How can we design a flange used as Quick opening closure having slotted bolt holes

[SyedZainAli]

Dear All
I am working on a design project that comprises of a quick opening closure having slotted bolt holes and instead of having stud bolts it has Eye bolts eye side of the bolt is attached to the shell so that we can instantly open all bolts i am having trouble in designing such type of the flange coz ASME Section VIII Div. 1 Appendix 2 donot address it therefore i am attaching the sketch of the flange having slotted bolt holes

Please suggest me the design procedures for that flange

http://files.engineering.com/getfil...fa-c183d954a263&file=Quick_closure_sketch.pdf

 

[prex]

A = outside diameter of flange or, where slotted holes extend to the outside of the flange, the diameter to the bottom of the slots

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[SyedZainAli]

Slots extends from BCD to the outside diameter of the Flange and blind Flange as you can see in attached sketch

 

[prex]

Yes, ditto. That's exactly what that sentence provides for.

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[LittleInch]

In other words for the purposes of the calculation, the OD of the flange is much less than the OD as you have drawn it, but is reduced to the inner bolt hole (BCD minus diam of bolt hole). Because you have cut the flange, the calculation assumes that the flange no longer applies sufficient force on that section beyond the bolts to be of any use.

My motto: Learn something new every day

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

 

[marty007]

This is one of the reasons I read these forums. I've never had to design a flange with slotted holes like this, so have never looked into it. But now that I've heard of it, it'll pop into my head if I ever run into this in the future.

Thanks guys.

 

[SyedZainAli]

So guys
Any solution?

 

[LittleInch]

Yes,

You design the flange as though the outer edge of the flange in the calculations is the diameter of the inside of the bolt holes. This will probably make it much bigger and heavier than a "standard" flange of the same rating which is probably why no one does this for any flange with a decent pressure rating when quick opening closures are much better. It is also common knowledge that flanges to B 16.5 fail when designed to ASME VIII, but are permitted under the rules as being certified to B 16.5. However any flanges outside the range need to be specifically designed to ASME VIII and hence tend to be bigger and heavier.

I can't see much advantage myself to this arrangement as you still need to undo each nut in turn and then do them all up again. The minor time saving in not having to unscrew the nuts another three or four turns does not seem worth it to me... your term "instantly open all bolts" is, unfortunately, simply not possible.

My motto: Learn something new every day

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

 

[SnTMan]

The advantage is that such an arrangement is not considered by Sec VIII, Div 1 as a "quick opening closure" and therfore does not fall under UG-35.2. See UG-35.2(a)(1). This arrangement is widely used.

Regards,

Mike

 

[SyedZainAli]

thanks alot guys