Area Replacement Rule, WRC, and FEA 1

[sxz]

Hi, I have a nozzle reinforcement calculation. As per the UG-37, the area replacement rule, Aa < Ar, it fails, but WRC or FEA results pass. Can I use the WRC or FEA result for fabrication?
Thanks.

 

[SnTMan]

sxz, I infer your Code of construction is Sec VIII, Div 1 from your reference to UG-37. See UG-1(3). If you are representing your vessel to meet this Code, short answer is, no, you may not.

Regards,

Mike

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

 

[sxz]

Thanks for your response!
Yes, the existing vessel (built in 1975) with nozzle modification will be designed by ASME VIII-1.

 

[TGS4]

In general, I would agree with SnTMan that the answer is a pretty hard no.

However, if you were to design this to the 2019 Edition of Division 1, then you could apply the provisions in UG-16(a) to make use of Appendix 46. From there, I would take a first pass at the nozzle reinforcement rules in VIII-2 (specifically Section 4.5, as noted in 46-3(a)(1)). If that doesn't get you to where you need to be, then you could apply the Design By Analysis rules in VIII-2, per 46-4. However, I would note that you would probably need to re-do the FEA, as I highly doubt that it was actually compliant with the requirements as listed in 46-4.

 

[SnTMan]

Presumably the work would be done under the NBIC, so there is that consideration as well.

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

 

[DriveMeNuts]

For the design case of reinforcing the nozzle for 'internal pressure only', Appendix 46-4(a) specifies:

"46-4(a) Division 2, Part 5 (FEM) shall not be used in lieu of the design thickness requirements of Division 1 or Division 2, Part 4."

My interpretation of this is that design by rule (Div 1 or Div 2) needs to be used for simple pressure only reinforcement of a nozzle. You can't use FEM.

For the design cases where loads are applied to the nozzle then 46-4(a) doesn't apply and therefore FEM is acceptable.

 

[sxz]

Thanks for all of your inputs. So I have to add a repad on the integral nozzle (HB type) to meet the requirement of area replacement rule.

 

[TGS4]

sxz- no. That's not what we're saying, at all.

Have you performed the calcs the Division 2, 4.5?

 

[sxz]

TGS4, 46-3(a), The thickness shell sections was not determined by Division 2, It was by Division 1.

 

[TGS4]

That's not a problem. Have you performed the calcs per Division 2, 4.5?

 

[sxz]

My COMPRESS doesn't have License for Division 2, not performed.

 

[TGS4]

Do you have a pencil and paper? Perhaps a calculator?

Putting a repad on an integral nozzle is a really bad idea - if I were the customer, I would not allow it.

 

[SnTMan]

I was kind of cringing over that

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

 

[david339933]

What kind of pressures are you dealing with....What is the rating of the flange? HB are pretty thick.

 

[sxz]

DP=320 psig, DT=650F, ID=120", SA-516 Gr70, Allowable stress: 17,500 psi, Shell measured thk=1.334" (nominal 1.375"), future CA=0.125". New Nozzle, SA-350 LF2 CL1, 12", 300#, HB neck thk: 1.97", CA=0.125", allowable stress: 20,000psi. Nozzle loads: Pr=6600 lbf, VL=Vc=3960, Mt=166,320 lbf-in, ML=Mc=117,588 lbf-in.

 

[david339933]

Where did you get the thickness?
HB neck thickness is not 1.97"....HB is 2.28" Thk.

 

[sxz]

Bore ID =12, D=15.94, t=1.97"

 

[SnTMan]

If you can use a custom nozzle forging and weld neck flange you can get any dimensions you want.

Oh. Nozzle loads. Another kettle of fish can of worms altogether.

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

 

[david339933]

Bore of HB is not 12"....Bore of LWN is 12"....Bore of HB is 11.38". I have no problem eliminating pad with info you gave. Straight replacement only....not opening the can of worms...

 

[sxz]

Thanks for your input, the customized bore HB flange had been ordered.