Opening in standard blind flanges 4

[Amr Shams]

I am designing a pressure vessel using compress software .the PV is 24" OD and has a bolted cover.
we want to use standard slip on flange & blind flange but we need to make an opening in the blind and we can't do it in compress.
1) can we use a UG-34 cover with the same dimensions of standard blind flange to easily make an opening and in fabrication process use standard blind flange and make the opening for nozzles.
2) Why did compress prevent to make opening for nozzles in standard blind flanges? Is it forbidden by code ?

 

[LittleInch]

This might be better asked in the Boler and PV forum, but also add what the MAWP is for this PV.

1) I can't see why ont if the blind passes all the checks
2) Don't know, but often blind flanges to ASMe B 16.5 "fail" in ASME VIII. Drilled holes are limited in size in ASME B 16.5

What sort of "opening"?

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

 

[david339933]

Standard Designation: BPV Section VIII Div 1
Edition/Addenda:
Para./Fig./Table No:
Subject Description: Section VIII, Division 1 (1998 Edition, 2000 Addenda); UG-34 and UG-39
Date Issued: 12/07/2001
Record Number: BC01-336
Interpretation Number : VIII-1-01-105
Question(s) and Reply(ies):

Question: A circular blind flange, used as an unstayed flat head, has a nozzle attached at its center using a full penetration weld, or a partial penetration weld, or a screwed connection. Are reinforcement calculations per UG-39 of Section VIII, Division 1 required for this geometry if the opening in the blind flange is of a size that is permitted in the flange standard referenced in UG-34(c)(1)?

Reply: No.

Standard Designation: BPV Section VIII Div 1
Edition/Addenda:
Para./Fig./Table No:
Subject Description: UG-34 and UG-39, Blind Flange Thickness
Date Issued: 01/05/2009
Record Number: 08-1562
Interpretation Number : VIII-1-07-69
Question(s) and Reply(ies):

Question: If an opening in a blind flange is greater than that allowed by provisions of ASME B16.5, is it required to use UG-34(c)(2) and UG-39 to determine the required thickness and reinforcement in lieu of the dimensions and pressure ratings that are given in B16.5?

Reply: Yes.


Standard Designation: BPV Section VIII Div 1
Edition/Addenda: 2015
Para./Fig./Table No: UG-36(c)(3) & UG-39
Subject Description: Reinforcement of Openings in Standard Blind Flanges
Date Issued: 04/02/2019
Record Number: 17-2457
Interpretation Number : BPV VIII-1-19-05
Question(s) and Reply(ies):
Question 1: An ASME B16.5 or B16.47 blind flange has openings that do not exceed the size and spacing limits in UG-36(c)(3) and do not exceed one-fourth the head diameter or shortest span. Is it acceptable for Section VIII, Division 1 construction to use the ASME B16.5 or B16.47 pressure-temperature ratings for this blind flange without performing any additional design calculations?

Reply 1: No

Question 2: An ASME B16.5 blind flange has an axial hole in the center. The hole size exceeds the size limits in UG-36(c)(3), but is permitted for a blind flange used as a reducing flange per ASME B16.5. Is it acceptable for Section VIII, Division 1 construction to use the ASME B16.5 pressure-temperature ratings for this flange without performing any additional design calculations?

Reply 2: Yes

Question 3: An ASME B16.5 reducing flange requiring a hub has an axial hole in the center that exceeds the size limits in UG-36(c)(3). Is it acceptable for Section VIII, Division 1 construction to use the ASME B16.5 pressure-temperature ratings for this flange without performing the reinforcement calculation per UG-39?

Reply 3: Yes

 

[Cobra17]

Compress doesn't allow a B16.5 flange to be altered, so you have to do it as a UG-34 cover. However, if the opening does meet the requirements of B16.5 table 6, you don't need to add the opening for area replacement calculations, but you might need to prove UG-45 and weld size requirements, which you can do using the UG-34 cover, even if it does fail area replacement and the cover doesn't meet thickness requirements because it's still a B16.5 flange.

 

[Amr Shams]

the opening in the blind flange is for nozzles center and off center. not tapered hole as table 6 recommends.
so if the opening is for nozzles i can't replace the UG-34 cover in design with blind flange in fabrication process?

 

[Mussha]

You can use UG-34 design cal. for blind flange. To provide center opening cal. t by UG-45 and satisfy the UG-44 equation, edition 2021.

 

[saplanti]

Why do not look at Timeshenko's book, Plates an Shells or Roark's book Stress and Strain. They have calculation methods for circular plates with inner holes under several loads cases. You may be able to combine load cases and find combined stresses and deflections. If you consider outer edge is free to rotate you can get thicker plate by using code allowable stress.
I trust this can give you an approach to solve the problem.

You can additionally check the calculation thickness with standard blind flange thicknesses and use the suitable class on both sides, WN and blind.

 

[Mussha]

If you are not satisfying UG-36 cal. then go for FAE separately for multiple opening in blind flange.

 

[david339933]

If you can't design a vessel because Compress has not included it in the software package, then I suggest they revisit the new Appendix 47.....

SKMoshin, what equation in UG-44? For external loads applicable only to weld neck flanges?
UG-36 is not applicable to reinforcement of flat heads and covers, that is UG-39. You also can't circumvent the Code rules by using FEA.

 

[XL83NL]

If you can't design a vessel because Compress has not included it in the software package, then I suggest they revisit the new Appendix 47.....

Spot on

Huub
- You never get what you expect, you only get what you inspect.

 

[Amr Shams]

the fabrication period is too short.So we need to use a blind flange instead of UG-34 cover for quick supply.but we had a doubt that the blind flange can't has opening for nozzles because it doesn't meet the requirements of table 6 in B16.5 .
I already used a UG-34 cover in design which worked perfectly but it will have a large supply period to be fabricated.
So is it possible to order blind flange instead of UG-34 Cover ? (in fabrication stage)