How does Division 1 handle external blind holes in flange covers? 1

[Stephen Max]

How does Division 1 handle external holes in flange covers that do not penetrate all the way through? If the hole goes all the way through there are rules for reinforcement. Do they apply to blind holes as well?

Or is there a calculation such as for the minimum thickness over a seal groove?

Thanks.

 

[mk3223]

Where are the external (extra?) holes in the flange cover, i.e. inside or outside the BCD?
How it happened?
Why not to replace the cover without external hole?

 

[Stephen Max]

They are inside the bolt circle diameter. They are for instrumentation and other purposes and are dictated by the customer, who is quite adamant about their presence.

 

[CLFletch]

Closest I can think of is UG-43 (d), though I am not positive it would be considered a studded connection. You may also reference the standard the flange is made to (B16.5), and make sure the flange is still acceptable to use under its rating...

 

[Stephen Max]

I am designing the flange cover according to UG-34, Unstayed Flat Heads and Covers,with reinforcement for those holes that penetrate all the way through according to UG-36. I am not finding any rules for blind holes in flat covers.

The approach I am taking is to do FEA to verify that the stress concentrations at the holes do not exceed the criterion for discontinuity stresses (i.e. Sp < 3S).

 

[SnTMan]

If you can exempt a thru hole, or group of them, per UG-36(c)(3), why not blind holes? You might also read up on tell-tale holes, I have no idea if it would be useful.

Regards,

Mike



The problem with sloppy work is that the supply FAR EXCEEDS the demand

 

[TGS4]

Appendix 30 wouldn't be applicable, so you could apply U-2(g).