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Hub on lapped flange
16 years 2 months ago - 16 years 2 months ago #7282 by gpsvn
Hub on lapped flange was created by gpsvn
I am being asked a question, and I don't know the answer. I am posting it here and appreciate responses from the forum members.
The lapped flanges are used in companion with the stub ends. My engineer received a batch of flanges without their 'hubs'. His question is, why the lapped flanges need hubs, what are their purposes. I can only say those flanges must meet ASME B16.5, which dictates the flange and hub dimensions. I guess my answer was not a real answer, did not help him much. Any one help me out please.
The lapped flanges are used in companion with the stub ends. My engineer received a batch of flanges without their 'hubs'. His question is, why the lapped flanges need hubs, what are their purposes. I can only say those flanges must meet ASME B16.5, which dictates the flange and hub dimensions. I guess my answer was not a real answer, did not help him much. Any one help me out please.
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16 years 2 months ago - 16 years 2 months ago #4496 by gpsvn
I asked the engineer to return those flanges, that's why he asked me those questions. There is no welding on the hub, so why do we need it ?
A lap joint and a flat face slip on are different. Look at the corner between the flange ID and the face, the slip on has a sharp angle while the lapped flange has a rounded one. If you look close enough, the lapped flange is thicker.
It's not the stub end, it's the HUB. The hub is where you weld to the pipe on the back side of a slip on flange. The lapped flange according to ASME B16.5 also has hub, that's what being discussed.
Replied by gpsvn on topic Re: Flanges
gpsvn,
I have never seen hubless Lap-joint-flanges. I would suggest that someone trace these flanges back to the source and confirm that they are not counterfeiters.
Read the related article under "I saw a good article"
I asked the engineer to return those flanges, that's why he asked me those questions. There is no welding on the hub, so why do we need it ?
Hello, Well let me ask you this, what is the difference between a Slip-on flange and a Lap-joint (without the stub end of course). If you can go out to your warehouse and check them out.
For one there is no RF...
A lap joint and a flat face slip on are different. Look at the corner between the flange ID and the face, the slip on has a sharp angle while the lapped flange has a rounded one. If you look close enough, the lapped flange is thicker.
Well I guess there is absolutley no meaning of existence for a LAp-joint flange without its stub end, tell your boss to weld them and make a statue or something... sorry for the irony
REgards
It's not the stub end, it's the HUB. The hub is where you weld to the pipe on the back side of a slip on flange. The lapped flange according to ASME B16.5 also has hub, that's what being discussed.
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16 years 2 months ago - 16 years 2 months ago #4498 by gpsvn
I guess I did not express myself too well.
Replied by gpsvn on topic " There is no welding
" There is no welding on the hub, so why do we need it ? "
The hub provides stability and resistance to flexing or twisting of the flange. Consider the situation where you have a 6"NPS flange shape with no hub that is very thin, only about 1/8" (3.175 mm) thick. With your bare hands you will be able to twist the plate with ease. Now take one with a raised hub. You will find that the one with the raised hub will be resistant to the twisting effect.
So the hub helps to maintain the constant and consistent pressure against the lip of the "Stub End" piece to insure a proper joint.
I guess I did not express myself too well.
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