Hello, Guys. I am new here and have 3

[herreraam1]

Hello, Guys. I am new here and have, hope so, a silly question.
In a branch connection for a pipeline that I am checking for pre-commissioning I found that the run pipe is API 5L, X-52 and the branch pipe is API 5L, grade B.
Looking at the construction code, ANSI B31.3, and associated specifications I didn´t find no information about this but, four out five examples shown in the code´s Appendix H highlight that both pipes have the same specification.
Treating this with the designer has take some seriuous discussions but no agreement has arouse.

Please, I´d like to know your comments. Thanks in advance.

 

[pennpiper]

herreraam1,
What is the size of the Run Pipe?
What is the size of the Branch Pipe?
Is this pipe already purchased and at the jobsite?

Sometimes its possible to do all the right things and still get bad results

 

[herreraam1]

Hi, Pennpiper.
As I wrote, we are in the pre-commissioning stage, so the pipeline is already constructed.
The run pipe is 26" and 0,4382" thick. The branch is 6" STD. The reinforcing pad is the same material and thickness as the run pipe, in accordance with the available records.
Thank you for your fast reply.

 

[LittleInch]

herreaam1

If this is a pipeline then it should be B 31.4 or 31.8 as the design code, not 31.3 which is a piping code.

I can't see a big issue, but "branch connection" is a bit vague. Do you mean literally a pipe and re-pad or are you using a weldolet.

A drawing, sketch or some design info like penn piper says makes it all much clearer.

What is your concern?

So long as the branch pipe is properly sized, the different material grade is irrelevant as far as I can see.

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

 

[zdas04]

Pipe grade is an essential variable in welding procedures. As long as the welding procedure is the proper one for welding an "X" grade to a "B" grade then there is no issue.

[bold]David Simpson, PE[/bold]
MuleShoe Engineering

In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual. Galileo Galilei, Italian Physicist

 

[herreraam1]

Thank you guys for your attention.
Here's a picture of the mentioned branch connection. The pipe run is 26" grade X-52 and the branch is 6" STD, grade B.
This is a valve station that the customer required to be constructed in accordance with ANSI B31.3 since it is inside a cryogenic complex. The pipeline was constructed in accordance with ANSI B31.4
My concern is related to the materials compatibility from the mechanical point of view. The project´s piping class asks to mantain this during the pipeline (NGL) construction.
I agree with Mr. David´s comment related to the WPS.

Again, thank you all.

 

[KevinNZ]

The piping designer needs to have completed the branch reinforcing calculation using the allowable strength of grade B for the branch and X52 for the main. If not the grade B branch maybe too thin.

 

[LittleInch]

I don't understand this bit "required to be constructed in accordance with ANSI B31.3 "

Do you actually mean designed and constructed?

If so the wall thickness of this section of pipeline will be thicker than the B 31.4 section due to the way the two codes work. This is normally not a good idea as it can impact of the potential for pigging due to change in ID.

Also these types of branch connections are not a preferred technique due to the potential for either the pipe or bits of the welding to stick down into the main pipeline thus causing damage to any pigs. On piping no one really cares but pipeline does. Use of a reducing tee or a weldolet is preferred.

The fact that this thing is inside a facility should be irrelevant.

So long as the design and the WPS is Ok, then there shouldn't be an issue. Having a smaller diameter pipe with a lower SMYS isn't unusual.

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

 

[weldstan]

Since you are in the pre-commissioning phase, perform some calcs to verify correctness of design. Agree with LittleInch that the design is not the best but it could meet Contract.

 

[herreraam1]

Thank you all, guys for your fast reply.
Your comments made me to see it better.

 

[LittleInch]

Ok, A couple of comments for next time you post:
1) Put something decent in the title box - this one should be " Header and branch design"
2) Try to put relevant information and pictures, drawings etc in the OP. Which design codes matters and pictures / drawings tell a thousand words.
3) Some sort of background and what the issue is and what you've already considered helps to focus the answers or they can go a bit off the wall, or not get very many.
4) some feedback on what you're going to do or did do, even if it's weeks later is much appreciated - all the comments come free so decent feedback is part of the bargain you strike.

LI



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

 

[DSB123]

Just wanted to point out the fact that there is no such Code as ANSI B31.3 or for that matter ANSI B31.4. The correct designation is ASME B31.3 and ASME B31.4.

 

[XL83NL]

Im still confused as to what was the OP's real question; couldnt filter that out from the replies. May be just me ...

 

[LittleInch]

I think the gist was that there were two different pipe grades being welded together at the branch connection, was that OK?

"My concern is related to the materials compatibility from the mechanical point of view. "

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

 

[XL83NL]

mmm, OK.

 

[amlc1984]

What about the piping class or piping specifications of the detailed engineering?. It should specify which material is the proper one for that Tee connection.