 102 barg (design factors, corrosion allowance, lower SMYS than your tess)

You haven't stated the SMYS of your pipe or the actual tensile strength of your fitting.

Just stick to MSS SP-75 and test the thing in a secure location in case it goes bang.

Only other way is to measure sh1t out of your tee for thickness and build a 3d FEA model of the tee and subject it to test pressure and see if it thinks it will go pop.

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

 

[Mm.Kaiser]

Littleinch,
1-What do you mean by sh1t?

2- I have calculated proof test pressure from para. 4.3 not 2.2! Because we have to perform a proof test.

3-my problem date is here:
- Attached pipe thickness =31.75 for api 5L X65
- Tee 56' thickness = 40 mm
- Actual tensile strength =616mpa so proof test pressure is 302 barg

I made a 3D model with true stress-strain curve and performed a nonlinear analysis with 302bar pressure. Analysis converged so hard after so much iterations. (you can see in attached image)

Does it proove that my Tee is admitted with mss-sp75 rule? And who insures me that the Tee does not explode in real test? I should retell this note that the solution does not converged with pressure more than 305barg.

 

[LittleInch]

Sorry - slang - I meant do a lot of UT measurements.

But I think you're using the wrong thickness - t in the equation is the nominal pipe wall thickness of the pipe that the fitting is intended for - surely that is 31.75mm

Do you have a drawing of this tee?

you test it making sure that it doesn't hurt anyone or thing if it does break, but energy in a hydrotest is quite low - just do it behind some concrete walls.

If it passes the analysis according to section 2.5 then you might not need to proof test it.

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

 

[Mm.Kaiser]

Thank you all for the help.

 

[TGS4]

What shape does your stress-strain curve take beyond the true ultimate stress? Think about what that means in the context of your evaluation?

Also, have you been looking at Protection Against Local Failure, which incorporates a local strain limit check?