2015 ASME SEC 8 Div 1, Appendix 1-10 in Lieu of UG-37 on normal opening 3

[NamiTS]

I have an existing vessel that a nozzle per UG-37 calcs is grossly under reinforced (3in^2 vs req 13in^2). Using 2015 code Appendix 1-10 it barely passes 28,800 psi vs 30,000 allowable this is apparently what it was designed to. Running CC 2695 on it shows it as overstressed 45,000 psi vs 30,000 allowable. I know it was designed to 2015 code and it was allowed to use app 1-10 in lieu of UG-37 but that provision was removed in the 2017 edition. Should I just accept the app 1-10 results and move on with my life and it will be fine or should I be concerned with this?

 

[TGS4]

This is actually a really good question. The Appendix 1-10 rules were supposed to be the Part 4.5 rules of VIII-2 (as you noted when you mentioned CC2695). That you re-ran the calculations using the VIII-2 rules and still find an under-reinforced/overstressed situation is troublesome.

Are you starting some mechanical integrity work to determine if you have excessive corrosion, and just stumbled across this discrepancy? It might be worth doing a Level 3 FFS assessment (read FEA) on the nozzle, just to satisfy yourself whether it is ok or not.

 

[NamiTS]

Hey TGS4 this issue is prevalent on about 13 different designed vessels all manufactured by the same company all using the same code year. These were 0 CA vessels that just had a baseline done so I was completing models in Inspect and stumbled across this. Doing level 3 on all of the nozzles would be quite expensive in this scenario unfortunately but I'm not completely comfortable signing off on this. I think I'll select the worst case scenario from these and do FEA just to see if it is something I need to worry about. Unless anyone else has ran across this and has some other ideas.

 

[DriveMeNuts]

I'd do an elastic FEM to get a more definitive result.
If it still fails, then perhaps have some sort of committee meeting to discuss how to safely reduce the 3.5x div 1 design margin.

 

[GD2]

Are you doing a design verification of nozzle joints?

The result of the assessment depend on which application you have used Vs what design application the MFR used?

if you are using NozzlePro, WRC, FEA etc. Each application has its own limitations and accuracies.

Do you know what application the MGR used? They cant go grossly wrong with all their vessels.

If you are doing a nozzle verification for the repad only, how did you determine the external nozzle load P?

GDD
Canada

 

[NamiTS]

Hey GD2 late reply but this is just required reinforcement calcs for pressure rating using Codeware Compress/Inspect. The issue is that the 2015 code year allows for Appendix 1-10 to be used in lieu of UG-37 reinforcement. The nozzles are grossly under reinforced per UG-37 calculations and Div 2 stress calculations, but pass appendix 1-10. Appendix 1-10 is what rolled into Div 2 rules but for Div 2 calculations area available around the nozzle opening calculation was changed reducing available area as well as some slight changes on how forces around the nozzles are calculated. These changes to the equations make it fail div 2 but using the same method and equations per App 1-10 it passes. This is why I have some slight concerns over it. These calculations are just due to internal pressure and not external forces are being considered for the calculations.

 

[GD2]

namiTS,
Can you also run WRC 107 in Compress and check? You have already run CC2695.
For external flange loads take help of Dennis Moss handbook unless the client had their own load table.

GDD
Canada

 

[r6155]

Do you have the original calculations and all documents for all PVs in your hands, including the inspection plan?.

Regards.

 

[NamiTS]

GD2,

Running WRC 107/537 load cases using standard API 660 for 600# results in a primary stress of 50,000 psi vs 30,000 psi allowable. Dropping the external loads to minimal doesn't really change much and still results in a primary stress of ~46,500 psi vs 30,000 allowable. If you want to look at it the Shell design is SA-516 70N PWHT 1440 psi @ 130 F, 36" OD, 120" long, 1.375" thick, Full RT, the nozzle is SA-106B NPS 10 Sch 80, distance from centerline to flange is 24", full pen groove weld, 1.125" fillet weld, no internal projection or repad.

r6155,

No original calcs I have the U1-A and Construction drawing for the vessel. Inspection plan would be industry per API-510 of 5 years for external with on-streams done in lieu of internals.

 

[r6155]

Without complete documentation (final data book) implies irresponsibility of the user.
You are working blindly.
I do not like this.

Regards
​

 

[NamiTS]

Unfortunately this is the case for many vessels when acquisitions occur, this is one of the reasons I am doing the vessel calculations. Final data books rarely make it through usually it's just U1-As, in this case I have the ability to contact the manufacturer and receive the calculations but I've already been in contact with them and they stated that the vessel was completed under app 1-10 rules which the nozzle does technically pass barely. My concern is that the nozzle would not pass in any scenario under any other code year except 2015.

 

[r6155]

Should I just accept the app 1-10 results and move on with my life and it will be fine or should I be concerned with this?

Yes, You need to accept.

Regards