Pipe Minimum wall under a blind counterbore 1

[JAYDEE23]

Before I proceed with burst or FEA proofing, I wanted to see if anyone is aware of any methodology or equations that cover this situation in ASME.
My wall thickness under a blind counterbore is insufficient when run through a basic minimum wall thickness calc for pipe.
Ive reviewed B31 standards and Sect VIII and cannot find anything that I can see that applies.
I realize this is not an appropriate use of a branch reinforcement calc, but I ran one anyway.
The configuration and calc are attached.
Does anyone have any ideas for design by number for this situation outside of the standard minimum required wall thickness?

 

[SnTMan]

JAYDEE23, have you looked at Div 1 Appendix 32?

Regards,

Mike

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[JAYDEE23]

SnTMan
Unfortunately, the Sect 32-5 required blending between the LTA and thicker section is something I cannot comply with
It was a good read though and something I was not aware of. Thank you!
I'll continue to study it a bit though.

 

[r6155]

Try with a flat circular plate UG-34(c)(2) with d= 1"

Regards

 

[LittleInch]

What exactly is a "blind counterbore"?

Do you have a drawing?

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

 

[r6155]

See drawing attached by (OP)

 

[LittleInch]

Ha, Sorry, missed that on my phone.

OK, SO what design code? - B31.1?

This looks like some sort of pipe spool with a strange plug being set into the spool.
Is is welded into the tube?
What's the 1/8" thing?
Why can't you use a standard set on fitting?


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

 

[JAYDEE23]

The product is a turbine meter, essentially a 10" Sch 80s 600# Pipe Spool.
The "Blind Counterbore" is a counterbore that only penetrates the pipe partially from the outside.
This counterbore is fitted with a sensor that magnetically senses a spinning rotor inside.
The thickness under the counterbore is required to be 0.125" thick for sensing purposes.
Code of construction is B31.1 2018.

 

[SnTMan]

JAYDEE23, given that you have a "non-standard" design feature, it perhaps is not necessary that whatever Code rules you can apply need be "swallowed whole".

So for Apx 32 you might neglect the blend. Apx 30 refers to "Drilled Holes Not Penetrating Through The Vessel Wall". It requires the minimum remaining thickness to be 1/4". But given that your are more-or-less in a U-2(g) or equivalent situation and that your 1/8" is absolutely functionally required, if the calculated minimum thickness (by what ever means) leaves a sufficient excess, you could call it good.

Some creative application of the rules is not unheard of

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[JAYDEE23]

SnTMan
I totally agree. Being creative with the texts is essential. Depending on the audience, however, it can get hairy.
In this case, I am putting together a package that will be used to register the design in Canada (CRN).
Most importantly, I need to satisfy myself, ensuring I am confident in the design.
But the unknown for me is going to be the folks reviewing the design on the Canadian side.
They typically balk at anything that does not have an easily correlated code section referenced.
Once I get into explanations and justifications of my methodology, I lose them. Or rather, the process gets to be rather laborious and lengthy.
I have had rejections from the Canadian registration folks for absolutely frivolous reasons.
I always succeed, eventually, but I just want to avoid any headaches if possible.
I very much appreciate everyone's feedback on this!
Ill take more if you got it

 

[KevinNZ]

You could adapt the code calculations for a reinforced tee to see of you need reinforce around your hole/pit. But also check that 1/4" section does not pop out, you could use the code blank/blind calculation for that.

 

[SnTMan]

Oh. CRN. If I'da known that I wouldn'ta said anything

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[JAYDEE23]

SnTMan
The uncertainty of those design reviews is what makes it exciting! Haha

KevinNZ
Are you referring to B31 case 202, reinforcement of a tee? If so, Ive worked with those calcs in recent years for another product and I am not seeing how that would apply here.
Can you explain a little further?
And what blank/blind calc are you referring to? Flat head?

 

[SnTMan]

Seriously, circular plate thickness (Roark / UG-34) backed up by shear stress at the perimeter may be the most practical thing. Start simple for your reviewer. Easier to complicate it later than to simplify it later

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[JAYDEE23]

SnTMan
I have a shear calc ready. I will add the plate thickness. Thank you. You have been very helpful!

 

[SnTMan]

Nice of you to say so Best of luck

The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[GD2]

Jaydee23,
The 0.13in thickness must meet the minimum design thickness required by the Code. You know the design conditions. all you need to do is use the code design thickness equation and calculate what's the minimum design thickness should be.

Play with the counterbore depth and increase the pipe wall thickness. The connector is a non-pressured component and you have a fillet weld to attach it.

As soon as you make a through hole, the configuration will act as a tee, and the 1" MPT connector wall thickness will provide the design thickness required.

GDD
Canada

 

[GD2]

Oh! I just noticed in your work table that the application had already calculated the minimum required wall thickness of 0.22 in. This is the wall thickness you need to have instead of 0.13 in .

And wait. What is that 1" MNPT Fitting Header Reinforcement Analysis? Why are you doing this? This is not even a pressure part and what is your table calculating without any pressure on it?

Now I understand the reason to balk.

GDD
Canada

 

[FacEngrPE]

There is a situation not discussed above that might or might not come into play.
Your threaded boss is unpressurized, but it might be at a different temperature than the fluid filled pipe. If the temperature difference is large, the differential thermal expansion can create stress that might not show up in code calculations. In the case I was involved in the result after about 6 months was a through wall fatigue crack.

 

[JAYDEE23]

FacEngrPE
Design is 325F and Operating is 41F.
Operation is continuous and will be @ 41F most if not all of the time.
Good point, but I do not have any concerns about the fitting above the flat bottom counterbore.