Hub definition

[geodesia]

Hi all,
I was having a look to the Code, trying to solve aproblem with a butt weld, and I have been searching for the definiton of hub...and didnt find anything in ASME VIII Div.1!
Can anybody tell me if ASME Codedefines "hub" or give minimum dimension/requirements so that a "hub" is a "hub"?

 

[MrBTU]

See fig 2-4

 

[geodesia]

Thanks MRBTU!!...but the hubs shown are only for flange, and I would eed something more generic, and in particular, when it is referred to a butt weld joint (not only for flange connections)

 

[MrBTU]

In the case of a butt weld joint, between two pipes or two cylinders, the bevelled portion of the pipe is called a groove, for a full penetration groove weld, and is defined by UW-9(b). Can you give us more details as to what you are welding to what?

 

[geodesia]

I am weldin a flatside with another one using a hub, following te figure of ASME VIII Div.1 Code UW-13.3, but my discussion has derived to what a hub is

 

[unclesyd]

In general any integral projection on/from the backside of a flange ring.

 

[geodesia]

Thanks unclesyd
But I would like an "offitial" definition, a I had a similar idea of what a hub is to yours, a projection from a surface (noy only flange) in order to use it as attachment to be weld, but I dont find it in the code, so that I can apply to detail in fig. UW-13.3 and stablish minimum distance to bevel edge

 

[unclesyd]

Drill down under the technical section and checkout weld end prep.

It is hard to pin down your exact question as a lot of fittings have a hub and are not made to weld to, like a blind flange, DI pipe, and Lap joint.

http://www.forgedcomponents.com/

 

[geodesia]

I know unclesyd,
But what I need it is a clear defintion (preferably given by the code) so that you can say that hsi is a hub or this is not.

 

[LSThill]

geodesia (Petroleum)

Did you search for ASME SECTION VIII, DIVISION 1, INTERPRETATION clear defintion hub, or have you written to ASME SECTION VIII, DIVISION 1, FOR INTERPERATION clear defintion hub

Regards



L S THILL

 

[geodesia]

HI LST hill,
My next step will be to ask the question to the Code, but I am involved right now in a discussion that I need to solve.
So it will be useful for the future, not now.

I didnt find any interpretation for defintion of hub, only found this one:

Interpretation: V111-1-01-18
Subject: Section VIII, Division 1 (1 998 Edition, 1999
Addenda); Fig. UW-13.3 Sketch (b)
Date Issued: January 3, 2001
File Number: BC00-688
Related
Documents:
Question: For the configuration shown in Fig. UW-13.3 sketch (b) of Section VIII, Division 1, the extent of projection of the hub beyond the face of the flat head or tubesheet is not specified. Do the requirements provide for minimum and maximum projection of the hub?
Reply: No.

But this doesnt clarify my doubt, as for example, in my company we have two differentt interpreation of what the hub is, and if the projection beyond the face of the flat head can be "negative" , as it doesnt specify a minimum.

 

[unclesyd]

This paper doesn't completely answer your question though it does throw a little light on the intent and purpose of a hub.
Paraphrasing from the paper;
A simplistic definition would be is that a hub is a projection to move a weld out of the plane of the maximum bending stress at a vessel discontinuity with the added benefit of better inspection.

http://www.beasy.com/images/pdf/publications/pressurevessel.pdf

 

[geodesia]

Thats exactly what I would need! But it should be an "offitial definition" so that it can be considered as "contractual" if the code is applied.
So,if somebody finds something similar to this...

Thanks a lot unclesyd