Variable section opening

[nachocivicos]

Hi,

I have to design a variable section opening in a flat head; it begins with 32 mm diameter inwards, follows with a conical enlargement and ends with a BSP female thread 1 1/2", but I have not found any reference in ASME Sec. VIII Div. 1 to variable section openings. Any other similar experience/reasonable interpretation? How should I check the need for reinforcement?

Thanks in advance,

J.I.G.C.
Chemical Engineer

 

[doct9960]

nachocivicos,

If the opening is not subject to rapid fluctuations in pressure and the finished opening in the flat head is not more than 60 mm, reinforcement is not required. See UG-36(c)(3).

 

[nachocivicos]

doct9960,

Thank you for your fast reply, and sorry for the missing information above, where I did not tell I have multiple openings. My problem arises not from size requirements, but from spacing requirements in UG-36 (c) (3)(d), where the mentioned opening with say d1 = 1 1/2" is nearer than 2.5 (d1 + d2) from the other closer opening in a cluster of three openings. Hence, I suppose UG-39 should apply anyway and eventually the question for which diameter to use in reinforcement calculations remains.

Could you or anyone else be so kind to give me some light on this?

 

[prex]

If you use the largest diameter (bottom of threads I suppose), then you won't have to discuss with the AI afterwards. Otherwise you could adapt the method for multidiameter holes in App.13 (if I recall correctly), but you'll need to justify your position in detail.

prex

http://www.xcalcs.com

: Online engineering calculations

http://www.megamag.it

: Magnetic brakes for fun rides

http://www.levitans.com

: Air bearing pads

 

[doct9960]

Even if reinforcement requirements are met, the AI needs to be involved because of the BSP thread. UG-43(e) only covers threaded connections that conform to ASME B1.20.1. For other thread standards like BSP, see U-2(g).