Calculating Wall Thickness and Reinforcement? for a Pipe Welded WYE 1

[JAYDEE23]

Guys please help direct me.
We are remaking an old B31.1 pipe section that had the following configuration on the sampling tap.

90 degree welded WYE 2" Sch 40S 317SS (made from 3 pipes)
welded to
4" Sch40S 317SS Header pipe.

I am good with the Header and Branch Min wall thickness and reinforcement calcs.
I cannot for the life of me find any direction on equations for a WYE.
I see the forged WYE are all proofed by FEA or Burst test.

Anyone know if there is any "by paper" design equations for wall thickness requirements/reinforcement for welding 3 pipes together to make a WYE?

I will likely go with the forged purchased WYE, although ridiculously expensive, but I am curious to know if there is any design guidance out there for making a WYE from pipe.

 

[XL83NL]

No sure what your configuration looks like, but B31 has released a code case not so long ago for the design of wyes. I don’t have the link at hand but you can find it via my profile in one of my recent threads I made on that topic. I’m not 100% sure if the code case is also supported for B31.1, so check that as well.

Got it:

https://www.eng-tips.com/viewthread.cfm?qid=437975

 

[JAYDEE23]

XL83NL
This is excellent. It is for a forging but it gives me options outside FEA and burst test!
Thank you very much!!

 

[XL83NL]

There’s a way to thank for a post you consider valuable ;-)
Anyways, welcome

PS: the CC mentions B31.3, so I’m reluctant to think it may be used for B31.1.

 

[JAYDEE23]

Well it was a great post
Im sorry i spent so many hours searching on line and in forums.
Thanks again!

 

[davefitz]

We have seen medium term failure indications on welded wyes and tees in high temperature service, and generally replace these fabricated fittings with forged fittings. The " weld creep strength reduction factor" should be utilized on any weld that is not a true butt weld for creep strength enhanced alloys operating above 800F

"...when logic, and proportion, have fallen, sloppy dead..." Grace Slick

 

[weldstan]

Agree with davefitz. We had premature failures, cracking in the weld reinforced crotch and near long seam welds after less than a year in high temperature service. These were much larger than the 317 ss wyes. But do beware of welding distortions on the thin wall ss piping and its effect on service life.

 

[JAYDEE23]

Maybe I do not have enough experience with code cases but I am really surprised by the amount of detail and work the committee has provided in this code case #202.
I am getting wildly different quote values on the forged 317 SS 2" WYE.
Ranging from $400 to $7500.
Still trying to figure out what is going on.
Good to know I can machine one myself and get a CRN on it!

 

[XL83NL]

Which material requirements and details have you provided with the RFQ?

 

[JAYDEE23]

90 degree forged WYE 2" Sch 40S F317SS

Design Calculations to be provided with product
800psig @300F

I was offered a block style for $4500
And fully outer contoured machined for $7500
That is each!
And I am buying 20+ of these so that price is not going to work for me.

I was just quoted $400 each today for them.
We shall see what is going on soon....