Large offset opening in blind flange with weldolet for reinforcement 2

[boofi]

Good morning y'all.

I have searched through this site and read some good information on tapping holes or nozzles in blind flanges.

Due to space requirements, we need to reduce from 16" to 10" within a 12" span. Originally, I was going to use a 16" blind flange, a 16x10 weldolet (flat), a length of 10" pipe, and a 10" flange. My question is, with the weldolet acting as reinforcement, do I still need to do thickness calcs for the (formerly) blind flange per UG-34? My gut feeling says yes, because the offset hole automatically means this is no longer a 16.5 component but a Section VIII component. I am fairly certain the 16" CL150 blind flange will fail on these calcs. Will I have to get a thicker flange then, regardless of the reinforcement provided?

 

[LittleInch]

Yes

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

 

[boofi]

Okay. Thanks! Too bad my calcuation software is corrupted lol.

Followup: There was a very long discussion here:

https://www.eng-tips.com/viewthread.cfm?qid=371342

We use "bleeder blinds", or 16.5 flanges with a tapped hole on the face, nipple, and valve, all over our plant to make sure lines are clear before working on them. See below for example. The discussion above seems to indicate that any size 16.5 blind with a hole cut into it off center would require calculations. Does this mean all of our bleeder blinds need to be evaluated? It's unfortunate that the ASME committee didn't give provisions in their interpretation for something as convenient as a bleeder blind. Practically, we have never had an issue with these.

https://image.shutterstock.com/shut...-of-pipeline-for-pressure-test-1287627913.jpg

 

[XL83NL]

There's been lengthy discussion in the past on using weldolets for anything other than (a fitting on) piping. Simply put, dont use it for anything other than piping systems. Especially not something flat like a blind flange. Olets are designed for piping, not vessels or flanges.

before working on them

Do you leave them on during process? Then they become part of your precess (requirements) and cant be seen as temporary testing devices.

The discussion above seems to indicate that any size 16.5 blind with a hole cut into it off center would require calculations.

That's incorrect. Read the thread (371342) again, Im sure it will be in there, but if the hole falls within the limits of table 6 of B16.5, youre OK without any calculation. Be aware table 6 onl;y applies to centered holes - if the hole is eccentric, a calculation will formally always be required.

Does this mean all of our bleeder blinds need to be evaluated?

From a B31.3 point of view (which relates to new construction), yes. Since you're the owner/user, Im not sure if that provides you with other/additional options to waiver certain B31.3 requirements?

Practically, we have never had an issue with these.

There's a section in 304.7.2 that may provide a waiver for that.



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

 

[LittleInch]

It's the offset that's the problem.

In reality it happens all the time, but try not to knock one off.

Screwed in bleed valves might be better.

[URL unfurl="true"]https://res.cloudinary.com/engineering-com/raw/upload/v1641566250/tips/BYjSE1fkQAEAzuPR9_mayjdg[/url]

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

 

[KevinNZ]

If you get a full hub blind flange you can put any size hole in it. It's still be a B16.5 flange so no calculations required. (not 100% sure about the hole offset)

 

[Cobra17]

for the hole offset, see interpretation record 17-1535, question 2:

Qoes ASME B16.5-2017 prohibit the NPS 3 hole (in the above application) from being offset from the center of the NPS 24 blind flange?
R: No.

search here:

https://cstools.asme.org/Interpretation/SearchInterpretation.cfm

 

[XL83NL]

I could only access that Interpretation by searching through the 'Check the status of your Pending Interpretation'-field.
Is this Interpretation already actually published?

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

 

[Cobra17]

it is a published interpretation. Enter 17-1535 in the "record #' field and hit search.... it should come up.

or click here:

https://cstools.asme.org/Interpretation/InterpretationDetail.cfm?TrackingNumber=16353

 

[XL83NL]

Thanks. This is an interesting Interp. which I’ll gladly use in the future.

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