Hole in a Blind B16.5
Hole in a Blind B16.5
(OP)
Hi all,
I've this std blind 5 NPS acc. to B16.5. Now I want to drill a 2 NPS hole not in the center of the flange so that after I could weld a 2" LWN std acc. to ASME B 16.5. First of all, do I have to check the calcs? Is it permitted to drill a hole of this dimension? I check in B16.5 - Table 6, but I don't understand the point: do I need to reinforce the LWN? Would it be different if the hole is centered? Help! Thanks.
I've this std blind 5 NPS acc. to B16.5. Now I want to drill a 2 NPS hole not in the center of the flange so that after I could weld a 2" LWN std acc. to ASME B 16.5. First of all, do I have to check the calcs? Is it permitted to drill a hole of this dimension? I check in B16.5 - Table 6, but I don't understand the point: do I need to reinforce the LWN? Would it be different if the hole is centered? Help! Thanks.





RE: Hole in a Blind B16.5
Actually, with that tight a group of mis-matched, off-centered, non-Code-standard drilled and welded fittings all crammed into a short pressure fitting, you really DO need an accurate full 3D finite element analysis. Done by somebody who knows FEA and its limits.
What is your operating pressure, what temperature, and what fluid?
What materials do you think you are going to use?
How will you weld them, and with what filler?
RE: Hole in a Blind B16.5
Under ASME VIII Div.1 this would require a reinforcement check per UG-39, as the opening exceeds one fourth the head diameter.
prex
http://www.xcalcs.com : Online engineering calculations
http://www.megamag.it : Magnetic brakes and launchers for fun rides
http://www.levitans.com : Air bearing pads
RE: Hole in a Blind B16.5
yes prex, the LWN has to be welded on the same hole, but I would ask: is there a size for the hole under that you might not check the calc's? A size that you can say "Ok, there's a hole, but the blind is according to B16.5, so it's ok"? Thank you all!
RE: Hole in a Blind B16.5
Another example; if you'd have a 4" blind, you would not need to do calcs for 1" holes and smaller. Ona 4" blind with a 1.1/2" hole, you however would need to do the calcs.
Slightly off topic, but B16.5 table 6 is often looked at as being related to holes in the centre. Off-centre holes are not allowed. You may want to review this informative thread too. There seems to be nothing in B16.5 explicitly saying this though.
RE: Hole in a Blind B16.5
5 inch NPS "pipe" of some unknown schedule made of some unknown material withstanding an unknown pressure at an unknown temperature of an unknown liquid (gas maybe?) of unknown properties. This "pipe" is mounted (somehow) to a 5 inch NPS flange (of some unknown class and material) that will be covered by a 5 inch blind flange (of unknown material and class), but it will be drilled out with a hole (maybe on-center or off-center) to weld on a 2 inch NPS Long Weld Neck flange.
The 2 inch NPS LWN is 2.375 OD, so your hole must be at least 2.4375 diameter for the new pipe to slide into to permit a outside fillet weld. That 2.4375 hole is more than half of the ID of the original 5 inch "pipe" that you are connecting the blind flange to. The fillet welds around the OD of the 2.375 will be at least 1/4 radius, thus the OD of the weld - without considering access margin outside of the wled - is 2.375 + .5 or 2.875 diameter across that original 5 inch blank flange.
And you ask if you need to analyze this?
Use a Code-rated reducer and full penetration butt welds. If you need to drain the 5 inch "pipe" use a Code-rated eccentric reducer,, flat side down. IF this entire jury-rig must be bolted-on, bolted-off assembly, put a 5 inch flange upstream of the reducer, and a 2 inch flange downstream of the reducer.
RE: Hole in a Blind B16.5
UG-36 (c) allows openings max 60mm in flat heads with required min thickness over 10 mm (this is my case). Under this condition I can consider the blind flange as a flat head which is according to B16.5 and drill a hole <=2". Is it ok? thanks
P.S: racookpe1978 lol! yeah, I'm the "Unknown" man :)
RE: Hole in a Blind B16.5
RE: Hole in a Blind B16.5
As you are asking advice here, why don't you listen to the advice you receive?
prex
http://www.xcalcs.com : Online engineering calculations
http://www.megamag.it : Magnetic brakes and launchers for fun rides
http://www.levitans.com : Air bearing pads
RE: Hole in a Blind B16.5
In your case, you are exceeding the values provided in Table 6, so you must do calculations to determine the pressure/temperature rating of the blind flange.
Cheers,
Marty
RE: Hole in a Blind B16.5
RE: Hole in a Blind B16.5