ASME Standards Flange and opening for Bolt Hole

[MDKARMD]

HI,

ASME section VIII Div1 - Vessel.

As a normal practice or per most of the client specification, the manway cover will be standard blind flanges with additional threaded hole for jack screw.(jack screw is provided for dismantling purpose.)

So these additional opening of jack screw will make the flange to non-standard one.
In this case how to comply the code requirement??or how to check the flanges for these additional hole.

Can any one share any interpretation of the code or any reference document.

Thanks.
Kar.

 

[TGS4]

Appendix 2.

By modifying the flange you have, as you said, made it nonstandard, and therefore you are unable to use the P-T ratings in B16.5/B16.47.

 

[LittleInch]

But ASME B 16.5 section 6.12.2. allows
"Holes may be tapped
in the wall of a fitting if the metal is thick enough to allow
the effective thread length specified in Fig. 3 (Fig. II-3 of
Mandatory Appendix II)."

Therefore so long as it complies with 16.5, then you're Ok?. Probably why manholes are 24"....

If you search this forum for holes in flanges you get a variety of opinions, some say is covered, others say you need to do a calc.

May be better to weld on a lug or use a flange spreader rather than drill a hole if you want to avoid any issues

I'm pretty sure I know what you're talking about, but can you upload a sketch / drawing so we're all clear please.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[TGS4]

LittleInch - I do not believe that 6.12.2 is in reference to holes through the flange. There have been multiple discussions about whether or not pressure taps in flanges comply with B16.5...

I agree that lugs or a flange spreader are better options.

 

[LittleInch]

I fully accept there are many opinions, but a blank flange is a "fitting" and the drawing it refers to, whilst showing a curved body doesn't limit itself to a curved fitting and provides for min thicknesses up to 2" hole size. The better types of manway covers clamp onto the outside or weld on a ring or other attachment and don't drill holes to avoid this.

The key thing for me is where you're drilling this hole, how big it is and how it affects the structural strenght.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

 

[SnTMan]

Unless this were some unusual service I would drill & tap a couple of 3/8" or 1/2" on or outside the bolt circle and not think twice about it, keeping in mind that jackscrew holes are put in Apx 2 flanges all the time with no accounting for them.

Even if treated as openings per UG-39, they are not subject to pressure, and therfore those rules cannot be said to exactly apply.

Regards,

Mike

 

[MDKARMD]

its all about standard flange;
What is the case of non standard flange.(ASME Secion VIII Div-1 appendix 2).
How to check the strength of flange if there is multiple drilled hole on bcd of flange.

 

[SnTMan]

Please note: In Appendix 2 flange design the bolt holes themselves are not there. A couple more that are also not there won't make any difference.

Likewise, in my opinion, they won't make any difference in a standard blind, except maybe, maybe, in the most extreme services.

Regards,

Mike

 

[MDKARMD]

Dear Mike
I fully agree with you...however its need some justification or document reference to accept a 3rd party...

 

[SnTMan]

Sorry, engineer, not a lawyer...

Good luck.

Mike