B16.5 Flange Radial Hole Drilling for Ports or Lift Lugs

Hi Mumawalde,

I've only little experience in this matter but hope I can give my tiny contribution:

- Does a hole through (Temp or Pressure port) vs. a blind hole (lift lug or lift eye) get handled differently?

AFAIK, increased thickness is required in case pressure taps are required (and note that usually this connection is NPT threaded). We drilled metric threaded blind holes for lifting lugs in B16.47 and B16.5 #150 flanges without any problem. Since blind holes are not expected to undergo internal pressure and are only for temporary use, I suppose that their effect on global flange performance is less harmful, but I'm not sure about this.

- How many holes are allowed, and how to calculate.

I haven't any clue. What I know is that usually lifting lug holes are 1 per flange, while pressure taps are usually not less than 2 and no more than 4 per flange.

- What sized holes?

Pressure taps according to standard likes ISO 5167.Lifting lug holes according to the required lifting lug, which depends on the weight of the device.

- I am assuming all holes in this discussion are located centered between bolt holes, and centered axially on the side of the flange.

Yes, but in case of Flange Taps the hole center must enter the pipe 1" from the face of orifice plate.

Hope it helps

Stefano

I cant really help you on this, but Im eager to see some useful replies, interested in the subject too.
I know of an interpretation on B16.34 flanges where ASME says drilling radial holes is not permitted.
Not sure of if it has a parallel with this ... see interp. 08-4 of this link.
Reply (1) may forbit it, not sure though ..

Thanks to the two people who replied, and I can't believe that there is not more out there for people add.

I personally hoped for some expert comments, as Im really interested in this topic.

ASME forum would a better choice.

Where has the new thread gone to?
Can't find it anymore.

XL83NL said:

Where has the new thread gone to?
Can't find it anymore.

Click to expand...

I cannot find it either.

Here is a link to the a new posting:

I have been watching this thread for a while. I don't have an immediate answer for you. However, if I may make a suggestion: The ASME Code committees do accept questions. The address is: Secretary, B16 Standards Committee, The American Society of Mechanical Engineers, Three Park Avenue, New York, NY 10016-5990. The advice they give on how to submit a question is

Upon request, the B16 Committee will render an interpretation of any requirement of the Standard. Interpretations can only be rendered in response to a written request sent to the Secretary of the B16 Standards Committee. The request for interpretation should be clear and unambiguous. It is further recommended that the inquirer submit his/her request in the following format:
Subject: Cite the applicable paragraph number(s) and the topic of the inquiry.
Edition: Cite the applicable edition of the Standard for which the interpretation is
being requested.
Question: Phrase the question as a request for an interpretation of a specific requirement suitable for general understanding and use, not as a request for an approval of a proprietary design or situation. The inquirer may also include any plans or drawings that are necessary to explain the question; however, they should ot contain proprietary names or information.

Requests that are not in this format will be rewritten in this format by the Committee prior to being answered, which may inadvertently change the intent of the original request.

Click to expand...

Patricia Lougheed

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You cannot make extra holes in an engineered item, like a flange, without FULLY re-engineering it to fully account for the lost metal and strength. Period.

What is normally done is to weld lifting lugs/eyes onto the flange. Just use a qualified WPS and proper preheat [flanges usually are thick enough to mandate preheat]. Simple.

Mumawalde,

What is the Code of construction for this modified B16.5 flange? ASME VIII? ASME B31.3?

Once you drill a radial hole on an ASME B16.5 flange, the standard pressure-temperature rating of the flange is no longer valid. Check the Code of construction for requirements on qualifying a non-standard item.

For a B16.5 flange that is modified by drilling radial holes, I prefer a proof test or burst test to establish the MAWP.

I guess most of us now by know (or already knew) it's not a standard B16.5 flange anymore when you radially drill in some holes; just like when you put an elbolet to an elbow.
now, maybe the best thing to do is follow vpl's advice and ask ASME.

ps; doing the radial hole drilling in flanges is done all the time. last week we received a 3" reactor with about 15 of these kind of radial drilled holes in the flanges, for thermowells to be inserted. as this is a VIII-1 vessel, I suspect the rules may be a little bit easier, as VIII-1 provides more rules/formulae and alternatives than B31.3 for pressure design. Ill have a chat with the MFR and ask him the procedure how do they did it (it's btw a U-stamped vessel).

however, Im especially interested to radial hole drilling in B16.5 when it comes to piping, more specifically B31.3.
another option, though not the same, but having the same meaning, might be the use of bleed rings bteween flanges, and using the tap hole for the thermowell.